# Factors associated with dietary practices and beliefs on food of patients with rheumatic and musculoskeletal diseases: A multicentre cross-sectional study

Domitille Renard, Sophie Tuffet, Philippe Dieudé, Pascal Claudepierre, Laure Gossec, Bruno Fautrel G H I, Anna Molto, Corinne Miceli-Richard, Pascal Richette, Emmanuel Maheu, et al.

<figure><img src="image_1.png" /></figure>

## To cite this version:

Domitille Renard, Sophie Tuffet, Philippe Dieudé, Pascal Claudepierre, Laure Gossec, et al. Factors associated with dietary practices and beliefs on food of patients with rheumatic and musculoskeletal diseases: A multicentre cross-sectional study. Joint Bone Spine, 2025, 92 (1), pp.105778. 10.1016/j.jbspin.2024.105778. hal-04969430

HAL Id: hal-04969430

https://hal.science/hal-04969430v1

Submitted on 27 Feb 2025

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

<figure><img src="image_2.png" /></figure>
# Factors associated with dietary practices and beliefs on food of patients with rheumatic and musculoskeletal diseases: A multicentre cross-sectional study

## Author

Domitille Renard<sup>a</sup>, Sophie Tuffet<sup>b</sup>, Philippe Dieudé<sup>c</sup>, Pascal Claudepierre<sup>d</sup>, Laure Gossec<sup>e f</sup>, Bruno Fautrel<sup>g h i</sup>, Anna Molto<sup>j k</sup>, Corinne Miceli- Richard<sup>l</sup>, Pascal Richette<sup>m</sup>, Emmanuel Maheu<sup>a</sup>, Claire Carette<sup>n</sup>, Sébastien Czernichow<sup>n</sup>, Chloé Jam akorzyan<sup>o</sup>, Alexandra Rousseau<sup>b</sup>, Francis Berenbaum<sup>p</sup>, Catherine Beauvais<sup>q r</sup>, Jérémie Sellam<sup>r s t</sup>

Department of Rheumatology, Saint-Antoine Hospital, Assistance publique-Hôpitaux de Paris (AP-HP), 184, rue du Faubourg Saint-Antoine, 75012 Paris, France

Department of Clinical Pharmacology-Clinical Research Platform Paris-East (URCEST-CRC-CRB), Hôpital Saint-Antoine, Sorbonne University (AP-HP), 184, rue du Faubourg Saint-Antoine, 75012 Paris, France

Inserm UMR1152, Department of Rheumatology, DMU Locomotion, Hôpital Bichat - Claude-Bernard (AP-HP), Université de Paris, 46, rue Henri-Huchard, 75018 Paris, France

Department of Rheumatology, Henri-Mondor University Hospital (AP-HP), 1, rue Gustave-Eiffel, 94010 Créteil, France

Inserm, institut Pierre-Louis d'épidémiologie et de santé publique, Sorbonne université, 56, boulevard Vincent-Auriol, 75013 Paris, France

Department of Rheumatology, Pitié-Salpêtrière Hospital (AP-HP), 47-83, boulevard de l'Hôpital, 75013 Paris, France

Department of Rheumatology, Pitié-Salpêtrière Hospital, Sorbonne Université (AP-HP), 47-83, boulevard de l'Hôpital, 75013 Paris, France

CRI-IMIDIATE Clinical Research Network, Paris, France

Inserm UMR 1136, Pierre-Louis Institute of Epidemiology and Public Health, 56, boulevard Vincent-Auriol, 75013 Paris, France

Department of Rheumatology, Hôpital Cochin (AP-HP), Paris Centre University, 27, rue du Faubourg Saint-Jacques, 75014 Paris, France

Inserm U-1153 ECAMO Team, CRESS, Paris-Cité University, 27, rue du Faubourg Saint-Jacques, 75014 Paris, France

Department of Rheumatology, Paris Centre University, Hôpital Cochin (AP-HP), 27, rue du Faubourg Saint-Jacques, 75014 Paris, France

Department of Rheumatology, Lariboisière Hospital (AP-HP), 2, rue Ambroise-Paré, 75010 Paris, France

Department of Nutrition, Specialized Obesity Center, Hôpital européen Georges-Pompidou (AP-HP), Université de Paris, 20, rue Leblanc, 75015 Paris, France

Department of Rheumatology, Hôpital d'instruction des Armées Bégin, 69, avenue de Paris, 94160 Saint-Mandé cedex, France

Inserm UMRS_938, Department of Rheumatology, Centre de Recherche Saint-Antoine, Paris Center for Microbiome Medicine (PaCeMM) FHU, Saint-Antoine Hospital (AP-HP), Sorbonne Université, 184 rue du Faubourg Saint-Antoine, 75012 Paris, France

Department of Rheumatology, Saint-Antoine Hospital, Sorbonne University (AP-HP), 184, rue du Faubourg Saint-Antoine, 75012 Paris, France
## Highlights

<figure><img src="image_3.png" /></figure>

Exclusion diets are not advocated in rheumatic diseases but are followed by some patients to alleviate their symptoms.

<figure><img src="image_4.png" /></figure>

Knowledge is lacking on the factors associated with adherence to these diets.

<figure><img src="image_5.png" /></figure>

In this study, 26% patients had tried an exclusion diet and 42% found a benefit of at least one dietary component.

<figure><img src="image_6.png" /></figure>

Factors associated with dieting and its perceived impact on pain were patients' health beliefs, the use of complementary medicine, and lack of support or information.

## Abstract

### Objectives

To investigate dietary practices and beliefs of patients with rheumatic and musculoskeletal diseases (RMDs) and associated factors.

### Methods

In 2019–2020, a cross-sectional multicentre study enrolled patients with inflammatory arthritis (IA) (rheumatoid arthritis [RA], axial spondyloarthritis [axSpA]) or hand osteoarthritis (HOA) from secondary- and tertiary-care centres. A self-administered questionnaire explored dietary practices and patients’ perceived effects of diet, foods and beverages on symptoms. Univariable and multivariable analyses investigated factors associated with diets and patients’ views.

### Results

Of 448 included patients, data for 392 were analysed (123 with RA, 161 with axSpA, 108 with HOA), 26% were on or had been on at least one exclusion diet (mostly cow's milk- and gluten-free diets in IA, mostly cow's milk-free diet and detox/fasting in HOA). Only 5% of patients followed the Mediterranean diet. Among patients who had tried a diet, 51% reported a decrease in pain. Overall, 42% of patients identified at least one food or beverage that increased or decreased pain. On multivariable analyses, dieting or the perceived effect of food on pain was associated with health beliefs (positive or negative), the use of complementary and alternative medicines, and lack of support or information from healthcare professionals. Patients had received little dietary information from their physicians.

### Conclusions

This study provides insights into patients’ dietary practices and factors associated with these practices, including patients’ health beliefs and insufficient support by health professionals, in RMDs.
# 1. Introduction

Inflammatory arthritis (IA) and osteoarthritis (OA) are the most common rheumatic and musculoskeletal diseases (RMDs). They cause chronic pain, joint damage and impaired quality of life. Recommendations for disease management include pharmacological and non-pharmacological treatments [1], [2], [3]. Nutritional advice has been scarce or non-existent until the publication of the recommendations of the European Alliance of Associations for Rheumatology (EULAR) regarding lifestyle behaviours for patients with IA and OA [4] and the dietary recommendations of the French Society of Rheumatology (SFR) for patients with IA [5].

Diet has long been a subject of questioning and beliefs among patients with RMDs [6], [7]. Some patients seek to improve their quality of life and alleviate their symptoms by changing their dietary habits [8], such as following a gluten-free diet [9]. These behaviours can be facilitated by dietary trends in the general population, such as the increasing frequency of exclusion diets or the consumption of organic food [10] and also by the multiple sources of information easily accessible to patients such as on the Internet and social media.

There is some evidence that diet plays a role in the onset of IA [11] and increasing research on gut microbiota in RMDs [12]. Although dietary intervention trials are often inconclusive [4], [5], [13], patients can be exposed to non-scientific information and “fake news” [14]. The response of healthcare professionals (HPs) to patients’ need for advice seem insufficient [9] and could be helped by a better knowledge of patients’ dietary practices. A recent study of patients with IA showed that 30% to 40% had changed their nutritional habits [9], but knowledge is still lacking on the type of diets and factors related to following such diets.

In this context, we aimed to explore patients' dietary practices, their perception of the effects of diets and food on their rheumatic symptoms, and factors associated with following these diets.

# 2. Methods

## 2.1. Study design and participants

RHUMADIET (Rheumatism and Dietetic: food practices and beliefs; ClinicalTrials.gov NCT03770884) was a multicentre cross-sectional study of patients attending 6 rheumatology departments of university hospitals in the Paris region (France) during hospitalization or in outpatient clinics. Patients were enrolled on a voluntary basis by the rheumatologists between January 2019 and May 2020. The inclusion criteria were age > 18 years, a diagnosis of rheumatoid arthritis (RA; fulfilling the American College of Rheumatology/EULAR [ACR/EULAR] criteria [15]), a diagnosis of axial spondyloarthritis (axSpA; fulfilling the 2009 Assessment of SpondyloArthritis International Society Classification criteria [16]) or a diagnosis of hand OA (HOA; fulfilling the 1990 ACR criteria [17]). Patients unable to complete a questionnaire in French were not eligible. Patients with peripheral SpA or with HOA with a predominant symptomatic knee or hip were also excluded in order to obtain rather homogeneous samples of each rheumatic disease phenotype. HOA was also preferred over knee OA because it is less weight-related as compared with weight-bearing joints such as the knee, and patients were less likely to change their eating habits in order to lose weight.

## 2.2. Ethics

All participants gave their informed consent for the study. The research was approved by the French ethics committee (Comité de protection des personnes, Île-de-France VI; ID RCB 2018 A01340-55).

## 2.3. Outcome measures and collected data

Outcomes and data were collected by a paper questionnaire completed by patients and rheumatologists.

### 2.3.1. Outcomes

The primary outcome was the proportion of patients who were following or had followed one or more diets of whatever duration over their lifetime in the total sample and for each RMD.
Secondary outcomes were: (1) the type of diet followed for each RMD; (2) patients' opinions about the positive or negative effect of dieting on pain, fatigue or general condition as well as the effect of particular foods and/or beverages on pain; (3) factors associated with dieting; and (4) factors associated with patients' views on the effect of food or drinks on pain.

### 2.3.2. Dietary assessment

In the absence of a validated questionnaire, the steering committee developed a questionnaire taking into account existing data on food patterns in RMDs or in the general population [8], [9], [10]. Patients were asked if they were following or had followed one or more diets (and for how long) among the following diets: Mediterranean, lactose-free, cow's milk-free, gluten-free, vegetarian (no meat, fish or poultry), vegan (plant-based), detox/fasting (low glycemic and energy intake, interspersed with periods of normal eating) [18], and the so-called Seignalet diet popular in France for over 30 years, which is close to "hypotoxic and ancestral" diets [19]. Because of the length of the questionnaire, diets were not detailed in the survey. Investigators simply answered the patients' questions while they completed the questionnaire. For past or present diet practice, patients were asked about their source of information (Who advised you about this type of diet? How did you hear about it?) with a list of possible answers: physician, dietician, other HPs, other patients, relatives, the Internet and social media, conventional media, brochures and books.

We collected patients' opinions of the effect (improvement, worsening, or no effect) of diet on pain, fatigue and general condition. Then patients were invited to answer the question "In your opinion, does your dietary intake change (for good or bad) your rheumatic symptoms?" (yes, no, I do not know) and to name from a list of 50 foods, beverages, food categories, or dietary supplements (list in supplementary material 1), those that had an effect on pain intensity (improvement, worsening, no effect, I do not know).

### 2.3.3. Sociodemographic and clinical variables

The collected data (Table 1) were sociodemographics, type of disease and disease characteristics, type of follow-up, treatments including the current or past use of complementary and alternative medicine (CAM), comorbidities [20], adherence to medication, body mass index (BMI), current or past tobacco consumption, current alcohol consumption, and conditions that may affect dietary practices such as inflammatory bowel disease (IBD), irritable bowel syndrome, celiac disease, non-celiac gluten sensitivity, gastrointestinal reflux disease, lactose intolerance, and salt-free or diabetic diets. The Rheumatoid Arthritis Impact of Disease (RAID) was used to evaluate the impact of disease and the Fibromyalgia Rapid Screening Tool (FIRST) to detect the presence of criteria for fibromyalgia [21], [22]. Disease activity was collected with the Bath Ankylosing Spondylitis Activity Index (BASDAI) (Table 1), Ankylosing Spondylitis Disease Activity Score (ASDAS) for axSpA and Disease Activity Score in 28 joints-C-reactive protein (DAS28-CRP) for RA. Functional impairment of HOA patients was assessed with the gender-neutral Functional Index for HOA (FIHOA) [23]. Patients self-assessed their level of information with the question "In your opinion, what is your level of information about your disease/your treatments?" (0, not at all informed, to 10, very well informed) [24]. Patients self-assessed their support by their level of agreement to the statement "In general, I feel well supported regarding my condition by my doctor/the people close to me." (not at all/fairly little/quite often/often) [25].
<table><caption>Table 1. Demographics, co-morbidities, disease characteristics, impact of disease, adherence to treatment, support and information, lifestyle habits, and health beliefs of patients with rheumatic and musculoskeletal diseases.</caption><thead><tr><th rowspan="2"></th><th colspan="2">AxSpA (n = 161)</th><th colspan="2">RA (n = 123)</th><th colspan="2">HOA (n = 108)</th></tr><tr><th>No.<sup>a</sup></th><th>Empty Cell</th><th>No.<sup>a</sup></th><th>Empty Cell</th><th>No.<sup>a</sup></th><th>Empty Cell</th></tr></thead><tbody><tr><td>Female, no. (%)</td><td>161</td><td>67 (41.6)</td><td>123</td><td>104 (84.6)</td><td>108</td><td>91 (84.3)</td></tr><tr><td>Age, years, mean ± SD</td><td>159</td><td>46.2 ± 12.3</td><td>123</td><td>56.2 ± 12.2</td><td>108</td><td>69.2 ± 7.0</td></tr><tr><td>Follow-up in hospital, no. (%)</td><td>161</td><td>130 (80.7)</td><td>123</td><td>109 (88.6)</td><td>107</td><td>56 (52.3)</td></tr><tr><td>Professional activity, no. (%)</td><td>151</td><td></td><td>118</td><td></td><td>101</td><td></td></tr><tr><td>Currently employed</td><td></td><td>103 (68.2)</td><td></td><td>53 (44.9)</td><td></td><td>12 (11.9)</td></tr><tr><td>Retired</td><td></td><td>18 (11.9)</td><td></td><td>41 (34.7)</td><td></td><td>87 (86.1)</td></tr><tr><td>On sick leave/disability</td><td></td><td>30 (19.9)</td><td></td><td>24 (20.3)</td><td></td><td>2 (2.0)</td></tr><tr><td>High level of education, no. (%)</td><td>151</td><td>94 (62.3)</td><td>121</td><td>49 (40.5)</td><td>101</td><td>59 (58.4)</td></tr><tr><td>Socio-professional status (SPS), no. (%)</td><td>150</td><td></td><td>121</td><td></td><td>100</td><td></td></tr><tr><td>High SPS</td><td></td><td>56 (37.3)</td><td></td><td>29 (24.0)</td><td></td><td>43 (43.0)</td></tr><tr><td>Low SPS</td><td></td><td>94 (62.7)</td><td></td><td>92 (76.0)</td><td></td><td>57 (57.0)</td></tr><tr><td>BMI, kg/m<sup>2</sup>, mean ± SD</td><td>149</td><td>25.3 ± 5.2</td><td>121</td><td>25.7 ± 4.9</td><td>108</td><td>23.8 ± 3.5</td></tr><tr><td>Obesity (BMI ≥ 30 kg/m<sup>2</sup>), no. (%)</td><td>149</td><td>20 (13.4)</td><td>121</td><td>22 (18.2)</td><td>108</td><td>6 (5.6)</td></tr><tr><td>Comorbidities (Groll Index) (0–18), median (IQR)</td><td>148</td><td>1.0 (0.0–2.0)</td><td>119</td><td>1.0 (0.0–3.0)</td><td>106</td><td>2.0 (1.0–3.0)</td></tr><tr><td>Gastrointestinal disease, no. (%)</td><td>161</td><td>40 (24.8)</td><td>122</td><td>9 (7.4)</td><td>107</td><td>22 (20.6)</td></tr><tr><td>IBD (Crohn's disease/ulcerative colitis)</td><td>161</td><td>27 (16.8)</td><td>123</td><td>1 (0.8)</td><td>107</td><td>1 (0.9)</td></tr><tr><td>Gastrointestinal reflux disease</td><td>161</td><td>7 (4.3)</td><td>123</td><td>8 (6.5)</td><td>107</td><td>21 (19.6)</td></tr><tr><td>Irritable bowel syndrome</td><td>161</td><td>7 (4.3)</td><td>123</td><td>2 (1.6)</td><td>107</td><td>6 (5.6)</td></tr><tr><td>Non-celiac gluten sensitivity</td><td>161</td><td>4 (2.5)</td><td>123</td><td>0 (0)</td><td>107</td><td>0 (0)</td></tr><tr><td>Lactose intolerance</td><td>161</td><td>4 (2.5)</td><td>122</td><td>1 (0.8)</td><td>107</td><td>1 (0.9)</td></tr><tr><td>Salt-free diet, no. (%)</td><td>160</td><td>1 (0.6)</td><td>123</td><td>8 (6.5)</td><td>107</td><td>2 (1.9)</td></tr><tr><td>Diabetic diet, no. (%)</td><td>160</td><td>2 (1.3)</td><td>123</td><td>11 (8.9)</td><td>107</td><td>0 (0)</td></tr><tr><td>RMD duration, years, median (IQR)</td><td>155</td><td>12.0 (6.0–19.0)</td><td>120</td><td>13.0 (7.0–23.5)</td><td>92</td><td>10 (8.0–20.0)</td></tr><tr><td>axSpA features, no. (%)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Axial involvement</td><td>160</td><td>158 (98.8)</td><td></td><td></td><td></td><td></td></tr><tr><td>Peripheral/enthesitis</td><td>160</td><td>109 (68.1)</td><td></td><td></td><td></td><td></td></tr><tr><td>HOA features, no. (%)</td><td></td><td></td><td></td><td></td><td>108</td><td></td></tr><tr><td>HOA only</td><td></td><td></td><td></td><td></td><td></td><td>35 (32.4)</td></tr><tr><td>HOA plus other sites</td><td></td><td></td><td></td><td></td><td></td><td>73 (67.6)</td></tr><tr><td>Active disease, no. (%)</td><td>155</td><td>112 (72.3)</td><td>117</td><td>22 (18.8)</td><td>105</td><td></td></tr><tr><td>ASDAS ≥ 1.3<sup>b</sup></td><td>139</td><td>105 (75.5)</td><td></td><td></td><td></td><td></td></tr></tbody></table>
<table><thead><tr><th></th><th>AxSpA (n = 161)</th><th>RA (n = 123)</th><th>HOA (n = 108)</th></tr><tr><th></th><th>No.<sup>a</sup></th><th>No.<sup>a</sup></th><th>No.<sup>a</sup></th></tr></thead><tbody><tr><td>BASDAI ≥ 4/10<sup>b</sup></td><td>155</td><td>77 (49.7)</td><td></td></tr><tr><td>DAS28-CRP ≥ 3.2<sup>b</sup></td><td></td><td>117</td><td>22 (18.8)</td></tr><tr><td>FIHOA ≥ 5/30<sup>b</sup></td><td></td><td></td><td>105</td><td>59 (56.2)</td></tr><tr><td>Number of treatments (past or current),<br>mean ± SD (range)</td><td>142</td><td>1.8 ± 1.6<br>(0.0–8.0)</td><td>3.5 ± 2.0 (0.0–<br>10.0)</td><td></td></tr><tr><td>Current treatments, no. (%)</td><td></td><td></td><td></td><td></td></tr><tr><td>RA and axSpA</td><td></td><td></td><td></td><td></td></tr><tr><td>NSAIDs</td><td>161</td><td>76 (47.2)</td><td>123</td><td>17 (13.8)</td></tr><tr><td>Corticosteroids</td><td>161</td><td>7 (4.3)</td><td>123</td><td>49 (39.8)</td></tr><tr><td>cDMARDs</td><td>159</td><td>30 (18.9)</td><td>123</td><td>100 (81.3)</td></tr><tr><td>bDMARDs (SC or IV)</td><td>156</td><td>113 (72.4)</td><td>120</td><td>99 (82.5)</td></tr><tr><td>JAKi</td><td>156</td><td>0 (0)</td><td>120</td><td>5 (4.2)</td></tr><tr><td>HOA</td><td></td><td></td><td></td><td></td></tr><tr><td>NSAIDs</td><td></td><td></td><td>108</td><td>49 (45.4)</td></tr><tr><td>Analgesics</td><td></td><td></td><td>108</td><td>48 (44.4)</td></tr><tr><td>Symptomatic slow-acting drugs</td><td></td><td></td><td>108</td><td>19 (17.6)</td></tr><tr><td>Total RAID score<sup>b</sup> (0–10), median (IQR)</td><td>159</td><td>4.7 (1.9–6.7)</td><td>121</td><td>3.7 (1.8–5.5)</td><td>105</td><td>3.2 (1.9–<br>5.0)</td></tr><tr><td>FIRST score (0–6), median (IQR)</td><td>145</td><td>3.0 (2.0–5.0)</td><td>111</td><td>2.0 (0.0–4.0)</td><td>94</td><td>1.0 (0.0–<br>3.0)</td></tr><tr><td>FIRST score ≥ 5/6, no. (%)</td><td>153</td><td>42 (27.5)</td><td>116</td><td>17 (14.7)</td><td>100</td><td>10 (10.0)</td></tr><tr><td>Adherence to cDMARDS (RA and axSpA)</td><td>20</td><td></td><td>86</td><td></td><td></td><td></td></tr><tr><td>Good</td><td></td><td>11 (55.0)</td><td></td><td>51 (59.3)</td><td></td><td></td></tr><tr><td>Adherence to bDMARDS (RA and<br>axSpA)</td><td>41</td><td></td><td>18</td><td></td><td></td><td></td></tr><tr><td>Good</td><td></td><td>26 (63.4)</td><td></td><td>15 (83.3)</td><td></td><td></td></tr><tr><td>Support from relatives (often or quite<br>often), no. (%)</td><td>160</td><td>127 (79.4)</td><td>123</td><td>96 (78.0)</td><td>106</td><td>69 (65.1)</td></tr><tr><td>Support from physician (often or quite<br>often), no. (%)</td><td>160</td><td>145 (90.6)</td><td>123</td><td>109 (88.6)</td><td>103</td><td>59 (57.3)</td></tr><tr><td>Information about disease (0–10)<sup>c</sup>,<br>median (IQR)</td><td>161</td><td>8.0 (7.0–9.0)</td><td>122</td><td>8.0 (7.0–9.0)</td><td>108</td><td>6.0 (4.0–<br>8.0)</td></tr><tr><td>Information about treatments (0–10)<sup>c</sup>,<br>median (IQR)</td><td>160</td><td>8.0 (6.0–9.0)</td><td>122</td><td>8.0 (7.0–9.0)</td><td>97</td><td>6.0 (3.0–<br>8.0)</td></tr><tr><td>Current alcohol consumption (daily or<br>occasional), no. (%), yes</td><td>159</td><td>100 (62.9)</td><td>121</td><td>69 (57.0)</td><td>107</td><td>86 (80.4)</td></tr><tr><td>Number of drinks/week, median (IQR)</td><td>92</td><td>4.0 (2.0–6.5)</td><td>64</td><td>2.0 (1.0–4.0)</td><td>85</td><td>4.0 (2.0–<br>7.0)</td></tr></tbody></table>
<table><thead><tr><th rowspan="2"></th><th colspan="2">AxSpA (n = 161)</th><th colspan="2">RA (n = 123)</th><th colspan="2">HOA (n = 108)</th></tr><tr><th>No.<sup>a</sup></th><th>Empty Cell</th><th>No.<sup>a</sup></th><th>Empty Cell</th><th>No.<sup>a</sup></th><th>Empty Cell</th></tr></thead><tbody><tr><td>Tobacco consumption (current or past), no. (%), yes</td><td>161</td><td>78 (48.4)</td><td>122</td><td>47 (38.5)</td><td>107</td><td>32 (29.9)</td></tr><tr><td>Number of cigarette packs year, median (IQR)</td><td>54</td><td>20.0 (14.0–25.0)</td><td>29</td><td>30.0 (14.0–40.0)</td><td>22</td><td>24.5 (15.0–35.0)</td></tr><tr><td>Use of CAM, no. (%) (at least one)</td><td>161</td><td>46 (28.6)</td><td>122</td><td>38 (31.1)</td><td>107</td><td>37 (34.6)</td></tr><tr><td>Homeopathy</td><td>161</td><td>22 (13.7)</td><td>122</td><td>21 (17.2)</td><td>107</td><td>19 (17.8)</td></tr><tr><td>Phytotherapy</td><td>161</td><td>11 (6.8)</td><td>122</td><td>5 (4.1)</td><td>107</td><td>12 (11.2)</td></tr><tr><td>Acupuncture</td><td>161</td><td>22 (13.7)</td><td>122</td><td>11 (9.0)</td><td>107</td><td>18 (16.8)</td></tr><tr><td>Relaxation-sophrology</td><td>161</td><td>24 (14.9)</td><td>122</td><td>22 (18.0)</td><td>107</td><td>8 (7.5)</td></tr><tr><td>Positive beliefs (physical activity is beneficial) (0–10)<sup>c</sup>, median (IQR)</td><td>159</td><td>9.0 (7.0–10.0)</td><td>120</td><td>8.5 (7.0–10.0)</td><td>107</td><td>9.0 (8.0–10.0)</td></tr><tr><td>Negative beliefs (0–10)<sup>b</sup>, median (IQR)</td><td>154</td><td>4.3 (3.0–5.7)</td><td>116</td><td>4.8 (2.7–5.8)</td><td>103</td><td>3.7 (2.0–5.7)</td></tr><tr><td>Doubts about vaccines (0–10)<sup>b</sup></td><td>157</td><td>5.0 (1.0–6.0)</td><td>121</td><td>5.0 (1.0–7.0)</td><td>107</td><td>2.0 (0.0–5.0)</td></tr><tr><td>Doubts about treatments (0–10)<sup>b</sup></td><td>159</td><td>4.0 (1.0–5.0)</td><td>121</td><td>3.0 (1.0–5.0)</td><td>105</td><td>3.0 (1.0–5.0)</td></tr><tr><td>Conspiracy theories (0–10)<sup>b</sup></td><td>155</td><td>5.0 (4.0–8.0)</td><td>116</td><td>5.0 (4.0–8.0)</td><td>104</td><td>5.0 (3.0–7.0)</td></tr></tbody></table>

IQR: interquartile range; axSpA: axial spondyloarthritis; RA: rheumatoid arthritis; HOA: hand osteoarthritis; high education level (university) vs. low education level (primary or secondary school); SPS: socio-professional status; high SPS: executives and higher intellectual professions, low SPS: all other professions; BMI: body mass index; IBD: inflammatory bowel disease; immunopositive: positive for rheumatoid factor and/or ACPA positive, ASDAS: Ankylosing Spondylitis Disease Activity Score; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; CRP: C-reactive protein; DAS28: Disease Activity Score; FIHOA: Functional Index for HOA; NSAIDs: non-steroidal inflammatory drugs; cDMARDs: conventional disease-modifying anti-rheumatic drugs; bDMARDs: biologic disease-modifying anti-rheumatic drugs; JAKi: Janus kinase inhibitor; SC: subcutaneous; IV: intravenous; RAID: rheumatoid arthritis impact of disease; FIRST: fibromyalgia rapid screening tool (score ≥ 5/6, fibromyalgia very likely); CAM: complementary and alternative medicine. Medication adherence: Have you ever forgotten to take your medication on time? And have you ever taken a break (i.e., stopped taking your medication) without its being recommended by a doctor?

a

Number of available data.

b

High score indicates poor score.

c

High score indicates better score.

Patients' beliefs were assessed according to those most usually found in the general population or patients with RMDs. Positive health beliefs were explored by the level of agreement to the statement "In general, I think that physical activity is beneficial for my rheumatism." (0, not at all, to 10, yes, absolutely), which is part of the Questionnaire for Arthritis Dialogue [7]. Negative health beliefs were assessed by the mean responses to 3 statements (response 0, not at all, to 10, yes, absolutely): "In general, I have some doubts about vaccines." [7]; "In general, I think that medications do more harm than good." (from a quantitative study of patients' medication adherence in IA [25]); and "In general, I think that the official version of events given by the authorities very often hides the truth." (a single-item scale measuring belief in conspiracy theories [26]).
## 2.4. Statistical analysis

### 2.4.1. Sample size calculation

No statistical assumptions were made. Assuming that 40% of the patients were or had been on a diet and considering a 6-month period of enrolment, we estimated the number of patients to include at 600 patients, 200 patients in each RMD group (RA, axSpA, and HOA).

### 2.4.2. Descriptive analyses

Baseline characteristics were reported globally and for each disease population, using frequencies and percentages for categorical data and mean ± SD or median (interquartile range [IQR]) for continuous data, according to their distribution.

### 2.4.3. Primary outcome

The primary outcome was the proportion of patients who had been or were on diet, for the whole population and for each RMD.

### 2.4.4. Secondary outcome

Secondary outcomes were the type of diet followed for each RMD. For each diet, the number of patients with current or past diets was divided by the total number of diets followed (e.g., if a patient indicated 3 different types of diet, this was 3 diets in the total number of diets followed). Analysis of the effect of food and beverages involved patients who indicated at least one food or beverage modifying their pain.

For each disease, we used unadjusted logistic regression models to investigate: (1) factors associated with current or past dieting and (2) the perceived effect of dietary components on pain. Studied variables were age, sex, BMI, education level, socio-professional status, presence of digestive disease, RAID score, FIRST score, positive beliefs about physical activity, negative beliefs, active disease, perceived level of information about disease and treatment, perceived support from relatives and physicians, use of CAM, alcohol and tobacco consumption and Groll comorbidity index. The unadjusted analyses selected factors associated with at least one of the 2 events with a cut-off of *P* < 0.15. Then, we used the population with all available selected factors to build the adjusted models, systematically adjusting for age and including selected covariates. Results are expressed as odds ratios (ORs) with 95% confidence intervals (CIs). *P* < 0.05 indicated statistical significance. All analyses were performed with SAS 9.4 (SAS Institute Inc., Cary, NC).

## 2.5. Role of the funding source

The sponsor was AP-HP (Délégation à la recherche clinique et à l'innovation) and the study was funded by a grant from the AERER association (Association d'enseignement et de recherche en rhumatologie), Hôpital Saint-Antoine, Paris.

# 3. Results

## 3.1. Patients

From among the 448 patients included, 56 were excluded from the analysis because they did not complete the dietary questionnaire (n = 3) or the food/beverage questionnaire was not or was poorly completed (n = 51) or other questionnaires were missing (n = 2). Thus data for 392 patients were analysed: 161 patients with axSpA, 123 with RA, and 108 with HOA (supplementary material 2). Patient characteristics are in Table 1. RA and HOA patients were mostly women: 104 (84.6%) and 91 (84.3%) respectively; 94 (58.4%) axSpA patients were men. All patients had long-standing disease (median duration 11 years [IQR 7.0–20.0]); 109 (68.1%) axSpA patients had peripheral involvement and 73 (67.6%) HOA patients also had OA in other sites. The mean BMI was 25.0 ± 4.7 kg/m²; 48 (12.7%) patients were obese (BMI ≥ 30 kg/m²).
In the total sample, 11 (2.8%) patients followed a salt-free diet and 13 (3.3%) a diabetic diet. A high proportion of axSpA and RA patients received targeted treatments: 113 (72.4%) and 104 (86.7%). For patients with RA, only 22 (18.8%) had active disease, with DAS28-CRP ≥ 3.2) whereas for 77 (49.7%) axSpA patients, the BASDAI was ≥ 4/10. Overall, 42 (27.5%) of axSpA patients versus 17 (14.7%) of RA patients and 10 (10%) of HOA patients had positive screening results for fibromyalgia; 121 (31.0%) of all patients had used CAM.

## 3.2. Primary outcome

Of the 392 patients, 102 (26.0%) had been or were on a diet: 49 with axSpA (30.4%), 29 with RA (23.6%) and 24 with HOA (22.2%).

Regarding the distribution of diets (Fig. 1), the cow's milk-free diet was the one followed by patients with IA (24.6% of all diets for RA and 26.5% for axSpA) as was the gluten-free diet (24.6% and 25.6%) whereas the cow's milk-free diet (28.6%) and the detox/fasting diet (26.2%) were the most popular among HOA patients. All reported diets were exclusion diets, except for the Mediterranean diet, representing only 5.1% of diets (2.6% for axSpA, 4.8% for HOA and 10.5% for RA). The median duration of diets was 12 months (IQR 4.0–30.0), with a median of 6 months for the gluten-free diet (IQR 3.0–36.0) and a maximum of 24 months for the vegetarian diet (IQR 8.0–78.0) (Table 2).

<figure><img src="image_7.png" /></figure>

1. Download: [Download high-res image (469KB)](https://i.imgur.com/45678.png)

2. Download: [Download full-size image](https://i.imgur.com/45678.png)

Fig. 1. Distribution of diets in relation to all diets followed by patients in each rheumatic and musculoskeletal disease. Percentages not included on the figure: for axSpA: Mediterranean and vegan diets: 2.6% (n = 3) of patients. For HOA: Seignalet diet 2.4% (n = 1). Note: 3 of the 4 patients with non-celiac gluten sensitivity had tried a gluten-free diet and 3 of the 6 lactose-intolerant patients had followed a cow's milk- or lactose-free diet. These 6 patients were excluded. axSpA: axial spondyloarthritis; RA: rheumatoid arthritis; HOA: hand osteoarthritis.

Table 2. Perceived effects of diets (current or past) and diet duration.
<table><thead><tr><th rowspan="2">Diets</th><th rowspan="2">Patients on diet</th><th colspan="3">Diet</th><th rowspan="2">"Diet decreases my tiredness"</th><th rowspan="2">"Diet improves my general state"</th><th rowspan="2">Duration of diet (months)</th><th rowspan="2">Median (IQR)</th></tr><tr><th>No.<sup>a</sup></th><th>No./No.<sup>a</sup> (%)</th><th>No./No.<sup>a</sup> (%)</th><th>No./No.<sup>a</sup> (%)</th><th>No./No.<sup>a</sup> (%)</th></tr></thead><tbody><tr><td>All diets</td><td>216</td><td>2/187 (1.1)</td><td>96/187 (51.3)</td><td>89/187 (47.6)</td><td>68/199 (34.2)</td><td>124/200 (62.0)</td><td>142</td><td>12.0 (4.0-30.0)</td></tr><tr><td>Cow's milk-free diet</td><td>57</td><td>0/53 (0)</td><td>30/53 (56.6)</td><td>23/53 (43.4)</td><td>14/54 (25.9)</td><td>32/54 (59.3)</td><td>40</td><td>12.0 (4.5-36.0)</td></tr><tr><td>Gluten-free diet</td><td>49</td><td>0/48 (0)</td><td>29/48 (60.4)</td><td>19/48 (39.6)</td><td>21/48 (43.8)</td><td>28/48 (58.3)</td><td>35</td><td>6.0 (3.0-36.0)</td></tr><tr><td>Detox/fasting</td><td>32</td><td>0/23 (0)</td><td>9/23 (39.1)</td><td>14/23 (60.9)</td><td>8/30 (26.7)</td><td>22/30 (73.3)</td><td>21</td><td>9.0 (4.0-15.0)</td></tr><tr><td>Lactose-free diet</td><td>29</td><td>0/27 (0)</td><td>15/27 (55.6)</td><td>12/27 (44.4)</td><td>9/26 (34.6)</td><td>16/26 (61.5)</td><td>19</td><td>12.0 (5.0-36.0)</td></tr><tr><td>"Seignalet" diet</td><td>17</td><td>0/14 (0)</td><td>8/14 (57.1)</td><td>6/14 (42.9)</td><td>7/16 (43.8)</td><td>10/16 (62.5)</td><td>11</td><td>6.0 (3.0-24.0)</td></tr><tr><td>Vegetarian diet</td><td>16</td><td>1/12 (8.3)</td><td>3/12 (25.0)</td><td>8/12 (66.7)</td><td>5/14 (35.7)</td><td>7/14 (50.0)</td><td>11</td><td>24.0 (8.0-78.0)</td></tr><tr><td>Mediterranean diet</td><td>11</td><td>1/7 (14.3)</td><td>1/7 (14.3)</td><td>5/7 (71.4)</td><td>3/8 (37.5)</td><td>7/9 (77.8)</td><td>3</td><td>{1.0; 12.0; 30.0}</td></tr><tr><td>Vegan diet</td><td>5</td><td>0/3 (0)</td><td>1/3 (33.3)</td><td>2/3 (66.7)</td><td>1/3 (33.3)</td><td>2/3 (66.7)</td><td>2</td><td>{2.0; 24.0}</td></tr></tbody></table>

No.<sup>a</sup>: number with available data (population following a diet); {}: raw data.

Of the 102 patients who had tried a diet, 100 responded to the question regarding the advice they had received: 47 had found information or advice on the Internet or social media, in the press or on television, and 45 were advised by family, friends, or other patients; 29 were informed or counselled by a dietician or another HP and only 18 by a medical physician. RA patients had received more nutritional advice from dieticians (11/24 [41%]) or physicians (7/27 [26%]) than axSpA patients (12/49 [24%] and 9/49 [18%]) and HOA patients (6/24 [25%] and 2/24 [8%]).

## 3.3. Secondary outcomes

### 3.3.1. Perceived effect of diets

For all followed diets, 51.3% of patients reported a decrease in pain, 34.2% a decrease in fatigue, and 62.0% an improvement in general condition (Table 2). However, 47.6% of patients reported no change in pain. In patients' opinion, the cow's milk-free, gluten-free, lactose-free and Seignalet diets most reduced pain (56.6%, 60.4%, 55.6% and 57.1% of patients, respectively). The detox/fasting diet did not modify pain for 60.9% of patients but improved the general condition for 73.3%.
3.3.2. Perceived effect of food and beverages

Of the 365 patients who responded to this question, 182 (49.9%) found that in general, dietary
components modified symptoms of their rheumatic disease (47.0% for RA, 47.4% for HOA, and 53.6%
for axSpA), whereas 29.9% had no opinion. In addition, 165/392 patients (42.1%) specifically identified
at least one food or beverage having an effect on pain (positive or negative).

Patients' opinion of foods, beverages, dietary supplements or food categories regarding their impact
on pain are in supplementary material 1. The top 10 pain-relieving or -worsening dietary components
are in Fig. 2. Patients' opinion did not differ substantially by type of RMD. The most-often pain-
relieving foods were green vegetables, fatty fish, turmeric, olive oil, and foods rich in omega-3.

Conversely, the most-often pain-worsening foods were dairy products, strong alcohol, wine and beer,
delicatessen foods, and red meat. However, patients' views were heterogenous: when considering a
particular food or drink, more than 80% of patients did not report any impact on pain.
<figure><img src="image_8.png" /></figure>

<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /></figure>
Fig. 2. Top 10 foods/drinks that worsened pain (red) or relieved pain (green) in patients with axSpA (A), RA (B), HOA (C). Analyses performed on the 165 patients who reported that at least one food/drink modified pain. axSpA: axial spondyloarthritis; RA: rheumatoid arthritis; HOA: hand osteoarthritis.

### 3.3.3. Factors associated with current or past diets

In the adjusted analysis (Table 3), for RA patients, current or past diet practice was associated with belonging to a high socio-professional status with or without a high level of education versus low education level (primary or secondary level) (OR 6.1 [95% CI 1.5 to 25.4] and OR 5.6 [95% CI 1.4 to 22.3]). Also, dieting was associated with believing in the benefits of physical activity for their arthritis (OR 3.30 [95% CI 1.1 to 10.3]). For axSpA patients, dieting was associated with only use of CAM (OR 3.6 [95% CI 1.6 to 7.9]). For HOA patients, it was associated with having a gastrointestinal disease, using CAM, and negative beliefs (OR 6.0 [95% CI 1.7 to 21.4]), 4.8 [95% CI 1.6 to 14.7], and 3.1 [95% CI 1.0 to 9.3], respectively).

<table><caption>Table 3. Factors associated with dieting or having followed a diet in RA, axSpA and HOA.</caption><thead><tr><th rowspan="2">Diseases</th><th rowspan="2">Variable</th><th>Unadjusted model</th><th>Adjusted model<sup>a</sup></th></tr><tr><th>OR (95% CI)</th><th>OR (95% CI)</th></tr></thead><tbody><tr><td rowspan="10">RA</td><td>High education level and high SPS</td><td></td><td></td></tr><tr><td>Low education level</td><td>1</td><td>1</td></tr><tr><td>High education level and low SPS</td><td>8.61 (2.63 to 28.19)**</td><td>5.62 (1.42 to 22.26)*</td></tr><tr><td>High education level and high SPS</td><td>7.38 (2.30 to 23.70)**</td><td>6.13 (1.48 to 25.35)*</td></tr><tr><td>Positive beliefs (physical activity is beneficial) (yes vs. no)</td><td>2.96 (1.16 to 7.53)</td><td>3.30 (1.06 to 10.27)*</td></tr><tr><td>“Feels poorly informed about disease and treatment” (yes vs. no)</td><td>2.73 (1.10 to 6.80)</td><td>2.65 (0.84 to 8.29)</td></tr><tr><td>“Feels poorly supported by relatives” (yes vs. no)</td><td>3.30 (1.25 to 8.76)</td><td>3.39 (0.93 to 12.30)</td></tr><tr><td>Use of CAM (yes vs. no)</td><td>4.64 (1.84 to 11.68)**</td><td>2.03 (0.66 to 6.23)</td></tr><tr><td>High education level and high SPS</td><td></td><td></td></tr><tr><td>Low education level</td><td>1</td><td>1</td></tr><tr><td rowspan="7">axSpA</td><td>High education level and low SPS</td><td>1.50 (0.56 to 4.03)</td><td>1.54 (0.51 to 4.65)</td></tr><tr><td>High education level and high SPS</td><td>2.32 (0.97 to 5.55)</td><td>2.31 (0.90 to 5.92)</td></tr><tr><td>Not available</td><td>1.68 (0.37 to 7.55)</td><td>1.49 (0.30 to 7.46)</td></tr><tr><td>“Feels poorly supported by physician” (yes vs. no)</td><td>2.43 (0.82 to 7.18)</td><td>2.24 (0.63 to 7.93)</td></tr><tr><td>“Feels poorly supported by relatives” (yes vs. no)</td><td>2.78 (1.21 to 6.37)</td><td>2.38 (0.95 to 5.94)</td></tr><tr><td>Use of CAM (yes vs. no)</td><td>3.87 (1.82 to 8.24)**</td><td>3.59 (1.63 to 7.89)*</td></tr></tbody></table>
<table><thead><tr><th rowspan="2">Diseases</th><th rowspan="2">Variable</th><th>Unadjusted model</th><th>Adjusted model<sup>a</sup></th></tr><tr><th>OR (95% CI)</th><th>OR (95% CI)</th></tr></thead><tbody><tr><td rowspan="4">HOA</td><td>At least one gastrointestinal disease (yes vs. no)</td><td>3.54 (1.25 to 9.99)</td><td>5.99 (1.68 to 21.40)*</td></tr><tr><td>Negative beliefs (yes vs. no)</td><td>2.56 (0.97 to 6.73)</td><td>3.08 (1.02 to 9.30)*</td></tr><tr><td>Use of CAM (yes vs. no)</td><td>4.22 (1.59 to 11.20)*</td><td>4.80 (1.56 to 14.73)*</td></tr><tr><td>Current alcohol consumption (yes vs. no)</td><td>3.38 (0.72 to 15.76)</td><td>5.01 (0.91 to 27.65)</td></tr></tbody></table>

Analyses involved using logistic regression for a total of 114 RA patients, 101 HOA patients (population with data available for all variables) and 151 axSPA patients (population with data available for all variables, except for SPS and high education level, for which a "not available" category was created). OR: odds ratio95% CI: 95% confidence interval; RA: rheumatoid arthritis; axSpA: axial spondyloarthritis; HOA: hand osteoarthritis; SPS: socio-professional status; CAM: complementary and alternative medicine. High education level: university; low education level: primary or secondary school; SPS: socio-professional status; high SPS: executives and higher intellectual professions; low SPS: all other professions; positive beliefs (physical activity is beneficial): yes = median score ≥ 9/10; "feels poorly informed about disease and treatment": yes = median score < 8/10; "feels poorly supported by relatives": yes = not at all/fairly little vs. no = quite often/often; use of CAM: yes = use of at least one CAM; "feels poorly supported by doctor": yes = "not at all/fairly little" vs. no = "quite often/often"; negative beliefs: yes = median score ≥ 4/10.

a

Model adjusted on co-variable and age.

*

$P < 0.05.$

**

$P < 0.01.$

### 3.3.4. Factors associated with perceived effect of dietary components on pain

In the adjusted analysis (Table 4), for RA patients, experiencing an impact of a dietary component on pain was associated with believing in the benefits of physical activity for their arthritis and feeling poorly supported by their relatives (OR 3.1 [95% CI 1.3 to 7.3] and OR 3.6 [95% CI 1.3 to 10.4]). For axSpA patients, this experience was associated with having active disease (OR 2.6 [95% CI 1.2 to 5.8]) and feeling poorly informed about the disease or treatments (OR 2.1 [95% CI 1.0 to 4.3]). No associated factors were found for HOA patients.

<table><caption>Table 4. Factors associated with the presence of at least one food/beverage having a perceived effect on pain.</caption><thead><tr><th rowspan="2">Diseases</th><th rowspan="2">Variable</th><th>Unadjusted model</th><th>Adjusted model<sup>a</sup></th></tr><tr><th>OR (95% CI)</th><th>OR (95% CI)</th></tr></thead><tbody><tr><td rowspan="4">RA</td><td>Overweight or obese (yes vs. no)</td><td>0.49 (0.23 to 1.05)</td><td>0.44 (0.19 to 1.02)</td></tr><tr><td>Positive beliefs (physical activity is beneficial) (yes vs. no)</td><td>2.44 (1.12 to 5.32)</td><td>3.07 (1.28 to 7.32)*</td></tr><tr><td>"Feels poorly supported by relatives" (yes vs. no)</td><td>2.94 (1.17 to 7.42)</td><td>3.62 (1.26 to 10.43)*</td></tr><tr><td>Use of CAM (yes vs. no)</td><td>2.72 (1.20 to 6.18)</td><td>1.91 (0.78 to 4.72)</td></tr></tbody></table>
<table><thead><tr><th rowspan="2">Diseases</th><th rowspan="2">Variable</th><th>Unadjusted model</th><th>Adjusted model<sup>a</sup></th></tr><tr><th>OR (95% CI)</th><th>OR (95% CI)</th></tr></thead><tbody><tr><td rowspan="10">axSpA</td><td>High education level and high SPS</td><td></td><td></td></tr><tr><td>Low education level</td><td>1</td><td>1</td></tr><tr><td>High education level and low SPS</td><td>2.12 (0.90 to 5.01)</td><td>1.58 (0.61 to 4.15)</td></tr><tr><td>High education level and high SPS</td><td>1.63 (0.75 to 3.56)</td><td>1.68 (0.72 to 3.93)</td></tr><tr><td>Not available</td><td>2.55 (0.64 to 10.14)</td><td>2.30 (0.54 to 9.80)</td></tr><tr><td>Active disease (yes vs. no)</td><td>2.31 (1.10 to 4.86)</td><td>2.62 (1.17 to 5.84)*</td></tr><tr><td>Feels poorly informed about disease and treatment (yes vs. no)</td><td>2.03 (1.05 to 3.89)</td><td>2.11 (1.04 to 4.30)*</td></tr><tr><td>Use of CAM (yes vs. no)</td><td>1.85 (0.92 to 3.76)</td><td>1.93 (0.90 to 4.15)</td></tr><tr><td>High education level and high SPS</td><td>—</td><td>—</td></tr><tr><td>Low education level</td><td>1</td><td>1</td></tr><tr><td rowspan="7">HOA</td><td>High education and low SPS</td><td>2.34 (0.72 to 7.61)</td><td>1.85 (0.53 to 6.46)</td></tr><tr><td>High education and high SPS</td><td>2.93 (1.14 to 7.51)</td><td>2.26 (0.84 to 6.10)</td></tr><tr><td>Not available</td><td>1.32 (0.21 to 8.25)</td><td>1.08 (0.16 to 7.14)</td></tr><tr><td>Positive beliefs (physical activity is beneficial) (yes vs. no)</td><td>2.58 (1.11 to 6.00)</td><td>1.96 (0.79 to 4.84)</td></tr><tr><td>Current alcohol consumption (yes vs. no)</td><td>3.66 (1.13 to 11.84)</td><td>2.80 (0.82 to 9.57)</td></tr></tbody></table>

Analyses involved using logistic regression with a total of 114 RA patients, 101 HOA patients (population with data available for all variables) and 151 axSpA patients (population with data available for all variables, except for SPS and high education level for which a "not available" category was created). OR: odds ratio95% CI: 95% confidence interval; RA: rheumatoid arthritis; axSpA: axial spondyloarthritis; HOA: hand osteoarthritis; SPS: socio-professional status; CAM: complementary and alternative medicine. Overweight or obese: yes = BMI > 25 g/cm²; positive beliefs (physical activity is beneficial): yes = median score ≥ 9/10; "feels poorly supported by relatives": yes = "not at all/fairly little" vs. no = "quite often/often"; "feels poorly informed about disease and treatment": yes = median score < 8/10; use of CAM: yes = use of at least one CAM; high education level: university; low education level: primary or secondary school; high SPS: executives and higher intellectual professions, low SPS: all other professions; active disease: yes = BASDAI score ≥ 4/10 or ASDAS ≥ 1.3.

a

Model adjusted on: co-variable and age.

*

P < 0.05.
4. Discussion

This study reports the dietary practices of patients with RA, axSpA and HOA and the perceived effects
of diets and food on rheumatic symptoms and associated factors. In this study, 26% of patients were
following or had followed at least one diet, with a slightly higher rate of dieting in axSpA patients (30%)
than other patients. In total, 42% of patients reported that at least one food or beverage had an impact
on pain.

The rate of our patients trying diets are in line with those of the 2 published studies on the topic [6], [9] and does not seem to change much over time: 24% to 32% of patients with axSpA and RA had been on a gluten-free diet in the recent French study [9] and 10% on a fasting diet. Also, in a study conducted in Norway 30 years ago, 23% of patients with RA, SpA or fibromyalgia had previously tried certain diets [6], and 14% had tried fasting.

The present study asked for nearly all possible diets with a specific list of 8 exclusion diets patients could have been exposed to. The gluten- or cow's milk-free diets were the most followed by patients with IA and the cow's milk-free and detox/fasting diets by HOA patients, with a median duration of all diets of 12 months.

The Mediterranean diet is recommended for the general population [27] and for patients with RMDs [4], [5] but was only followed by 5% of patients in this study. The rate of Mediterranean diet adherence seems low in this study and was certainly underestimated. In two French cohort studies dedicated to estimating the adherence to the Mediterranean diet, the rate of high adherence was 13% and 31%, with a rate of 29% in patients with psoriasis [28], [29].

Although not recommended, all the other diets in the present study were exclusion diets. Because the involvement of physicians did not exceed 18%, physicians may not have had enough opportunities to counteract unverified information about restrictive diets [30] commonly conveyed to the general population. Advice from dietitians and rheumatologists was slightly higher for RA patients than other patients, possibly because of frequent prescription of corticosteroids in RA (40% of patients in this study) requiring specific hygienic and dietary measures and the greater development of patient education programmes in RA than in other RMDs.

We describe for the first time factors for dietary practices. Dieting in RA patients was associated with a positive health belief, such as with the benefits of exercise. Dieting may be a part of a positive coping strategy of trying all possible lifestyle changes in order to feel better, as has been observed in patients with RA and breast cancer [31]. At the same time, motivations for lifestyle changes may increase the vulnerability to fake news about food [32]. HOA patients exhibited negative health beliefs associated with dieting. Negative beliefs included doubts about vaccines and medications as well as a tendency to believe in conspiracy theories, which have been associated with dietary changes in American adults [33]. The use of CAM was associated with diets for axSpA and HOA patients but not RA patients. However, this last result is possibly due to insufficient statistical power: in the study by Callahan et al., including 2140 patients, people using CAM also tried some specific diets and were in high socio-professional categories [34]. Some restrictive diets such as gluten-free diets have financial costs that only people in high socio-professional categories can probably afford.

In the present study, 42% of patients identified that at least one food or beverage had an effect on pain. Some foods were pain relieving, such as green vegetables, fruits, and fatty fish, and could be considered "anti-inflammatory". In a meta-analysis, consuming specific dietary components did not affect pain or function in rheumatic diseases [4]. In an American study [8], 40% of Hispanic patients with inflammatory diseases reported that fruit and vegetables improved symptoms, whereas red meat and alcohol worsened them.

Patients' opinions on dietary components can also be influenced by recommendations of nutritional habits disseminated to the general population for preventing cardiovascular risk [35]. These recommendations were not published at the time of our study. This study also highlighted the cultural significance of food according to various geographical backgrounds: cow's milk, alleged to increase pain in our study, had no effect in an American population [8], [36].

The health beliefs associated with patients' views on the impact of dietary components on pain were the positive perception of exercise for RA patients and the lack of support or information for both axSpA and RA patients. No such factors were found for HOA patients, although they were less informed and had experienced less support. Patients with active axSpA were more likely to find an effect of food, but because the effect could be positive or negative, this factor is inconclusive. Notably, in a cohort of SpA patients, the study by Vergne Salle et al. [37] found high disease activity associated with high intake of ultra-processed foods, but the present study did not test this food item.
The strengths of the study include the multicentre design, the substantial number of patients included (although the study was prematurely stopped due to the COVID-19 pandemic), the reliability of data collected by the rheumatologists, the wide range of diets explored, and the list of foods, drinks, dietary supplements and components tested close to exhaustivity. The potential factors assessed for diets and dietary perceptions went beyond the usual patient and disease characteristics and included health beliefs and patient experiences.

This study has limitations. Although the list of diets was extensive, the list of foods did not include ultra-processed food products, which have an impact on the gut [38]. Because of the length of the list, the diets were not detailed, which could lead to an underestimation of adherence to certain diets, such as the Mediterranean diet, whose rate was low in this study. The patient sample was mostly followed in hospitals, with a large proportion of IA patients under targeted treatment, which does not recapitulate the entire IA population. In addition, patients were included on a voluntary basis, which may have led to a selection bias on patients already sensitized to the subject of nutrition and an overestimation of the proportion of patients who were or had been on a diet.

The factors identified represent associated factors but not causality because of the cross-sectional survey design. As mentioned above, the target number of patients (n = 600) was not reached, which may have led to lack of power in identifying certain factors.

In conclusion, the present study showed that 26% of patients with RMDs had tried an exclusion diet. Some patients identified potentially pro- or anti-inflammatory foods they consumed, but they rarely followed the Mediterranean diet. Patients' health beliefs, the use of complementary and alternative medicines, and lack of support or information from HPs were the main associated factors.

## Funding

The sponsor was Assistance publique-Hôpitaux de Paris (Délégation à la recherche clinique et à l'innovation) and the study was funded by a grant from the AERER association (Association d'enseignement et de recherche en rhumatologie) Hôpital Saint-Antoine, Paris.

## Authors' contributions

Concept and design: Jérémie Sellam, Catherine Beauvais, Alexandre Rousseau, Chloé Jamakorzyan.

Acquisition, analysis or interpretation of data: all authors.

Drafting of the manuscript: Domitille Renard, Catherine Beauvais, Jérémie Sellam.

Critical revision of the manuscript for important intellectual content: all authors.

Statistical analysis: Sophie Tuffet, Alexandra Rousseau.

Obtaining funding: Jérémie Sellam.

Supervision: Jérémie Sellam, Catherine Beauvais, Alexandra Rousseau, Domitille Renard.

## Disclosure of interest

The authors declare that they have no competing interest.

## Disclosure of interest apart from the study

Pascal Claudepierre received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Abbvie, UCB, Pfizer, Lilly, Novartis, Janssen, MSD, Celltrion, Biogen; received support for attending meetings and/or travel from Abbvie, UCB, Pfizer, Novartis, Janssen, Amgen; and participated on a Data Safety Monitoring Board or Advisory Board for Abbvie, UCB, Lilly, Novartis, Janssen, MSD, Celltrion.

Bruno Fautrel has received research grants from AbbVie, Lilly, MSD and Pfizer, and consultancy fees from AbbVie, Amgen, Biogen, BMS, Celltrion, Chugai, Fresenius Kabi, Galapagos, Janssen, Lilly, Medac, MSD, NORDIC Pharma, Novartis, OWKIN, Pfizer, Roche, Sandoz, Sanofi-Genzyme, SOBI, UCB, Viatris.

Emmanuel Maheu received fees from FIDIA, TRB Chemedica, IBSA, Pierre Fabre, SUBLIMED and Expanscience and received support for attending meetings and/or travel from FIDIA, TRB Chemedica and IBSA.

Claire Carette received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from NovoNordisk, Lilly, AstraZeneca, Novartis, IPSEN, MSD, Publicis Health, Pfizer, Boehringer; received support for attending meetings and/or travel from
NovoNordisk, Lilly, AstraZeneca, Sanofi, MSD, Vitalaire, Rhythm, Boehringer; and participated on a Data Safety Monitoring Board or Advisory Board for Bioproject Pharma.

Sébastien Czernichow received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Fresenius Novonordisk, Lilly, BMS, Boehringer, Novartis and Janssen; received support for attending meetings and/or travel from NovoNordisk, and participated on a Data Safety Monitoring Board or Advisory Board for Lilly, Novonordisk, Fresenius, Bariatek; he holds stock or stock options at Jellynov, Alifert and mygoodlife.

Catherine Beauvais declares research grants from Viatris, BMS, Lilly, and Fresenius-Kabi and received fees from Viatris, Fresenius-Kabi, Sandoz, Novartis, Nordic, Galapagos, Janssen, UCB, MSD, Sanofi and Lilly as an occasional speaker or participation on a medical board or educational events.

## Acknowledgements

We thank the patients who participated in the study, the medical team from the rheumatology departments of Saint-Antoine Hospital (Juliette-Louise Petit, Julien Champey, Sandra Desouches, Alice Courties, Ariane Do, Sabine Trellu), the clinical research team URCEST (Amel Touati, Dehia Kabbiche), and Laura Smales for reviewing the English version (BioMedEditing, Toronto, Canada).

## References

1. [1]C. Daien, C. Hua, C. Gaujoux-Viala, et al.
Update of French Society for Rheumatology recommendations for managing rheumatoid arthritis
Joint Bone Spine, 86 (2019), pp. 135-150
View PDFView articleView in ScopusGoogle Scholar

2. [2]D. Wendling, S. Hecquet, O. Fogel, et al.
2022 French Society for Rheumatology (SFR) recommendations on the everyday management of patients with spondyloarthritis, including psoriatic arthritis
Joint Bone Spine, 89 (2022), p. 105344
View PDFView articleView in ScopusGoogle Scholar

3. [3]M. Kloppenburg, F.P. Kroon, F.J. Blanco, et al.
2018 update of the EULAR recommendations for the management of hand osteoarthritis
Ann Rheum Dis, 78 (2019), pp. 16-24
View PDFView articleCrossrefView in ScopusGoogle Scholar

4. [4]J.M. Gwinnutt, M. Wieczorek, A. Balanescu, et al.
2021 EULAR recommendations regarding lifestyle behaviours and work participation to prevent progression of rheumatic and musculoskeletal diseases
Ann Rheum Dis, 82 (2022), pp. 48-56
Google Scholar

5. [5]C. Daien, S. Czernichow, J.G. Letarouilly, et al.
Dietary recommendations of the French Society for Rheumatology for patients with chronic inflammatory rheumatic diseases
Joint Bone Spine, 89 (2022), p. 105319

6. [6]M. Haugen, J. Kjeldsen-Kragh, B.Y. Nordvåg, et al.
Diet and disease symptoms in rheumatic diseases – results of a questionnaire based survey
Clin Rheumatol, 10 (1991), pp. 401-407

7. [7]L. Gossec, F. Berenbaum, P. Chauvin, et al.
Development and application of a questionnaire to assess patient beliefs in rheumatoid arthritis and axial spondyloarthritis
Clin Rheumatol, 37 (2018), pp. 2649-2657

8. [8]S. Lee, J. Rodman, V. Hsu, et al.
Beliefs, experiences, and openness regarding dietary interventions: data from an urban U.S. Hispanic rheumatic disease population
Arthritis Care Res, 75 (2023), pp. 2207-2214, 10.1002/acr.25128
[acr.25128]

9. [9]T. Pham, H. Sokol, B. Halioua, et al.
Immune-mediated inflammatory diseases and nutrition: results from an online survey on patients' practices and perceptions

BMC Nutr, 7 (2021), p. 38

10. [10]L. Perrin, B. Allès, C. Buscail, et al.
Gluten-free diet in French adults without coeliac disease: sociodemographic characteristics, motives and dietary profile

Br J Nutr, 122 (2019), pp. 231-239

11. [11]Y. Hu, K.H. Costenbader, X. Gao, et al.
Sugar-sweetened soda consumption and risk of developing rheumatoid arthritis in women

Am J Clin Nutr, 100 (2014), pp. 959-967

12. [12]M. Breban
Gut microbiota and inflammatory joint diseases

Joint Bone Spine, 83 (2016), pp. 645-649

13. [13]A. Ortolan, M. Felicetti, M. Lorenzin, et al.
The impact of diet on disease activity in spondyloarthritis: a systematic literature review

Joint Bone Spine, 90 (2023), p. 105476

14. [14]D. Ramachandran, J. Kite, A.J. Vassallo, et al.
Food trends and popular nutrition advice online – implications for public health

Online J Public Health Inform, 10 (2018), p. e.213

Google Scholar

15. [15]D. Aletaha, T. Neogi, A.J. Silman, et al.
2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative
Arthritis Rheum, 62 (2010), pp. 2569-2581

CrossrefView in Scopus

16. [16]M. Rudwaleit, D. van der Heijde, R. Landewe, et al.
The Assessment of SpondyloArthritis international Society classification criteria for peripheral spondyloarthritis and for spondyloarthritis in general

Ann Rheum Dis. 70 (2011), pp. 25-31

View PDFView articleCrossrefView in Scopus

17. [17]R. Altman, G. Alarcón, D. Appelrouth, et al.
The American College of Rheumatology criteria for the classification and reporting of osteoarthritis of the hand

Arthritis Rheum, 33 (1990), pp. 1601-1610

CrossrefView in Scopus

18. [18]A.V. Klein, H. Kiat
Detox diets for toxin elimination and weight management: a critical review of the evidence

J Hum Nutr Diet, 28 (2015), pp. 675-686

19. [19]J. Seignalet
Diet, fasting, and rheumatoid arthritis

Lancet, 339 (1992), pp. 68-69

Google Scholar

20. [20]
D. Groll, T. To, C. Bombardier, et al.
The development of a comorbidity index with physical function as the outcome
J Clin Epidemiol, 58 (2005), pp. 595-602

View PDFView articleView in Scopus

21. [21]
L. Gossec, S. Paternotte, G.J. Aanerud, et al.

Finalisation and validation of the rheumatoid arthritis impact of disease score, a patient-
derived composite measure of impact of rheumatoid arthritis: a EULAR initiative

Ann Rheum Dis, 70 (2011), pp. 935-942

View PDFView articleCrossrefView in ScopusGoogle Scholar

22. [22]

S. Perrot, D. Bouhassira, J. Fermanian

Development and validation of the Fibromyalgia Rapid Screening Tool (FiRST)

Pain, 150 (2010), pp. 250-256

View PDFView articleCrossrefView in ScopusGoogle Scholar

23. [23]

R.L. Dreiser, E. Maheu, G.B. Guillou, et al.

Validation of an algofunctional index for osteoarthritis of the hand

Rev Rhum Engl Ed, 62 (1995), pp. 43S-53S

Google Scholar

24. [24]

C. Beauvais, F. Fayet, A. Rousseau, et al.

Efficacy of a nurse-led patient education intervention in promoting safety skills of patients with inflammatory arthritis treated with biologics: a multicentre randomised clinical trial

RMD Open, 8 (2022), p. e001828, 10.1136/rmdopen-2021-001828

View in ScopusGoogle Scholar

25. [25]

C. Beauvais, D. Pau, V. Hautin-Monteil, et al.

One-third of patients are low-adherent to methotrexate for rheumatoid arthritis at the initiation of a first biologic. A cross-sectional study investigating adherence rate and factors

Joint Bone Spine, 87 (2020), pp. 668-669

View PDFView articleView in ScopusGoogle Scholar

26. [26]

A. Lantian, D. Muller, C. Nurra, et al.

Measuring belief in conspiracy theories: validation of a French and English single-item scale

Rips, 29 (2016), p. 1

CrossrefView in ScopusGoogle Scholar

27. [27]

High Council for Public Health

French Nutrition and Health Programme's dietary guidelines for adults for the period 2017–2021 (online)

(2017)

https://www.hcsp.fr/explore.cgi/avisrapportsdomaine?clefr=653 (accessed 11 October 2023)

Google Scholar

28. [28]

A. Trébuchet, C. Julia, L. Fézeu, et al.

Prospective association between several dietary scores and risk of cardiovascular diseases: is the Mediterranean diet equally associated to CVD compared to National Nutritional Scores?

Am Heart J, 219 (2019), pp. 1-12

View PDFView articleView in ScopusGoogle Scholar

29. [29]
C. Phan, M. Touvier, E. Kesse-Guyot, et al.
Association between Mediterranean anti-inflammatory dietary profile and severity of psoriasis?
Results from the NutriNet-Santé Cohort
JAMA Dermatol, 154 (2018), pp. 1017-1024
CrossrefView in ScopusGoogle Scholar

30. [30]

F.B. Norwood

Perceived impact of information signals on opinions about gluten-free diets

PLoS One, 16 (2021), p. e0248570, 10.1371/journal.pone.0248570
View in ScopusGoogle Scholar

31. [31]

E. Salminen, S. Heikkilä, T. Poussa, et al.
Female patients tend to alter their diet following the diagnosis of rheumatoid arthritis and breast cancer
Prev Med, 34 (2002), pp. 529-535
View PDFView articleView in ScopusGoogle Scholar

32. [32]G. Castellini, M. Savarese, G. Graffigna

Online fake news about food: self-evaluation, social influence, and the stages of change
moderation

Int J Environ Res Public Health, 18 (2021), p. 2934

33. [33]J.E. Oliver, T. Wood

Medical conspiracy theories and health behaviors in the United States

JAMA Intern Med, 174 (2014), p. 817

34. [34]L.F. Callahan, E.K. Wiley-Exley, T.J. Mielenz, et al.

Use of complementary and alternative medicine among patients with arthritis
Prev Chronic Dis, 6 (2009), p. A44

35. [35]R. Estruch, E. Ros, J. Salas-Salvadó, et al.

Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra-virgin olive oil or nuts
N Engl J Med, 378 (2018), p. e34

36. [36]S.K. Tedeschi, M. Frits, J. Cui, et al.

Diet and rheumatoid arthritis symptoms: survey results from a rheumatoid arthritis registry
Arthritis Care Res (Hoboken), 69 (2017), pp. 1920-1925

37. [37]P. Vergne-Salle, L. Salle, A.C. Fressinaud-Marie, et al.

Diet and disease activity in patients with axial spondyloarthritis: SpondyloArthritis and NUTration study (SANUT)
Nutrients, 14 (2022), p. 4730

38. [38]A. Cuevas-Sierra, F.I. Milagro, P. Aranaz, et al.

Gut microbiota differences according to ultra-processed food consumption in a Spanish population
Nutrients, 13 (2021), p. 2710