# Ultrasonography for the assessment of enthesitis in psoriatic arthritis: systematic review with meta-analysis

Noémie Bibas, Caroline Pignon, Clementina Lopez-Medina, Frédérique Gandjbakhch, Bruno Fautrel, Laure Gossec

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

## To cite this version:

Noémie Bibas, Caroline Pignon, Clementina Lopez-Medina, Frédérique Gandjbakhch, Bruno Fautrel, et al.. Ultrasonography for the assessment of enthesitis in psoriatic arthritis: systematic review with meta-analysis. Rheumatology, 2024, 10.1093/rheumatology/keae705. hal-05000840

HAL Id: hal-05000840

https://hal.science/hal-05000840v1

Submitted on 21 Mar 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished 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>

Distributed under a Creative Commons Attribution 4.0 International License
# Ultrasonography for the assessment of enthesitis in psoriatic arthritis: systematic review with meta-analysis.

## Authors

Noémie Bibas¹,², Caroline Pignon¹, Clementina Lopez-Medina³,⁴, Frédérique Gandjbakhch¹,³, Bruno Fautrel¹,³, Laure Gossec¹,³

## Affiliations

¹Rheumatology Unit, Pitié-Salpêtrière University Hospital, AP-HP, Paris, France.

²Université Paris Cité, F-75006 Paris, France

³Pierre Louis Institute of Epidemiology and Public Health, Sorbonne Université, INSERM, Paris, France.

⁴Reina Sofia University Hospital, IMIBIC, University of Cordoba, Cordoba, Spain

## ORCIDs

N. BIBAS: 0009-0007-0494-4884

C. PIGNON: 0009-0000-1205-5859

C. LOPEZ-MEDINA: 0000-0002-2309-5837

F. GANDJBAKHCH: 0000-0002-3181-4598

B FAUTREL: 0000-0001-8845-4274

L. GOSSEC: 0000-0002-4528-310X

## Corresponding author:

Noémie Bibas, Hôpital Pitié-Salpêtrière, Service de Rhumatologie, 47-83, boulevard de l'Hôpital - 75013 Paris France

Noemie.bibas@aphp.fr, +33 1 42 17 78 14

## Disclosures

N. BIBAS, C. PIGNON: none

C. LOPEZ-MEDINA: has received grants or contracts from AbbVie, Lilly, Novartis, UCB, and Janssen; consulting fees from Lilly, AbbVie, Novartis and UCB; honoraria for lectures from AbbVie, Janssen, Lilly, MSD, Novartis and UCB; has received support for attending meetings and/or travel from MSD, Novartis and UCB.

F. GANDJBAKHCH: none

B. 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.

L. GOSSEC: has received grants or contracts from AbbVie, Biogen, Lilly, Novartis, UCB, consulting fees from AbbVie, BMS, Celltrion, Janssen, Novartis, Pfizer, UCB, honoraria for lectures from AbbVie, Amgen, BMS, Celltrion, Janssen, Lilly, MSD, Novartis, Pfizer, UCB, has received support for attending meetings and/or travel from MSD, Novartis, Pfizer, has received medical writing support from AbbVie, Amgen, Galapagos, Janssen, Pfizer, UCB.

**Funding statement:** No specific funding was received from any bodies in the public, commercial, or not-for-profit sectors to carry out the work described in this article.

**Word count:** 3,109 words, 6 tables, 1 figure, 3 supplementary tables and 2 supplementary figures

**Key words** – psoriatic arthritis, ultrasonography, enthesitis, Sensitivity and Specificity

**Key messages:**

- Ultrasound (US)-detected enthesitis is specific for the diagnosis of psoriatic arthritis (PsA), in healthy subjects, and less so in psoriasis patients.

- Specificity is increased using Power Doppler whatever the comparator group, but sensitivity is low.

- Erosions and Power Doppler at the Achilles tendon sites are rarely found in non-PsA patients.
**Abstract**

**Introduction** The specificity of ultrasonography (US) for enthesitis in psoriatic arthritis (PsA) is unclear. The objective was to analyze the specificity of US enthesitis in Mode B and using Power Doppler (PD), for the diagnosis of PsA through a systematic review with meta-analysis.

**Methods:** Systematic review in PubMed 2010-June 2023, of studies of adult patients with confirmed PsA with or without a control group of non-PsA patients, reporting information on US enthesitis. Data were analyzed on (a) the prevalence of US enthesitis (presence of at least one enthesitis) in PsA patients and non-PsA patients, (b) specificity and sensitivity of US enthesitis and then specifically PD for PsA diagnosis and (c) most specific localizations of enthesitis in PsA patients. Pooled percentages and means were evaluated using univariate random-effects meta-analysis.

**Results** In 76 articles, 5,927 patients with PsA were compared to 3,423 controls (59.0% of whom had psoriasis). The prevalence of US enthesitis was 73.7% [95% confidence interval, 56.6%-90.9%] in PsA patients versus 12.6% [2.6%-22.3%] in controls. The pooled specificity and sensitivity of Mode B US were 73.2% [59.3%-87.0%] and 62.1% [47.9%-76.4%]; and of PD, were 97.9% [96.5%-99.5%] and 14.7% [8.2%-21.2%] respectively. The site most frequently involved in PsA but not in controls was the Achilles tendon, in which erosions and PD activity were most discriminant.

**Conclusion** In this systematic review, US enthesitis was highly prevalent in PsA patients. Evidencing enthesitis by US was found to be reasonably specific and could contribute to the diagnosis of PsA; PD was highly specific, however was rarely present.
**Introduction**

Psoriatic arthritis (PsA) is a chronic, inflammatory disease of the joints, skin and entheses.(1) Enthesitis is considered the hallmark of PsA.(2) Clinical assessment of enthesitis can be challenging since it is based on the subjective presence of pain at pressure. Pain at pressure is not specific to inflammation of the enthesis: mechanical enthesopathy but also widespread pain syndrome can lead to similar symptoms.(3,4) Ultrasound (US) provides a detailed visualization of morphostructural abnormalities(5). US detects in entheses both active inflammation and structural damage.(6) Power-Doppler (PD) is used to inform on vascular changes, as an indication of active inflammation. The definition of US enthesitis, developed by a consensus group, Outcome Measures in Rheumatology (OMERACT), includes an inflammation component (thickness, hypoechogenicity or presence of PD signal) and a structural component (enthesophytes, calcifications or erosions).(7,8) The European Alliance of Associations for Rheumatology (EULAR) advises the use of imaging such as US to detect peripheral enthesitis to support the diagnosis of PsA.(9)

Several previous systematic reviews of the literature have reported ultrasound performance in PsA,(1,10–12) however they did not compare enthesomal US to controls, and furthermore several additional studies have been published since.(3,13–18)

Studies have indicated that US was more sensitive than clinical examination for enthesitis.(1,19,20) However, the diagnostic value of US in PsA remains unclear. The specificity of US-defined enthesitis has recently been challenged.(6,11) Indeed, enthesitis was observed in patients without any inflammatory disease, with 34%-76% of US pathological findings at the enthesis level in healthy subjects and in patients with metabolic syndrome.(21–23) The specificity of US-enthesitis may also vary according to the control population. Presence of PD, which is a sign of active enthesitis, seems to be less frequent in healthy subjects.(21,22,24) Thus, presence of PD may be helpful to increase specificity.

All enthesitis may not be equivalent. It would be interesting to identify the enthesis sites of high specificity for PsA, and the underlying most specific lesions by US.(25) Because US is operator-dependent, reliability is a key issue and lower intra-reader and/or inter-reader reliability may play a role in the assessment of US sensitivity and specificity.(26)

The aim was to assess the performance of US and specifically of PD for the diagnosis of PsA through its specificity, sensitivity in comparison with diverse control populations, the reliability of US and to explore the most specific sites, through a systematic review with meta-analysis.

**Patients and methods**

We performed a systematic literature review (SLR) and a meta-analysis following the Cochrane guidelines.(27)

**Data sources and study selection**

The search was performed in the electronic database PubMed, for articles referenced between January 2010 and July 15, 2023. The date of 2010 was chosen because previous papers did not apply current standards to US.(28) The search was
conducted on the Ryyan platform, then full texts were read by one reviewer (NB),
with data extraction performed also by another author (CP) on a subset of articles.
The results were consistent across the 2 readers (95% agreement), on this subset of
articles. The search strategy was developed based on search terms aiming at
identifying studies including patients with PsA in which US was performed on
enthesis sites **(Supplementary Table S1)**.

Studies were selected if they included patients with confirmed PsA, who were >18
years of age and if they reported at least one information of interest on US-defined
enthesitis (please see below). Studies without PsA patients were excluded. A control
population was not mandatory. Publications could report trials or observational
studies; they had to be published in English. No selection based on quality was
applied.

General data extraction

Study characteristics and data were extracted using separate standardized forms for
each subject of interest. General data e.g. the type of study, type of PsA (use of
CASPAR Criteria, Classification criteria for Psoriatic Arthritis)(29), demographic
characteristics, body mass index (BMI), clinical PsA activity scores(30–32) and the
use of current conventional or biological disease-modifying antirheumatic drugs
(cDMARDs and bDMARDs) of the PsA patients and the controls (when applicable),
were extracted. The quality of the papers was not assessed due to the heterogeneity
of the studies.

Prevalence of US enthesitis

The frequency of US enthesitis, for PsA and control groups, was collected as the
number of patients with at least one US-enthesitis among all patients assessed.
The prevalence was assessed according to the OMERACT definition, which
corresponds to an hypoechoic and/or thickened insertion of the tendon close to the
bone (within 2 mm from the bony cortex) which exhibits PD signal if active and which
may show erosions and enthesophytes as a sign of structural damage.(7)

Use of an US score

US scores were collected in each PsA and control groups. The Glasgow
Ultrasound Enthesitis Scoring System (GUESS) assesses the quadriceps tendon on
the superior pole of the patella, the proximal patellar ligament, the distal patellar
ligament, the Achilles tendon, and plantar fascia, using only greyscale. The maximum
score that can be achieved by this index is 36 points.(33) The Madrid
Sonography Enthesitis Index (MASEI) includes the five previously described
entheses of the lower limbs and the insertion of the triceps on the olecranon and
assessed greyscale and PD; the maximum score is 136.(34) Other scores include the
Belgrade Ultrasound Enthesitis Score (BUSES)(35) and the D'Agostino score.(36)
The frequency of Achilles tendon enthesitis was collected according to the type of
lesion (hypo echogenicity, erosions, thickness, PD, calcification, bursitis and
enthesophytes).

Sensitivity and specificity of US for the diagnosis of PsA

The sensitivity and specificity of US for the diagnosis of PsA were collected at the
patient level and if available at the enthesis level. For the articles which did not
indicate them, sensitivity and specificity were calculated using the data provided in
the manuscript.
Sensitivity corresponds to the probability of having US-enthesitis for a PsA patient (or the probability of detecting an enthesitis in a PsA enthesis site, at the enthesis level).

Specificity corresponds to the probability of not having enthesitis for a person without PsA (or the probability of not detecting enthesitis in a non-PsA enthesis site, at the enthesis level).

All control populations were collected; analyses were performed for psychometric properties of US according to the control population.

Blinding of the sonographer to the diagnosis was also collected.

## Reliability

Intra-reader and inter-reader reliability, which measure the reproducibility of US, were collected.

## Statistical analysis

The number of studies and number of patients per study were extracted. Simple pooled percentages and pooled means were performed for patients' characteristics. Univariate random-effects meta-analysis was performed to calculate pooled percentages and pooled means in the PsA and control populations. Heterogeneity was assessed by I². A funnel plot was performed for specificity overall.

The pooled mean of enthesitis ultrasound scores (i.e., GUESS and MASEI) were compared between PsA and control patients using standardized mean difference (SMD), which expresses the distance between two group mean. A SMD<0.2 was considered as small, 0.2>SMD<0.8 as medium, and SMD>0.8 as large magnitude of the difference.

Sensitivity was calculated dividing the true positives by the sum of true positives and false negatives, while the specificity was calculated dividing the number of true negative by the sum of true negative and false positive. Specificity analysis was also stratified according to the control group and according to the patient- or enthesis-level.

Sub-group analyses and sensitivity analyses were performed as explained above.

The frequency of US enthesitis was collected according to the sites concerned and are reported for the five sites of the lower limb (Achilles tendon, quadriceps tendon, distal and proximal patellar ligament, plantar fascia). Due to a low quantity of data, we calculated simple pooled means or pooled percentages for the elementary lesions in the Achilles Tendon.

# Results

## Study characteristics

Of 350 abstracts initially identified, 76 were included (**Supplementary Figure S1**); 50 (65.8%) were cross-sectional studies, and 18 (23.7%) were longitudinal observational studies (**Table 1**). Most (44/65; 67.7%) were monocentric studies and most (51/76; 67.1%) were European studies.

Half of the studies (39/76; 51.3%) referred to the OMERACT definition, of which 14 (35.9%) referred to a 2mm cut-off from the bony cortex. Overall, 54/57 (94.7%) studies reported blinding of the sonographer for clinical examination/PsA diagnosis.

## Patient population
A total of 5,927 patients with PsA were analyzed (4-300 patients per study) compared to 3,423 controls (9-852 per study) who were mainly patients with psoriasis (2,020; 59.0%): **(Table 2)**.

The standard reference for the diagnosis of PsA was the CASPAR criteria, except in one study where the diagnosis was according to the rheumatologists (37) and in one study where the criteria were unclear.(38)

Patients with PsA had a weighted mean disease duration of 9.7 years, 51.0% were women, the weighted mean BMI was in the overweight category (26.6 kg/m²), 52.9% were taking csDMARDs and 33.3% bDMARDs (reported in 36/76 articles for both). Overall, 744/2,181 (34.1%) of PsA patients presented with at least 1 clinical enthesitis whatever the clinical score, where this information was available (i.e., in 21 articles).

## Prevalence of US enthesitis

Presence of at least one enthesitis was evidenced in 73.7% [95%CI, 56.6% - 90.9%] overall. This prevalence was higher using the OMERACT definition (80.0% [95%CI 64.2% - 95.7%]). In the control population (n=921), this prevalence was low, 12.6% [95%CI: 2.6% - 22.3%]. Among the control population, this frequency was higher in the psoriasis patients than in the healthy subjects **(Table 3)**.

The most frequently used US score was the MASEI in comparison with the GUESS. The GUESS score overall was significantly higher in PsA patients than in control patients (p=0.018). However, when subgroup analysis was performed, the differences between PsA and comparators were only significant for MASEI when comparators were psoriasis groups (p=0.001). **(Supplementary Table S2)**.

## Diagnostic performances of US

The assessment of performance for PsA diagnosis was reported in 5 articles, and was calculated for 8 others, with a total of 13 articles. **(Table 4)**.

Only 5 and 4 studies analysed total and Doppler performance of diagnosis in comparison with healthy subjects. Most of the studies analysed this data in comparison with psoriasis, rheumatoid arthritis, fibromyalgia, or lupus.

Overall US was quite specific of PsA diagnosis with 73.2% [95%CI: 59.3%-87.0%] specificity but with a lower sensitivity of 62.1% [95%CI: 47.9%-76.4%]. US specificity was higher when the control group was healthy people.

PD positivity increased the specificity with a pooled specificity of 97.9% [95%CI: 96.5%-99.5%] but with a very poor sensitivity of 14.7% [95%CI: 8.2%-21.2%]. Furthermore, PD specificity was excellent in all the control groups.

No bias in publication was noted **(Supplementary Figure S2)**.

## Enthesitis sites and elementary lesions

The most assessed sites were the Achilles tendon and quadriceps tendon in PsA patients, and the Achilles tendon in controls **(Table 5)**.

The most frequently involved site in PsA was the proximal patellar ligament (frequency of involvement in PsA patients, 57.8% [27.8%-87.7%] and the Achilles tendon, 49.3% [34.9%-63.6%]). In controls, it was the proximal patellar ligament (71.4%). Given the low number of control patients, it is difficult to conclude with certainty; however, the Achilles tendon appeared to be the most relevant site for diagnosis.
In the Achilles tendon, the specific lesions appeared to be erosions and PD, which were rare in the control group (8.6% vs 1.0%; 14.1% vs 2.9%, respectively). (Table 6) Moreover, no erosions or PD signals were found in healthy subjects. The most frequent lesion in PsA patients was enthesophytes (42.3%), but it was also the most frequent in the comparative group (29.9%), so it appeared to be the less specific.

## Reliability of US

Inter and intra-reliability was studied in 11 and 5 papers, respectively and was high: 98.5% [97.6%-99.4%] and 83.9% [72.5%-95.3%] respectively (Supplementary Table S3 and Supplementary Figure S3).

## Discussion

In this systematic literature review, ultrasound was found to be specific for the diagnosis of PsA, with a pooled specificity of 73.2% and with a reasonable though lower sensitivity of 62.1%; whereas PD was highly specific with a pooled specificity of 97.9% but with a very poor sensitivity of 14.7%. The sites most frequently involved in PsA were the proximal patellar ligament and the Achilles tendon, but the most specific site appeared to be the Achilles tendon, where the most specific lesions were erosions and presence of PD.

These findings on the performance of enthesis ultrasound are in line with previous SLRs: data are very variable across articles, with sensitivity tending to be low and specificity sometimes very high. (1,11,12) In addition, the present work has shown that specificity of US was increased by PD. An interesting finding, not previously reported, is that specificity of total US was excellent only when comparing PsA to healthy subjects. In psoriasis and other patients, total US specificity was lower, but was much improved by the use of PD: when a Doppler signal was present, the probability of a positive PsA diagnosis was high; in other terms, PD is unlikely to produce false positives. Thus, this parameter is interesting to discriminate PsA from differential diagnoses. Of note, the potential effect on the specificity of US and PD of DMARDs for psoriasis were not assessed here.(39)

However, the sensitivity of US was lower, and PD sensitivity was very poor. It appeared the low sensitivity was not attributable to the reliability, since both inter-reader and intra-reader reliability were high (98.5% and 83.9%), which is consistent with the literature.(40) US findings, and mostly PD findings, may be underestimated by cs/bDMARDs use which could perhaps explain the moderate sensitivity in the present meta-analysis where 52.9% and 33.3% of patients were treated with cs and bDMARDs respectively.(41,42) These findings show that presence of a PD signal cannot be relied upon in PsA screening.

The prevalence of enthesitis in the control group appeared lower than previously described in healthy subjects.(22-24) This difference could be explained by confounders such as body mass index, diabetes or physical activity.(24)

Most of the control groups were patients with psoriasis rather than other diagnoses. Psoriasis patients had more US enthesitis, perhaps due to sub-clinical PsA; the higher rate of US enthesitis evidenced in our work may reflect underdiagnosed PsA
in psoriasis patients.(43,44) Indeed, recent meta-analyses have indicated (under-diagnosed) PsA in 15-20% of patients with psoriasis.(45,46)

The non-significance of the MASEI score "overall" when comparing the control
groups to the PsA groups is explained by the heterogeneity of the results across
manuscripts that used MASEI. In this work, SMD was performed using random
effects because I² > 50%. However, applying non-random effect, the SMD would be
significant for the MASEI. This non-significance of the MASEI overall may also be
explained by the fact this analysis included all the control subgroups: significance is
found for the MASEI score when the analysis was performed in the psoriasis
subgroup.

Routine ultrasound scanning of each site can take time. One originality of our work is that we evaluated the discriminant sites of enthesitis in PsA. Knowing the prevalence of affected ultrasound sites in PsA patients versus controls is relevant in clinical practice; our results imply that the presence of proximal patellar ligament involvement is less discriminant than Achilles tendon involvement. Furthermore, our results concerning the specificity of the Achilles tendon, and those concerning specific lesions, are concordant with the recent study by Di Matteo et al.(47) An important finding of our study is that no erosion and no PD signal were found in the Achilles tendon sites of healthy subjects. It is interesting to note that some studies did evidence low rates of such abnormalities in the entheses of the lower limb of healthy subjects.(21,22,24)

These studies were not included in the SLR because they did not have an PsA
group; however, their findings put into context the findings from the present SLR.
The 3 studies of healthy people targeted specific groups such as overweight or
obese individuals (24) or people performing sports (22); the studies evidenced some
PD signal in a limited number of subjects, at the Achilles tendon insertion, without
erosions (21,22,24). We believe the low rates of PD positivity may be partly explained
by the population selection in these studies. However, they undermine the diagnostic
capacities of PD, which we demonstrated in our SLR. Thus, our findings on the
specificity of PD positivity may be helpful for clinicians and ultra-sonographers since
the presence of a Doppler signal or erosions in the Achilles tendon site could support
a diagnosis of PsA. However, the diagnosis of PsA should always be based on a
complete assessment and not rest solely on US.

The present meta-analysis did not allow any conclusions competed to clinical
examination. Indeed, only 2 of the 76 studies explored the performance of US in
comparison with clinical examination. Furthermore, no study assessed the
performance of PsA diagnosis by US in complement of the clinical examination.

This systematic review has some limitations. We used only one database, PubMed. However, this database regroups most clinical research papers, and our systematic review allowed us to analyze a high number of studies and of patients. We didn't perform a quality assessment of the studies; and data were extracted by a single reviewer. However, the verification on a subset of papers found high agreement between two data extractors. The findings should be treated with caution, as there were variations in results between articles. These variations could be explained by the heterogeneity of PsA and of other characteristics such as disease duration or BMI, which is associated with the presence of enthesitis.(48,49) The available data
were also reported in different ways: the locations, the scoring of the elementary
lesions and the definitions used differed from one study to another. For example, only
half the studies applied the OMERACT definition of enthesitis. Also, some papers
gave results at the patient level, while others gave them at the enthesis level. Finally,
the data were not always poolable, therefore the results do not all reflect the whole
population. A large part of the studies didn't have a case-control design, and the type
of controls was heterogeneous. The majority were psoriasis patients, whereas it
would have been relevant to compare US findings in patients with pain and
differential diagnoses such as other inflammatory rheumatic diseases or
fibromyalgia.(50) Finally, other types of imaging such as MRI were not assessed.
However, US is currently widely used in rheumatology clinical practice for its
accessibility, patient acceptability, instantaneous results and low cost.(51,52)

In conclusion, US-detected enthesitis is specific for the diagnosis of PsA when applied to healthy subjects. It is less specific in discriminating PsA from psoriasis patients or other differential diagnoses patients.

On the other hand, the presence of a Doppler signal and the presence of erosions in the Achilles tendon are highly specific for PsA diagnosis in patients with psoriasis or other diagnoses. Further assessment of these findings in more specific control populations such as people performing sports would be useful.
<table><caption>Table 1: Description of 76 studies reporting US-defined enthesitis in PsA</caption><thead><tr><th></th><th>All studies, N (%)</th><th>Studies using the OMERACT definition, N (%)</th><th>Studies not referring to the OMERACT definition, N (%)</th></tr></thead><tbody><tr><td>Total, N (%)</td><td>76 (100)</td><td>39 (51.3)</td><td>37 (49.7)</td></tr><tr><td>Study type, N (%)</td><td></td><td></td><td></td></tr><tr><td>Cross-sectional observational</td><td>50 (65.8)</td><td>27 (69.2)</td><td>23 (62.2)</td></tr><tr><td>Longitudinal observational</td><td>18 (23.7)</td><td>7 (17.9)</td><td>11 (28.2)</td></tr><tr><td>Other</td><td>8 (10.5)</td><td>5 (12.8)</td><td>3 (7.7)</td></tr><tr><td>Case-control design, N (%)</td><td>48 (100)</td><td>26 (66.7)</td><td>22 (59.5)</td></tr><tr><td>Monocentric studies, N (%)</td><td>44 (67.7)<sup>a</sup></td><td>23 (59.0)</td><td>21 (56.8)</td></tr><tr><td>Country of origin, N (%)</td><td></td><td></td><td></td></tr><tr><td>Europe only</td><td>51 (67.1)</td><td>26 (66.7)</td><td>25 (64.1)</td></tr><tr><td>Europe and other</td><td>3 (3.9)</td><td>1 (2.6)</td><td>2 (5.4)</td></tr><tr><td>Score used, n (%)</td><td></td><td></td><td></td></tr><tr><td>MASEI</td><td>23 (71.9)<sup>a,b</sup></td><td>8 (20.5)</td><td>14 (35.9)</td></tr><tr><td>GUESS</td><td>9 (28.1)<sup>a,b</sup></td><td>3 (7.7)</td><td>6 (16.2)</td></tr></tbody></table>

From the other study types: 2 were random control trials, 4 were retrospective and 2 were reliability studies.

OMERACT: Outcome Measures in Rheumatology; GUESS: Glasgow

Ultrasound Enthesitis Scoring System; MASEI: Madrid Sonography Enthesitis Index

<footnote>a Percentage of available data. b Two articles reported both MASEI and GUESS</footnote>
<table><caption>Table 2: Description of the patients analyzed for enthesitis by ultrasound</caption><thead><tr><th></th><th>PsA patients<br>N=5,927</th><th>Psoriasis patients<br>N=2,020</th><th>Healthy subjects<br>N=668</th><th>Other patients<sup>b</sup><br>N=735</th></tr></thead><tbody><tr><td>Articles, N</td><td>75</td><td>20</td><td>16</td><td>18</td></tr><tr><td>Age, years, weighted mean<br>(min-max of means)</td><td>49.6 (37.8 - 61.0) [66]</td><td>44.0 (38.2 - 59.0) [16]</td><td>45.8 (22.0 - 61.0) [10]</td><td>48.00 (24.0 - 69.5) [14]</td></tr><tr><td>Disease duration, years,<br>weighted mean (min-max)</td><td>9.7 (0.6 - 53.4) [55]</td><td>NA</td><td>NA</td><td>NA</td></tr><tr><td>Female, total (%)</td><td>2400 (51.0)<sup>a</sup> [55]</td><td>569 (46.0)<sup>a</sup> [15]</td><td>239 (49.8)<sup>a</sup> [11]</td><td>370 (63.2)<sup>a</sup> [14]</td></tr><tr><td>BMI, weighted mean (min-max)<br>(kg/m<sup>2</sup>)</td><td>26.6 (21.8-30.9)<sup>a</sup> [31]</td><td>25.424 (23.8-28.6)<sup>a</sup> [7]</td><td>24.8 (23.1-26.7)<sup>a</sup> [6]</td><td>25.9 (21.7-28.1)<sup>a</sup> [6]</td></tr><tr><td>CRP, mg/l, weighted mean (min-max)</td><td>7.7 (0.4 - 24.4) [32]</td><td>4.6 (1.5-8.2) [8]</td><td>NA</td><td>10.0 (1.4-20.0) [8]</td></tr><tr><td>Current csDMARDs intake,<br>pooled %, min-max</td><td>52.9% (0 - 100%) [36]</td><td>25.3% (0% - 86.0%) [9]</td><td>NA</td><td>39.3% (7.0% - 53.3%) [2]</td></tr><tr><td>Current bDMARDs intake,<br>pooled %, (min-max)</td><td>33.3% (0-78.0%) [36]</td><td>45.0% (0% - 61.6%) [10]</td><td>NA</td><td>42.2% (20.0%-50.6%) [2]</td></tr></tbody></table>

One study of the 75 studies analysed is not showed on this table(26) because it was a reliability study with only three patients studied (1 PsA and 2 SpA). The [number] in each column represents the number of studies reporting this characteristic (of 75 studies). <sup>a</sup>Percentage of available data. <sup>b</sup>For the other group of patients, 6 studies had rheumatoid arthritis groups, 4 axial spondylarthritis groups, 3 fibromyalgia groups, 1 lupus group, 1 hand osteoarthritis group and 1 psori or other osteoarthritis group.

PsA: Psoriatic arthritis; CRP: c-reactive protein; BMI: Body Mass Index; cDMARDs: conventional disease-modifying antirheumatic drugs; bDMARDs: biological disease-modifying antirheumatic drugs; NA: non available.
<table><caption>**Table 3: Frequency of US enthesitis according to the definitions and the groups**</caption><thead><tr><th></th><th>Number of studies, N</th><th>Number patients, N</th><th>Pooled frequency (95%CI)</th><th>Heterogeneity (I²)</th><th>p-value I²</th></tr></thead><tbody><tr><td colspan="6"><strong>PsA patients</strong></td></tr><tr><td>Patients with at least one enthesitis according to the OMERACT definition</td><td>12</td><td>970</td><td>80.0% (64.2% - 95.7%)</td><td>98.8%</td><td>&lt;0.0001</td></tr><tr><td>Patients with at least one enthesitis according to another definition</td><td>2</td><td>415</td><td>60.2% (-2.9% - 123.2%)</td><td>98.0%</td><td>&lt;0.001</td></tr><tr><td colspan="6"><strong>Comparative patients</strong></td></tr><tr><td>Patients with at least one enthesitis according to the OMERACT definition</td><td>9</td><td>921</td><td>12.6% (2.9% to 22.3%)</td><td>60.3%</td><td>0.003</td></tr><tr><td>- <em>Psoriasis</em></td><td>3</td><td>524</td><td>16.1% (9.5% to 22.7%)</td><td>0.0%</td><td>0.950</td></tr><tr><td>- <em>Healthy</em></td><td>2</td><td>90</td><td>1.3% (-1.9% to 4.5%)</td><td>0.0%</td><td>0.891</td></tr><tr><td>- <em>Other</em></td><td>4</td><td>307</td><td>35.8% (-1.2% to 72.8%)</td><td>37.1%</td><td>0.255</td></tr><tr><td>Patients with at least one enthesitis according to another definition</td><td>2</td><td>102</td><td>87.1% (55.9% to 118.4%)</td><td>0.0%</td><td>0.708</td></tr><tr><td>- <em>Psoriasis</em></td><td>1</td><td>51</td><td>90.0%</td><td>-</td><td>-</td></tr><tr><td>- <em>Other</em></td><td>1</td><td>51</td><td>74.6%</td><td>-</td><td>-</td></tr></tbody></table>

PsA: Psoriatic Arthritis; OMERACT: Outcome Measures in Rheumatology; CI: confidence interval; N: Number
<table><caption>**Table 4: Specificity and sensitivity of US and specifically of PD for the diagnosis of PsA**</caption><thead><tr><th></th><th>Number of studies, N</th><th>Number of patients, N</th><th>PsA/N control</th><th>Pooled result (95%CI)</th><th>Heterogeneity (I²)</th><th>p-value I²</th></tr></thead><tbody><tr><td colspan="7"><strong>Total US</strong></td></tr><tr><td><strong>Sensitivity</strong></td><td>13</td><td>1299/1384</td><td></td><td>62.1% (47.9% to 76.4%)</td><td>92.8%</td><td>&lt;0.001</td></tr><tr><td>-Patient-level</td><td>11</td><td>1059/1206</td><td></td><td>81.1% (70.5% to 91.8%)</td><td>33.6%</td><td>0.263</td></tr><tr><td>-Enthesis-level</td><td>4</td><td>240/178<sup>a</sup></td><td></td><td>44.7% (22.0% to 67.5%)</td><td>97.7%</td><td>&lt;0.001</td></tr><tr><td><strong>Specificity</strong></td><td>13</td><td>1299/1384</td><td></td><td>73.2% (59.3% to 87.0%)</td><td>98.7%</td><td>&lt;0.001</td></tr><tr><td>-Patient-level</td><td>11</td><td>1059/1206</td><td></td><td>68.8% (48.5% to 89.2%)</td><td>99.2%</td><td>&lt;0.001</td></tr><tr><td>-Enthesis-level</td><td>4</td><td>240/178<sup>a</sup></td><td></td><td>80.0% (70.5% to 89.5%)</td><td>90.1%</td><td>&lt;0.001</td></tr><tr><td>Among comparators:</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>- Psoriasis</td><td>4</td><td>307/616</td><td></td><td>59.8% (10.6% to 108.9%)</td><td>89.3%</td><td>&lt;0.001</td></tr><tr><td>- Healthy</td><td>5</td><td>363/285</td><td></td><td>91.8% (85.1% to 98.6%)</td><td>72.1%</td><td>&lt;0.001</td></tr><tr><td>- Other</td><td>7</td><td>489/483</td><td></td><td>69.8% (52.1% to 87.4%)</td><td>97.1%</td><td>&lt;0.001</td></tr><tr><td colspan="7"><strong>PD</strong></td></tr><tr><td><strong>Sensitivity</strong></td><td>13</td><td>1673/2162</td><td></td><td>14.7% (8.2% to 21.2%)</td><td>98.3%</td><td>&lt;0.001</td></tr><tr><td>-Patient-level</td><td>11</td><td>1297/1623</td><td></td><td>30.9% (13.3% to 48.6%)</td><td>88.0%</td><td>&lt;0.001</td></tr><tr><td>-Enthesis-level</td><td>4</td><td>376/539<sup>b</sup></td><td></td><td>11.2% (7.4% to 14.9%)</td><td>89.9%</td><td>&lt;0.001</td></tr><tr><td><strong>Specificity</strong></td><td>13</td><td>1673/2162</td><td></td><td>97.9% (96.5% to 99.5%)</td><td>99.9%</td><td>&lt;0.001</td></tr><tr><td>-Patient-level</td><td>11</td><td>1297/1623</td><td></td><td>99.9% (99.9% to 100.0%)</td><td>0.0%</td><td>0.009</td></tr><tr><td>-Enthesis-level</td><td>4</td><td>376/539<sup>b</sup></td><td></td><td>97.3% (95.3% to 99.2%)</td><td>99.0%</td><td>&lt;0.001</td></tr><tr><td>Among comparators:</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>- Psoriasis</td><td>6</td><td>749/1551</td><td></td><td>96.6% (92.9% to 100.2%)</td><td>71.9%</td><td>&lt;0.001</td></tr><tr><td>- Healthy</td><td>4</td><td>411/246</td><td></td><td>99.2% (98.0% to 100.4%)</td><td>99.1%</td><td>&lt;0.001</td></tr><tr><td>- Others</td><td>7</td><td>513/365</td><td></td><td>96.8% (93.8% to 99.9%)</td><td>98.9%</td><td>&lt;0.001</td></tr></tbody></table>

US: Ultrasonography; PD: Power Doppler

Some studies were used several times, since they used different control groups or different levels: each control groups were compared separately with the PsA group. <sup>a</sup>2,236/1,620 enthesitis <sup>b</sup>3,851/3,265 enthesis
<table><caption>**Table 5: Prevalence of involved enthesis sites in PsA and control patients**</caption><thead><tr><th></th><th>Number of studies, N</th><th>Number of patients, N</th><th>Pooled percentage (95%CI)</th><th>Heterogeneity (I²)</th><th>p-value I²</th></tr></thead><tbody><tr><td colspan="6"><strong>PsA patients</strong></td></tr><tr><td>Achilles tendon</td><td>9</td><td>703</td><td>49.3% (34.9% to 63.6%)</td><td>0.0%</td><td>0.999</td></tr><tr><td>Proximal patella</td><td>4</td><td>239</td><td>57.8% (27.8% to 87.7%)</td><td>5.5%</td><td>0.621</td></tr><tr><td>Distal patella</td><td>5</td><td>260</td><td>47.4% (19.6% to 75.2%)</td><td>0.0%</td><td>0.907</td></tr><tr><td>Quadriceps tendon</td><td>7</td><td>650</td><td>47.8% (33.7% to 61.9%)</td><td>0.0%</td><td>0.931</td></tr><tr><td>Plantar fascia</td><td>5</td><td>368</td><td>18.0% (4.1% to 31.9%)</td><td>0.0%</td><td>0.998</td></tr><tr><td colspan="6"><strong>Comparative patients</strong></td></tr><tr><td>Achilles tendon</td><td>5</td><td>123</td><td>29.1% (-36.9% to 95.1%)</td><td>0.0%</td><td>0.996</td></tr><tr><td>- Psoriasis</td><td>3</td><td>63</td><td>26.0% (-64.8% to 116.9%)</td><td>0.0%</td><td>0.920</td></tr><tr><td>- Healthy</td><td>1</td><td>20</td><td>27.3%</td><td>-</td><td>-</td></tr><tr><td>- Other</td><td>1</td><td>40</td><td>34.2%</td><td>-</td><td>-</td></tr><tr><td>Proximal patella (control groups: psoriasis)</td><td>2</td><td>42</td><td>71.4% (-47.7% to 190.4%)</td><td>0.0%</td><td>0.878</td></tr><tr><td>Distal patella (control groups: psoriasis)</td><td>2</td><td>42</td><td>32.6% (-100.2% to 165.3%)</td><td>0.0%</td><td>0.957</td></tr><tr><td>Quadriceps tendon (control groups: psoriasis)</td><td>2</td><td>42</td><td>30.3% (-97.6% to 158.2%)</td><td>0.0%</td><td>0.970</td></tr><tr><td>Plantar fascia (control groups: psoriasis)</td><td>2</td><td>42</td><td>15.0% (-62.5% to 92.5%)</td><td>0.0%</td><td>0.947</td></tr></tbody></table>

PsA: psoriatic arthritis; CI: confidence interval, N: Number
<table><caption>**Table 6: Prevalence of lesions in the Achilles tendon in PsA patients and control groups**</caption><thead><tr><th></th><th>Number of articles, N</th><th>Number of PsA patients, N</th><th>Number of Comparative patients, N</th><th>Results for PsA, pooled % (range) or pooled mean mm (range)</th><th>Results for comparative, pooled % (range) or pooled mean mm (range)</th></tr></thead><tbody><tr><td>Hypo-echogenicity, pooled % (range)</td><td>2</td><td>244</td><td>102</td><td>28.3 (27.6; 28.6)</td><td>12.7 (7.8; 17.6)</td></tr><tr><td>Erosions, pooled % (range)</td><td>7</td><td>594</td><td>206</td><td>8.6 (2.0-14.6)</td><td>1.0 (0.0-2.0)</td></tr><tr><td>Thickness, pooled mean mm (range)</td><td>6</td><td>441</td><td>230</td><td>4.6 (3.5-5)</td><td>4.1 (3-4.7)</td></tr><tr><td>Bursitis, pooled % (range)</td><td>6</td><td>490</td><td>206</td><td>10.8 (3.2-28.5)</td><td>6.3 (0.0-9.8)</td></tr><tr><td>Enthesophytes, pooled % (range)</td><td>5</td><td>449</td><td>206</td><td>41.2 (22.7-61.9)</td><td>26.7 (5.0-52.9)</td></tr><tr><td>Calcifications, pooled % (range)</td><td>2</td><td>51</td><td>60</td><td>42.3 (28.6-61.9)</td><td>29.9 (28.9;31.8)</td></tr><tr><td>PD signal, pooled % (range)</td><td>6</td><td>440</td><td>171</td><td>14.1 (2.0-24.4)</td><td>2.9 (0-5.0)</td></tr></tbody></table>

PsA: Psoriatic Arthritis; PD: Power Doppler; N: Number. Given the low number of studies, naïve pooling was performed.
## References

1. Zabotti A, Bandinelli F, Batticciotto A, Scirè CA, Iagnocco A, Sakellariou G, et al. Musculoskeletal ultrasonography for psoriatic arthritis and psoriasis patients: a systematic literature review. Rheumatology. 1 sept 2017;56(9):1518-32.

2. Draghi F, Ferrozzi G, Ballerini D, Bortolotto C. Psoriatic arthritis: Ultrasound peculiarities with particular emphasis on enthesitis. J Clin Ultrasound. mai 2022;50(4):556-60.

3. Abdelghani KB, Boussaa H, Miladi S, Zakraoui L, Fazaa A, Laatar A. Value of Hands Ultrasonography in the Differential Diagnosis Between Psoriatic Arthritis and Rheumatoid Arthritis. J Ultrasound Med. sept 2023;42(9):1987-95.

4. Hamitouche F, Lopez-Medina C, Gossec L, Perrot S, Dougados M, Moltó A. Evaluation of the agreement between the ACR 1990 fibromyalgia tender points and an enthesitis score in patients with axial spondyloarthritis. Rheumatol Oxf Engl. 1 août 2023;62(8):2757-64.

5. Forien M, Ebstein E, Léger B, Benattar L, Dieudé P, Ottaviani S. Ankle retinacula abnormalities as features of psoriatic arthritis: An ultrasound study. Joint Bone Spine. janv 2024;91(1):105649.

6. Smerilli G, Di Matteo A, Cipolletta E, Grassi W, Filippucci E. Enthesitis in Psoriatic Arthritis, the Sonographic Perspective. Curr Rheumatol Rep. sept 2021;23(9):75.

7. Balint PV, Terslev L, Aegerter P, Bruyn GAW, Chary-Valckenaere I, Gandjbakhch F, et al. Reliability of a consensus-based ultrasound definition and scoring for enthesitis in spondyloarthritis and psoriatic arthritis: an OMERACT US initiative. Ann Rheum Dis. déc 2018;77(12):1730-5.

8. Kaeley GS, Roth J. Imaging and rheumatic and musculoskeletal diseases. Best Pract Res Clin Rheumatol. déc 2020;34(6):101642.

9. Mandl P, Navarro-Compán V, Terslev L, Aegerter P, Van Der Heijde D, D'Agostino MA, et al. EULAR recommendations for the use of imaging in the diagnosis and management of spondyloarthritis in clinical practice. Ann Rheum Dis. juill 2015;74(7):1327-39.

10. Elalouf O, Bakirci Ureyen S, Touma Z, Anderson M, Kaeley GS, Aydin SZ, et al. Psoriatic Arthritis Sonographic Enthesitis Instruments: A Systematic Review of the Literature. J Rheumatol. janv 2019;46(1):43-56.

11. Sakellariou G, Scirè CA, Adinolfi A, Batticciotto A, Bortoluzzi A, Delle Sedie A, et al. Differential Diagnosis of Inflammatory Arthropathies by Musculoskeletal Ultrasonography: A Systematic Literature Review. Front Med. 7 mai 2020;7:141.

12. Patience A, Steultjens MP, Hendry GJ. Ultrasound features of Achilles enthesitis in psoriatic arthritis: a systematic review. Rheumatol Adv Pract. 5 nov 2021;5(Supplement_2):ii19-34.

13. Furer V, Wollman J, Levartovsky D, Aloush V, Elalouf O, Sarbagil-Maman H, et al. Sex-Based Differences in Sonographic and Clinical Findings Among Patients With Psoriatic Arthritis. J Rheumatol. févr 2023;50(2):197-203.

14. Perrotta FM, Ronga M, Scriffignano S, Lubrano E. Ultrasonographic Evaluation of Entheseal Fibrocartilage in Patients with Psoriatic Arthritis, Athletes and Healthy Controls: A Comparison Study. Diagnostics. 17 avr 2023;13(8):1446.

15. Wang Y, Xiao Y, Li F, Gu Y, Yang M, Zhang L, et al. The Clinical Characteristics of Psoriatic Arthritis: A Cross-Sectional Study Based on the Psoriatic Arthritis Cohort of West China Hospital. Rheumatol Ther. juin 2023;10(3):775-84.

16. Bhoi AK, Grover C, Singal A, Tandon A. Enthesopathy in patients with nail psoriasis – a cross-sectional evaluation of clinical, onychoscopic and ultrasonographic features. Indian J Dermatol Venereol Leprol. 3 mai 2023;89:854-61.
17. Chen ZT, Chen RF, Li XL, Wang Q, Ren WW, Shan DD, et al. The role of ultrasound in screening subclinical psoriatic arthritis in patients with moderate to severe psoriasis. Eur Radiol. 28 févr 2023;33(6):3943-53.

18. Balulu G, Furer V, Wollman J, Levartovsky D, Aloush V, Elalouf O, et al. The association between sonographic enthesitis with sonographic synovitis and tenosynovitis in psoriatic arthritis patients. Rheumatology. 4 janv 2024;63(1):190-7.

19. Freeston JE, Coates LC, Helliwell PS, Hensor EMA, Wakefield RJ, Emery P, et al. Is there subclinical enthesitis in early psoriatic arthritis? A clinical comparison with power doppler ultrasound. Arthritis Care Res. oct 2012;64(10):1617-21.

20. Norden A, Oulee A, Ivanic M, Javadi SS, Han G, Wu JJ. The use of ultrasound to detect enthesitis as a potential guide for intervention in patients with psoriasis at risk of psoriatic arthritis: a systematic review. Int J Dermatol. août 2023;62(8):973-9.

21. Guldberg-Møller J, Terslev L, Nielsen SM, Koenig MJ, Torp-Pedersen ST, Torp-Pedersen A, et al. Ultrasound pathology of the entheses in an age and gender stratified sample of healthy adult subjects: a prospective cross-sectional frequency study. Clin Exp Rheumatol. 2019;

22. Di Matteo A, Filippucci E, Cipolletta E, Martire V, Jesus D, Musca A, et al. How normal is the enthesis by ultrasound in healthy subjects? Clin Exp Rheumatol. 2020;38(3):472-8.

23. Falsetti P, Conticini E, Baldi C, Acciai C, Frediani B. High prevalence of ultrasound-defined enthesitis in patients with metabolic syndrome. Comment on: How normal is the enthesis by ultrasound in healthy subjects? Di Matteo et al. Clin Exp Rheumatol. 2021;39(2):435-6.

24. Bakirci S, Solmaz D, Stephenson W, Eder L, Roth J, Aydin SZ. Entheseal Changes in Response to Age, Body Mass Index, and Physical Activity: An Ultrasound Study in Healthy People. J Rheumatol. 1 juill 2020;47(7):968-72.

25. Tom S, Zhong Y, Cook R, Aydin SZ, Kaeley G, Eder L. Development of a Preliminary Ultrasonographic Enthesitis Score in Psoriatic Arthritis — GRAPPA Ultrasound Working Group. J Rheumatol. avr 2019;46(4):384-90.

26. Moya Alvarado P, De Agustín De Oro JJ, Aparicio Espinar M, Armengol Pérez E, Busquets Pérez N, Carmona L, et al. Interobserver reliability of Masei index validation by a multicenter collaborative group of rheumatologists. Rheumatol Int. mars 2022;42(3):441-8.

27. Cochrane Guidelines for Meta Analyses [Internet]. [cité 8 avr 2024]. Disponible sur: https://training.cochrane.org/handbook/current/chapter-10

28. Kaeley GS. Review of the Use of Ultrasound for the Diagnosis and Monitoring of Enthesitis in Psoriatic Arthritis. Curr Rheumatol Rep. août 2011;13(4):338-45.

29. Taylor W, Gladman D, Helliwell P, Marchesoni A, Mease P, Mielants H, et al. Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthritis Rheum. août 2006;54(8):2665-73.

30. Gladman DD, Cook RJ, Schentag C, Feletar M, Inman RI, Hitchon C, et al. The clinical assessment of patients with psoriatic arthritis: results of a reliability study of the spondyloarthritis research consortium of Canada. J Rheumatol. juin 2004;31(6):1126-31.

31. Healy PJ, Helliwell PS. Measuring clinical enthesitis in psoriatic arthritis: assessment of existing measures and development of an instrument specific to psoriatic arthritis. Arthritis Rheum. 15 mai 2008;59(5):686-91.

32. Heuft-Dorenbosch L, Spoorenberg A, van Tubergen A, Landewé R, van ver Tempel H, Mielants H, et al. Assessment of enthesitis in ankylosing spondylitis. Ann Rheum Dis. févr 2003;62(2):127-32.

33. Balint PV. Ultrasonography of entheseal insertions in the lower limb in spondyloarthropathy. Ann Rheum Dis. 1 oct 2002;61(10):905-10.
34. De Miguel E, Cobo T, Muñoz-Fernández S, Naredo E, Usón J, Acebes JC, et al. Validity of enthesis ultrasound assessment in spondyloarthropathy. Ann Rheum Dis. févr 2009;68(2):169-74.

35. Milutinovic S, Radunovic G, Veljkovic K, Zlatanovic M, Zlatkovic Svenda M, Perovic Radak M, et al. Development of ultrasound enthesitis score to identify patients with enthesitis having spondyloarthritis: prospective, double-blinded, controlled study. Clin Exp Rheumatol. 2015;33(6):812-7.

36. D'Agostino M, Said- Nahal R, Hacquard- Bouder C, Brasseur J, Dougados M, Breban M. Assessment of peripheral enthesitis in the spondylarthropathies by ultrasonography combined with power Doppler: A cross- sectional study. Arthritis Rheum. févr 2003;48(2):523-33.

37. Ayan G, Tinazzi I, Bakirci S, Gazel U, Solmaz D, Kalyoncu U, et al. Disease activity at the entheses and joints are correlated in psoriatic arthritis when explored with ultrasound. Clin Exp Rheumatol. 28 janv 2022;40(1):44-8.

38. Wervers K, Vis M, Rasappu N, Van Der Ven M, Tchetverikov I, Kok M, et al. Modification of a sonographic enthesitis score to differentiate between psoriatic arthritis and young healthy volunteers. Scand J Rheumatol. 4 juill 2018;47(4):291-4.

39. Molina Collada J, Macía-Villa C, Plasencia-Rodríguez C, Álvaro-Gracia J, De Miguel E. Ultrasound Doppler enthesitis shows sensitivity to change after biological therapy in spondyloarthritis and psoriatic arthritis patients. Scand J Rheumatol. 4 mai 2022;51(3):196-204.

40. Naredo E, D'Agostino MA, Terslev L, Pineda C, Miguel MI, Blasi J, et al. Validation and incorporation of digital entheses into a preliminary Global OMERACT UltrasoundDActylitis Score (GLOUDAS) in psoriatic arthritis. Ann Rheum Dis. 4 avr 2024;ard-2023-225278.

41. Smerilli G, Cipolletta E, Di Matteo A, Di Carlo M, Moscioni E, Francioso F, et al. «Double target» ultrasound monitoring of biologic therapy in psoriatic arthritis. Clin Exp Rheumatol. mars 2024;42(3):626-32.

42. Elliott A, Wright G, Pendleton A, Rooney M. Effects of TNF-α inhibition versus secukinumab on active ultrasound-confirmed enthesitis in psoriatic arthritis. Ther Adv Musculoskelet Dis. 2023;15:1759720X231179524.

43. Gottlieb AB, Merola JF. A clinical perspective on risk factors and signs of subclinical and early psoriatic arthritis among patients with psoriasis. J Dermatol Treat. juin 2022;33(4):1907-15.

44. Naredo E, Möller I, de Miguel E, Batlle-Gualda E, Acebes C, Brito E, et al. High prevalence of ultrasonographic synovitis and enthesopathy in patients with psoriasis without psoriatic arthritis: a prospective case-control study. Rheumatol Oxf Engl. oct 2011;50(10):1838-48.

45. Alinaghi F, Calov M, Kristensen LE, Gladman DD, Coates LC, Jullien D, et al. Prevalence of psoriatic arthritis in patients with psoriasis: A systematic review and meta-analysis of observational and clinical studies. J Am Acad Dermatol. janv 2019;80(1):251-265.e19.

46. Villani AP, Rouzaud M, Sevrain M, Barnetche T, Paul C, Richard MA, et al. Prevalence of undiagnosed psoriatic arthritis among psoriasis patients: Systematic review and meta-analysis. J Am Acad Dermatol. août 2015;73(2):242-8.

47. Di Matteo A, Smerilli G, Di Donato S, Liu AR, Becciolini A, Camarda F, et al. Power Doppler signal at the enthesis and bone erosions are the most discriminative OMERACT ultrasound lesions for SpA: results from the DEUS (Defining Enthesitis on Ultrasound in Spondyloarthritis) multicentre study. Ann Rheum Dis. 5 mars 2024;ard-2023-225443.

48. Puche-Larrubia MÁ, Ladehesa-Pineda L, López-Montilla MD, Barbarroja N,
Escudero-Contreras A, Vazquez-Mellado J, et al. Differences between early vs. late-onset of psoriatic arthritis: Data from the RESPONDIA and REGISPONSER registries. Joint Bone Spine. juill 2023;90(4):105563.

49. Leung YY, Eder L, Orbai AM, Coates LC, de Wit M, Smolen JS, et al. Association between obesity and likelihood of remission or low disease activity status in psoriatic arthritis applying index-based and patient-based definitions of remission: a cross-sectional study. RMD Open. sept 2023;9(3):e003157.

50. Fitzgerald GE, Maguire S, Lopez-Medina C, Dougados M, O'Shea FD, Haroon N. Tender to touch-Prevalence and impact of concomitant fibromyalgia and enthesitis in spondyloarthritis: An ancillary analysis of the ASAS PerSpA study. Joint Bone Spine. nov 2022;89(6):105420.

51. Serrano-Warleta M, Palomeque-Vargas A, Manzo R, Blanco-Cáceres B, Vazquez-Díaz M, Guillen-Astete C. Usefulness of ultrasound in clinical decision-making in rheumatology clinical practice: A single-center longitudinal study. Reumatol Clínica Engl Ed. mars 2024;20(3):147-9.

52. Mandl P, Baranauskaite A, Damjanov N, Hojnik M, Kurucz R, Nagy O, et al. Musculoskeletal ultrasonography in routine rheumatology practice: data from Central and Eastern European countries. Rheumatol Int. juin 2016;36(6):845-54.
<table><caption>**Supplementary Table S1: Additional information on methods used**</caption><tr><td>Date of search</td><td>January 2010 – July 2023</td></tr><tr><td>Key words used</td><td>('Enthesopathy'[Mesh] OR Enthesopath* OR Enthesitis OR entheses OR enthesis OR entheséal OR enthesophyt* OR enthesi*) AND ('Ultrasonography'[Mesh] OR 'Ultrasonography' OR ultrasonograph* OR US OR Ultrasound* OR 'Ultrasound imaging' OR ultrasonographically OR sonograph* OR 'Ultrasonography, Doppler'[Mesh] OR 'power Doppler' OR doppler) AND ("psoriatic arthritis" OR "arthritis, psoriatic"[MeSH Terms] OR PsA OR "psoriatic arthropath*")</td></tr></table>
<figure><img src="image_3.png" /><figcaption>**<u>Supplementary Figure S1:</u>** Flow Chart, systematic review of US enthesitis in PsA</figcaption></figure>
**Supplementary Table S2: Mean US scores according to the groups:**

<table><thead><tr><th></th><th>Number of studies</th><th>N patients PsA</th><th>Pooled mean PsA (95%CI)</th><th>N patients comparator</th><th>Pooled mean comparator (95%CI)</th><th>SMD (95%)</th><th>p-value SMD</th><th>Heterogeneity (I<sup>2</sup>)</th><th>p-value I<sup>2</sup></th></tr></thead><tbody><tr><td>GUESS overall</td><td>6</td><td>454</td><td>11.3 (4.3 to 18.2)</td><td>264</td><td>4.8 (1.9 to 7.7)</td><td>0.8 (0.1 to 1.5)</td><td>0.018</td><td>94.4%</td><td>&lt;0.001</td></tr><tr><td>PsA vs Psoriasis</td><td>3</td><td>376</td><td>12.7 (2.7 to 228)</td><td>241</td><td>6.2 (1.3 to 11.0)</td><td>0.8 (-0.2 to 1.7)</td><td>0.112</td><td>96.3%</td><td>&lt;0.001</td></tr><tr><td>MASEI overall</td><td>9</td><td>323</td><td>14.8 (10.3 to 19.4)</td><td>329</td><td>11.3 (4.5 to 18.0)</td><td>0.3 (-0.3 to 0.9)</td><td>0.351</td><td>97.8%</td><td>&lt;0.001</td></tr><tr><td>PsA vs Psoriasis</td><td>3</td><td>106</td><td>8.7 (4.2 to 13.2)</td><td>97</td><td>5.1 (4.1 to 6.2)</td><td>0.5 (0.2 to 0.8)</td><td>0.001</td><td>0%</td><td>0.609</td></tr><tr><td>PsA vs healthy</td><td>4</td><td>264</td><td>14.0 (11.7 to 16.3)</td><td>190</td><td>7.2 (2.2 to 12.1)</td><td>0.7 (-0.1 to 1.4)</td><td>0.059</td><td>92.2%</td><td>&lt;0.001</td></tr><tr><td>PsA vs other</td><td>2</td><td>47</td><td>29.1 (25.5 to 32.7)</td><td>42</td><td>28.9 (25.8 to 31.9)</td><td>0.0 (-0.4 to 0.4)</td><td>0.967</td><td>0%</td><td>0.390</td></tr></tbody></table>

PsA: Psoriatic arthritis; vs: versus; N: Number; GUESS: Glasgow Ultrasound Enthesitis Scoring System; MASEI: Madrid Sonography Enthesitis Index; SMD: standardized mean difference; CI: confidence interval
<figure><img src="image_4.png" /><figcaption>**<u>Supplementary Figure S2:</u>** Funnel plot of total US and US doppler sensitivity and specificity</figcaption></figure>

A. Standard error according to the effect size for sensitivity of Ultrasound (US). B. Standard error according to the effect size for specificity of US. C. Standard error according to the Effect Size for sensitivity of Power Doppler (PD). D. Standard error according to the Effect Size for specificity of PD.
<table><caption>**Supplementary Table S3: Inter and intra-reader reliability:**</caption><thead><tr><th></th><th>Number of studies</th><th>Number of patients</th><th>Pooled percentage (95%CI)</th><th>Percentage to</th><th>Heterogeneity (I²)</th><th>p-value I²</th></tr></thead><tbody><tr><td>Inter-reader reliability</td><td>11</td><td>845</td><td>98.5% (97.6% to 99.4%)</td><td></td><td>0.0%</td><td>0.897</td></tr><tr><td>Intra-reader reliability</td><td>5</td><td>380</td><td>83.9% (72.5% to 95.3%)</td><td></td><td>0.0%</td><td>0.794</td></tr></tbody></table>

<figure><img src="image_5.png" /><figcaption>**Supplementary Figure S3: Funnel Plot of intra and inter-reader reliability**</figcaption></figure>

A. Standard error according to the effect size for inter-reader reliability of the ultrasound (US). B. Standard error according to the effect size for intra-reader reliability of the US.