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

HAL
open science

# Capillary CRP in primary care in France: an observational study

Amélie Richard, Céline Lambert, Pierre Bernard, Hélène Vaillant-Roussel, Catherine Laporte

► To cite this version:

Amélie Richard, Céline Lambert, Pierre Bernard, Hélène Vaillant-Roussel, Catherine Laporte. Capillary CRP in primary care in France: an observational study. BMC Primary Care, 2025, 26 (1), pp.269. 10.1186/s12875-025-02924-9. hal-05240105

HAL Id: hal-05240105

https://hal.science/hal-05240105v1

Submitted on 4 Sep 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
RESEARCH

Open Access

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

Check for
updates

# Capillary CRP in primary care in France: an observational study

Amélie Richard¹,<fnref n="2" />,<fnref n="3" />*, Céline Lambert<fnref n="4" />, Pierre Bernard¹, Hélène Vaillant-Roussel¹,<fnref n="2" />,<fnref n="4" /> and Catherine Laporte¹,<fnref n="5" />

**Abstract**

**Background** Antibiotic resistance causes 700,000 deaths annually worldwide. In France, diagnostic uncertainty in consultations leads to inappropriate prescribing of antibiotics, which increases antibiotic resistance. Capillary C-reactive protein (CRP) machines can provide a CRP measurement in primary care in two minutes and can help general practitioners in their prescribing decisions. The aim of this study was to evaluate the use of capillary CRP in primary care, as well as its impact on the following: the main reasons for consultation, the influence of the results on antibiotic prescribing, and patient outcomes at eight days and three months.

**Methods** This was a multicentre (four centres) cross-sectional observational study including all patients with capillary CRP measurements during primary care consultations from January 1, 2022, to March 1, 2023. Patients in centre 1 were called by phone at eight days and at three months after their consultation to evaluate their recovery (patient perception).

**Results** During the study period, 91 capillary CRP measurements were performed on 90 patients. A CRP level ≥ 20 mg/L was statistically associated with antibiotic prescription (odds ratio: 12.0, 95% confidence interval: 1.91 to 75.8, *p* = 0.008). The 45 patients from centre 1 called by phone were cured of bacterial infections at three months, none were hospitalised, and 20.0% returned for another consultation.

**Conclusions** When the CRP concentration was < 20 mg/L, doctors prescribed fewer antibiotics. Antibiotic prescriptions appear to decrease in France with the use of capillary CRP.

**Keywords** Capillary CRP, General medicine, Consultations, Primary care, Antibiotic resistance

**Background**

Mortality estimates in the latest Lancet article suggest a continuing increase in mortality due to antimicrobial resistance, resulting in 1 to 91 million deaths attributable to antimicrobial resistance and 8 to 22 million deaths associated with antimicrobial resistance in 2050 [1, 2]. In 2019, the French Ministry of Health reported more than 120,000 infections caused by antibiotic-resistant bacteria, leading to 5,500 deaths in France. Overprescription of antibiotics leads to antibiotic resistance [3]. There is an urgent need to limit inappropriate antibiotic prescriptions. France ranked fourth in Europe for overuse of antibiotics in 2023 [4, 5]. Most infections are viral in origin,

<footnote>*Correspondence:
Amélie Richard
amelie.richard@uca.fr
¹Department of General Practice, Clermont Auvergne University,
Clermont-Ferrand F-63000, France</footnote>

<footnote n="2">²Clermont Auvergne University, Research Unit ACCePPT,
Clermont-Ferrand F-63000, France</footnote>

<footnote n="3">³University Multiprofessional Health Center Batignolles, Joze
F-63350, France</footnote>

<footnote n="4">⁴CHU Clermont-Ferrand, DRCI, Biostatistics Unit,
Clermont-Ferrand F-63000, France</footnote>

<footnote n="5">⁵Clermont Auvergne University, Clermont Auvergne INP, CHU Clermont-
Ferrand, CNRS, Institut Pascal, Clermont-Ferrand F-63000, France</footnote>
but there is a risk of bacterial infection, which is difficult to detect by clinical examination alone [6]. These situations of uncertainty lead to excessive and inappropriate prescribing of antibiotics [7]. In France, in 2022, 96% of doctors were asked to prescribe antibiotics for a viral infection when it was not warranted [8]. C-reactive protein (CRP), a marker of inflammation, is a diagnostic aid. Capillary CRP is a minimally invasive test that requires only a small volume of blood (1.5 to 20 µl) and is well accepted by both patients and the doctors who use it [9, 10]. This test requires less than five minutes and is part of the “point-of-care-testing” approach, with results identical to those obtained from venous sampling [10–12]. Capillary CRP in paediatric patients has shown value, especially when the fever lasts more than 12 h [6]. The probability of a bacterial infection is approximately 80% for a CRP value above 100 mg/L [13]. Capillary CRP tests in primary care, for example, in Denmark and the UK, have led to a reduction in antibiotic prescriptions [14]. A 2022 Cochrane review concluded that measuring CRP in primary care facilities likely reduces antibiotic prescriptions for acute respiratory infections; this review also concluded that the use of CRP measurement is unlikely to affect recovery rates [15]. This review highlighted the lack of data regarding age groups and 28-day mortality [15]. In France, capillary CRP measurement is rarely used [16]. Doctors have some concerns about capillary CRP, particularly missed diagnoses of bacterial infection. The latest study from December 2024 concluded, contrary to the findings of the Cochrane review, that capillary CRP measurement does not reduce antibiotic prescriptions in France for acute respiratory infections [16]. Some primary care centres (multiprofessional health centres (MHCs) and hospital paediatric consultations) are equipped with capillary CRP machines. The doctors at the centres take CRP measurements on their own initiative; there is no protocol or specific recommendations. They rely on evidence and recommendations from other countries. Capillary CRP measurement is used in different types of infections (respiratory, digestive, urological, and isolated fever) for diagnostic guidance by the doctor. Data from France regarding the help that capillary CRP measurement can provide to limit antibiotic prescriptions are contradictory. Data are also expected on mortality and cures in the weeks following the measurement.

The primary objective of this study was to assess the impact of CRP measurement results on antibiotic prescriptions in one region of France and to identify the main reasons for consultations involving the measurement of capillary CRP. The secondary objective was to assess whether failure to heal occurred following consultations with capillary CRP measurements.

## Methods

This article follows the updated guidelines from the Strengthening the Reporting of Observational studies in Epidemiology statement [17].

### Objective, design and framework of the study

This was a multicentre cross-sectional (centres 1, 2, 3, 4) and single-centre longitudinal (centre 1) observational study from January 1, 2022, to March 1, 2023, assessing the impact of CRP measurement results on antibiotic prescriptions in primary care in centres already equipped with a capillary CRP machine. Patients in centre 1 were called on day eight and at three months to assess their clinical course. A telephone survey was conducted with the patients. The patients from centre 1, who had capillary CRP measurements taken between January and April 2022, were called to collect a patient-reported assessment of their clinical course from the outset. The questionnaire was validated by a panel of experts: AR, CLap, and HVR (S1 questionnaire).

### Characteristics of participants and description of equipment

The included centres were primary care health centres in Puy-de-Dôme (France) that had a capillary CRP machine. All doctors in the centres were included regardless of their specialty (general practitioners (GPs) and paediatricians). Emergency medicine departments were excluded. The inclusion criteria were all patients from one month of age, with no upper age limit, presenting for acute reason consultation when the doctor considered it clinically necessary to perform a capillary CRP measurement. The CRP machine used was the “QuickRead Go easyCRP” (AIDIAN).

### Outcomes

The primary endpoint was the relationship between antibiotic prescriptions given to patients and capillary CRP values. Threshold values for capillary CRP were tested. The cut-off values studied were the same as those recommended by the UK National Health Service (NHS) and several other studies [14, 18, 19]. If the CRP concentration was less than 20 mg/L, no antibiotics were recommended; if it was above 100 mg/L, antibiotics were recommended.

The absence of recovery and the need for a new medical consultation or hospitalisation were investigated by a phone questionnaire at eight days and three months after the first consultation (with measurement of capillary CRP), for patients in centre 1 who had capillary CRP measurements between January and April 2022.
## Data collection

For the capillary CRP measurement during consultation, the doctors recorded the patient's name and date on a sheet available on the device. All variables were assessed by the doctors. The continuous variables used were age (in years) and CRP level (in mg/L). The categorical variables used were chronic disease (yes/no), sex (male/female), reason(s) for consultation (upper respiratory infection (yes/no), lower respiratory infection (yes/no), digestive symptoms (yes/no), other symptoms (yes/no), and follow-up (yes/no)), and patient referred to emergency services (yes/no). The Anatomical Therapeutic Chemical (ATC) classification was used for prescriptions, as follows: ATC J01 (yes/no), ATC N02 (yes/no), and ATC others (yes/no). At the eight-day and three-month follow-ups, a questionnaire was completed via telephone by the investigators with patients from centre 1 who had capillary CRP measurements between January and April 2022 (S1: Questionnaire-US).

## Statistical analysis

Statistical analysis was performed using the Stata software (version 15; StataCorp, College Station, TX, USA). All tests were two-sided, with an alpha level set at 0.05. Categorical data are expressed as the number of patients and associated percentages, and capillary CRP values are

expressed as medians [25th; 75th percentiles]. Patient characteristics were compared across the four centres via the following statistical tests: the chi-square test or Fisher's exact test for categorical data and the Kruskal-Wallis test for capillary CRP values. Factors associated with the prescription of antibiotics were studied with penalised maximum likelihood logistic regressions (Firth's method). The results are expressed as odds ratios and 95% confidence intervals. The presence of a centre effect was tested with a mixed effect model. Since the intraclass correlation coefficient was null, the centre was not taken into account in the analyses. Owing to the small number of antibiotic prescriptions, no multivariable analysis was performed. Exploratory subgroup analyses (according to reasons for consultation and age groups) were performed to assess the associations between capillary CRP values and antibiotic prescription.

## Results

### Description of centres

The four primary care centres with a capillary CRP machine in Puy-de-Dôme agreed to participate in this study. The MHC in Saint-Eloy-les-Mines (centre 1) recruited 49 patients (50 capillary measurements), the paediatric consultation service at Thiers Hospital (centre 2) recruited 10 patients, the University MHC in Joze

<table><caption>**Table 1** Description of the sample according to the four centres</caption><thead><tr><th></th><th>Total<br>(n=91)</th><th>Centre 1<br>(n=50)</th><th>Centre 2<br>(n=10)</th><th>Centre 3<br>(n=22)</th><th>Centre 4<br>(n=9)</th><th>p</th></tr></thead><tbody><tr><td>Age</td><td></td><td></td><td></td><td></td><td></td><td>&lt;0.001</td></tr><tr><td>&lt;6 years</td><td>31 (34.1)</td><td>7 (14.0)</td><td>10 (100)</td><td>13 (59.1)</td><td>1 (11.1)</td><td></td></tr><tr><td>6 to 15 years</td><td>29 (31.9)</td><td>12 (24.0)</td><td>0 (0)</td><td>9 (40.9)</td><td>8 (88.9)</td><td></td></tr><tr><td>16 to 64 years</td><td>23 (25.3)</td><td>23 (46.0)</td><td>0 (0)</td><td>0 (0)</td><td>0 (0)</td><td></td></tr><tr><td>≥ 65 years</td><td>8 (8.8)</td><td>8 (16.0)</td><td>0 (0)</td><td>0 (0)</td><td>0 (0)</td><td></td></tr><tr><td>Male sex</td><td>57 (62.6)</td><td>35 (70.0)</td><td>5 (50.0)</td><td>11 (50.0)</td><td>6 (66.7)</td><td>0.32</td></tr><tr><td>Reason(s) for consultation</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Upper respiratory infection</td><td>60 (65.9)</td><td>26 (52.0)</td><td>7 (70.0)</td><td>19 (86.4)</td><td>8 (88.9)</td><td>0.01</td></tr><tr><td>Lower respiratory infection</td><td>10 (11.0)</td><td>2 (4.0)</td><td>1 (10.0)</td><td>5 (22.7)</td><td>2 (22.2)</td><td>0.04</td></tr><tr><td>Digestive symptoms</td><td>16 (17.6)</td><td>13 (26.0)</td><td>1 (10.0)</td><td>1 (4.5)</td><td>1 (11.1)</td><td>0.12</td></tr><tr><td>Other symptoms<sup>a</sup></td><td>14 (15.4)</td><td>9 (18.0)</td><td>2 (20.0)</td><td>3 (13.6)</td><td>0 (0)</td><td>0.65</td></tr><tr><td>Follow-up</td><td>1 (1.1)</td><td>1 (2.0)</td><td>0 (0)</td><td>0 (0)</td><td>0 (0)</td><td>1.00</td></tr><tr><td>Chronic illness</td><td>18 (19.8)</td><td>17 (34.0)</td><td>0 (0)</td><td>0 (0)</td><td>1 (11.1)</td><td>0.001</td></tr><tr><td>Drug prescription(s)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Antibiotics</td><td>7 (7.7)</td><td>4 (8.0)</td><td>0 (0)</td><td>2 (9.1)</td><td>1 (11.1)</td><td>0.87</td></tr><tr><td>Curative treatment</td><td>5 (5.5)</td><td>5 (10.0)</td><td>0 (0)</td><td>0 (0)</td><td>0 (0)</td><td>0.40</td></tr><tr><td>Symptomatic treatment</td><td>63 (69.2)</td><td>37 (74.0)</td><td>7 (70.0)</td><td>16 (72.7)</td><td>3 (33.3)</td><td>0.13</td></tr><tr><td>None</td><td>19 (20.9)</td><td>6 (12.0)</td><td>3 (30.0)</td><td>5 (22.7)</td><td>5 (55.6)</td><td>0.02</td></tr><tr><td>Referral to emergency department</td><td>6 (6.6)</td><td>5 (10.0)</td><td>0 (0)</td><td>0 (0)</td><td>1 (11.1)</td><td>0.34</td></tr><tr><td>Capillary CRP (mg/L)</td><td>6.1 [1.7; 23.0]</td><td>7.3 [2.6; 22.0]</td><td>0.0 [0.0; 0.0]</td><td>4.5 [1.3; 21.0]</td><td>23.0 [6.7; 38.0]</td><td>0.005</td></tr><tr><td>Capillary CRP ≥ 20 mg/L</td><td>28 (30.8)</td><td>16 (32.0)</td><td>1 (10.0)</td><td>6 (27.3)</td><td>5 (55.6)</td><td>0.21</td></tr></tbody></table>

Data are presented as numbers (percentages in column), or median [25th; 75th percentiles]

Abbreviations: CRP C-reactive protein

<footnote>ªDermatological symptoms, urological symptoms, neurological symptoms, and isolated fever</footnote>
(centre 3) recruited 22 patients, and the Dorat site of the University MHC (centre 4) recruited 9 patients. There were 11 physician investigators and 10 medical students in the four centres (S2-Characteristics of the doctors).

## Description of the sample according to the four centres

The sample consisted of 91 capillary CRP measurements (90 patients) taken in primary care (Table 1). Children under the age of 16 accounted for two-thirds of the sample. Patients consulting during this period for acute infections were the usual patients in the medical practice. The main reason for consultation was upper respiratory infections (65.9%). The median CRP concentration was 6.1 mg/L [1.7; 23.0], with 63 values (69.2%) between 0 and 19 mg/L, 25 values (27.5%) between 20 and 99 mg/L, and 3 values (3.3%) ≥ 100 mg/L (Fig. 1). The intake in the four centres was different, particularly with a population of children aged 1 month to 15 years in centres 2, 3 and 4.

## Antibiotic prescription

Among the 91 capillary CRP measurements, seven (7.7%) were followed by antibiotic prescription (including two with associated symptomatic treatment). No

deferred prescriptions were issued. The antibiotics prescribed were cefixime (ATC: J01DD08, n = 1), selexid (ATC: J01CA08, n = 1), amoxicillin (ATC: J01CR02, n = 4), and clarithromycin (ATC: J01FA09, n = 1). A CRP level ≥ 20 mg/L was statistically associated with antibiotic prescription (odds ratio: 12.0, 95% confidence interval: 1.91 to 75.8, *p* = 0.008) (Table 2). Among the three patients with a CRP ≥ 100 mg/L, one had an upper respiratory infection and no antibiotic prescription, one had digestive symptoms and an antibiotic prescription, and one had upper and lower respiratory infections and an antibiotic prescription. Other factors associated with the prescription of antibiotics were the presence of a lower respiratory infection (*p* = 0.008), and the absence of prescription of symptomatic treatment (*p* = 0.03). It does not seem appropriate to perform a multivariable analysis due to the very small number of antibiotic prescriptions (*n* = 7). The estimates are highly imprecise, with large odds ratios and wide confidence intervals. However, we have conducted single-variable adjusted analyses (Table 2). Regardless of the reason for consultation or the age group, antibiotics were more commonly prescribed when the CRP level was ≥ 20 mg/L (Table 3).

## Other treatments

Symptomatic treatments were prescribed more often when the CRP level was < 20 mg/L (79.4% vs. 46.4%, *p* = 0.003). Symptomatic treatments included paracetamol (ATC: NO2BE01, n = 26), and ATC others included colchicine (ATC: M04AC01, n = 1), valaciclovir (ATC: J05AB11, n = 1), and fusidic acid (D06AX01, n = 1). Prescription-free consultation (PFC) accounted for 15% of acute consultations with CRP measurements in our study.

<table><caption>**Table 2** Association between capillary CRP values (≥ 20 mg/L compared to < 20 mg/L) and antibiotic prescription</caption><thead><tr><th></th><th>OR [95%CI]</th><th>p</th></tr></thead><tbody><tr><td>Unadjusted</td><td>12.0 [1.9; 75.8]</td><td>0.008</td></tr><tr><td>Adjusted for age</td><td>9.9 [1.6; 60.3]</td><td>0.01</td></tr><tr><td>Adjusted for sex</td><td>18.7 [2.4; 144]</td><td>0.005</td></tr><tr><td>Adjusted for upper respiratory infection</td><td>11.5 [1.8; 71.6]</td><td>0.009</td></tr><tr><td>Adjusted for lower respiratory infection</td><td>16.5 [2.1; 130]</td><td>0.008</td></tr><tr><td>Adjusted for digestive symptoms</td><td>11.7 [1.9; 72.8]</td><td>0.009</td></tr><tr><td>Adjusted for other symptoms<sup>a</sup></td><td>11.3 [1.8; 70.5]</td><td>0.009</td></tr><tr><td>Adjusted for prescription of a symptomatic treatment</td><td>8.3 [1.2; 55.7]</td><td>0.03</td></tr><tr><td>Adjusted for referral to emergency department</td><td>13.1 [2.0; 86.0]</td><td>0.007</td></tr><tr><td>Adjusted for centre</td><td>10.1 [1.7; 61.3]</td><td>0.01</td></tr></tbody></table>

Abbreviations: CI Confidence interval, OR Odds ratio, Ref Reference

<figure><img src="image_4.png" /><figcaption>**Fig. 1** Distribution of capillary C-reactive protein values (n = 91). CRP: C-reactive protein. The central mark is the median, the edges of the box are the 25th and 75th percentiles, the upper whisker is calculated as the maximum (75th percentile + 1.5 x (75th percentile - 25th percentile)), the lower whisker is calculated as the minimum (25th percentile - 1.5 x (75th percentile - 25th percentile)), and the dots are outliers</figcaption></figure>

<footnote><sup>a</sup>Dermatological symptoms, urological symptoms, neurological symptoms, isolated fever</footnote>
<table><caption>**Table 3** Subgroup analyses</caption><thead><tr><th></th><th></th><th>n</th><th>No antibiotic prescription (n=84)</th><th>Antibiotic prescription (n=7)</th><th>OR [95% CI]</th><th>p</th></tr></thead><tbody><tr><td rowspan="2">Upper respiratory infection</td><td>Capillary CRP</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>&lt; 20 mg/L</td><td>43</td><td>42 (97.7)</td><td>1 (2.3)</td><td>Ref</td><td></td></tr><tr><td></td><td>≥ 20 mg/L</td><td>17</td><td>14 (82.4)</td><td>3 (17.6)</td><td>6.84 [0.92; 50.7]</td><td>0.06</td></tr><tr><td rowspan="2">Lower respiratory infection</td><td>Capillary CRP</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>&lt; 20 mg/L</td><td>7</td><td>6 (85.7)</td><td>1 (14.3)</td><td>Ref</td><td></td></tr><tr><td></td><td>≥ 20 mg/L</td><td>3</td><td>1 (33.3)</td><td>2 (66.7)</td><td>7.22 [0.49; 107]</td><td>0.15</td></tr><tr><td rowspan="2">Digestive symptoms</td><td>Capillary CRP</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>&lt; 20 mg/L</td><td>11</td><td>11 (100)</td><td>0 (0)</td><td>Ref</td><td></td></tr><tr><td></td><td>≥ 20 mg/L</td><td>5</td><td>4 (80.0)</td><td>1 (20.0)</td><td>7.67 [0.26; 225]</td><td>0.24</td></tr><tr><td rowspan="2">Other symptoms<sup>a</sup></td><td>Capillary CRP</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>&lt; 20 mg/L</td><td>9</td><td>9 (100)</td><td>0 (0)</td><td>Ref</td><td></td></tr><tr><td></td><td>≥ 20 mg/L</td><td>5</td><td>3 (60.0)</td><td>2 (40.0)</td><td>13.57 [0.51; 359]</td><td>0.12</td></tr><tr><td rowspan="2">Age &lt; 6 years</td><td>Capillary CRP</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>&lt; 20 mg/L</td><td>24</td><td>24 (100)</td><td>0 (0)</td><td>Ref</td><td></td></tr><tr><td></td><td>≥ 20 mg/L</td><td>7</td><td>6 (85.7)</td><td>1 (14.3)</td><td>11.31 [0.41; 311]</td><td>0.15</td></tr><tr><td rowspan="2">Age 6 to 15 years</td><td>Capillary CRP</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>&lt; 20 mg/L</td><td>18</td><td>17 (94.4)</td><td>1 (5.6)</td><td>Ref</td><td></td></tr><tr><td></td><td>≥ 20 mg/L</td><td>11</td><td>9 (81.8)</td><td>2 (18.2)</td><td>3.07 [0.35; 27.0]</td><td>0.31</td></tr><tr><td rowspan="2">Age 16 to 64 years</td><td>Capillary CRP</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>&lt; 20 mg/L</td><td>16</td><td>16 (100)</td><td>0 (0)</td><td>Ref</td><td></td></tr><tr><td></td><td>≥ 20 mg/L</td><td>7</td><td>5 (71.4)</td><td>2 (28.6)</td><td>15.00 [0.62; 363]</td><td>0.10</td></tr><tr><td rowspan="2">Age ≥ 65 years</td><td>Capillary CRP</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>&lt; 20 mg/L</td><td>5</td><td>5 (100)</td><td>0 (0)</td><td>Ref</td><td></td></tr><tr><td></td><td>≥ 20 mg/L</td><td>3</td><td>2 (66.7)</td><td>1 (33.3)</td><td>6.60 [0.19; 226]</td><td>0.30</td></tr></tbody></table>

Data are presented as numbers (percentages in row).

Abbreviations: CI Confidence interval, CRP C-reactive protein, OR Odds ratio, Ref Reference

## Follow-up of patients at centre 1

The 47 patients from centre 1 tested between January and April 2022 were called on day eight and at three months after the measurement of capillary CRP to determine how their clinical course had progressed. These patients were all from centre 1 and were tested from January to April 2022 (the other three patients recruited in centre 1 were recruited after April 2022). One patient was lost to follow-up (no response after three unsuccessful calls), one patient returned twice for consultation at the MHC and had two CRP values, and the other 45 patients were cured at three months (including 13 between the eighth day and the third month). Nevertheless, 20.0% of patients (9/45) had seen a GP again or gone to the emergency department, all within eight days of the first consultation (Table 4 and Fig. 2). A single addition of antibiotics was reported for a four-year-old child. The median CRP level was 4.9 mg/L [2.4; 15.0] for patients cured on day 8 (n=32), 9.6 mg/L [3.2; 25.0] for patients who improved (n=8), and 19.0 mg/L [13.0; 50.0] for stable patients (n=5) (p=0.25) (Fig. 3).

## Discussion

### Main results

Prescriptions were significantly associated with the CRP value: antibiotics were less commonly prescribed in patients with a CRP level < 20 mg/L. Among the 91 patients, the reasons for consultation were evenly distributed between upper and lower respiratory infections and digestive symptoms. The 45 patients called from centre 1 were cured at three months, with no hospitalisations. Among the 20% of patients (9/45) with a return consultation, only one antibiotic was added for a 4-year-old child. The median CRP was 4.9 mg/L [2.4; 15.0] for patients cured on day 8, 9.6 mg/L [3.2; 25.0] for patients who improved, and 19.0 mg/L [13.0; 50.0] for stable patients; no patient worsened.

### Strengths and weaknesses

The strengths of this study were its inclusion of primary care patients ≤ 6 years old, its consideration of frailty, and its setting in a country where capillary CRP measurement at GP offices remains rare. The study brought together

<footnote><sup>a</sup>Dermatological symptoms, urological symptoms, neurological symptoms, and isolated fever</footnote>
<table><caption>**Table 4** Survey by phone</caption><thead><tr><th></th><th>Centre 1<br>(n = 45*)</th></tr></thead><tbody><tr><td>First consultation</td><td></td></tr><tr><td>Age</td><td></td></tr><tr><td>&lt; 6 years</td><td>6 (13.3)</td></tr><tr><td>6 to 15 years</td><td>10 (22.2)</td></tr><tr><td>16 to 64 years</td><td>22 (48.9)</td></tr><tr><td>≥ 65 years</td><td>7 (15.6)</td></tr><tr><td>Male sex</td><td>32 (71.1)</td></tr><tr><td>Antibiotics prescription</td><td>4 (8.9)</td></tr><tr><td>Capillary CRP (mg/L)</td><td>6.3 [2.6; 21.0]</td></tr><tr><td>Capillary CRP ≥ 20 mg/L</td><td>12 (26.7)</td></tr><tr><td>Day 8 phone call</td><td></td></tr><tr><td>Patients cured</td><td>32 (71.1)</td></tr><tr><td>Patients improved</td><td>8 (17.8)</td></tr><tr><td>Patients stable</td><td>5 (11.1)</td></tr><tr><td>Taking antibiotics</td><td>4/4 (100)</td></tr><tr><td>New consultation with a doctor in the last 8 days</td><td>9 (20.0)</td></tr><tr><td>Emergency consultation, new consultation with GP</td><td>6/9 (66.7)</td></tr><tr><td>Repeat visit to GP</td><td>3/9 (33.3)</td></tr><tr><td>Treatment modification</td><td></td></tr><tr><td>Antibiotic introduction</td><td>1/9 (11.1)</td></tr><tr><td>Change of antibiotic</td><td>0/9 (0)</td></tr><tr><td>Additional tests</td><td></td></tr><tr><td>Biology</td><td>1/9 (11.1)</td></tr><tr><td>Imaging</td><td>1/9 (11.1)</td></tr><tr><td>Hospitalisation</td><td>0 (0)</td></tr><tr><td>3 month phone call</td><td></td></tr><tr><td>Recovery</td><td>13/13 (100)</td></tr></tbody></table>

Data are presented as numbers (percentages in column), or median [25th; 75th percentiles]

Abbreviations: CRP C-reactive protein

*47 patients in centre 1 were tested from January to April 2022 (the other three patients from centre 1 were recruited after April 2022), 1 missing, 1 duplicate

primary care centres in France using a capillary CRP machine. There are few data on consultations and follow-up in primary care, and this study provides data on these consultations (reasons for consultations in particular). This study was the starting point for a research protocol in France: ACROPOLE (Antibiotic therapy and capillary CRP: contributiOn PrescriptiOns in generaL mEdicine), a cluster randomised trial to measure the impact of using capillary CRP measurements to reduce inappropriate antibiotic prescriptions [20].

Nevertheless, this study has the following limitations: the number of participants was modest, and subgroup analyses were not sufficiently powered. Furthermore, we were only able to collect a limited amount of data. There were only three values above 100 mg/L CRP, which meant that the planned threshold values could not be maintained. Only the threshold of 20 mg/L was retained for statistical testing. The first 47 patients from centre 1 were called to determine how their clinical course had

progressed. The telephone questionnaire used in this study was not a validated questionnaire.

## Low antibiotic prescription rate

This study is based on fieldwork and practice, with doctors performing CRP to aid their diagnosis in the clinical circumstances of their choice. French GPs (80%) find it difficult to refuse antibiotics to patients [8]. Measuring CRP in the context of a viral infection has certainly helped them in discussions with patients to validate a viral infection and avoid antibiotic prescriptions. In fact, in the 2022 data, GPs reported prescribing 85% less than 20% of antibiotics in 16–65-year-olds (data from the Remuneration for Public Health Objectives (ROSP) in France) [8]. However, in our study, antibiotic prescriptions were 8%, which is well below what has been reported by the ROSP in France. Conducting the CRP in various clinical contexts, reflecting typical primary care activity, has probably helped doctors prescribe fewer antibiotics.

## Prescriptions, over-the-counter consultations and capillary CRP measurement in France

Antibiotics were less commonly prescribed when the CRP level was < 20 mg/L (1.6% vs. 21.4%, *p* = 0.008). Symptomatic treatments were prescribed more often when the CRP level was < 20 mg/L (79.4% vs. 46.4%, *p* = 0.003). Instead of conducting a prescription-free consultation (PFC) when an antibiotic seems unnecessary, French GPs prescribe symptomatic treatments, sometimes not reimbursed, sometimes without proof of their efficacy, with low medical services rendered [21]. GPs appeared to be attached to prescribing medication in our study, as in other studies [22]. PFCs accounted for 15% of acute consultations with CRP measurements in our study; in Belgium in 2009, 36% of consultations for acute reasons ended in a prescription-free consultation [23]. Our study confirms that consultations for acute reasons limit PFCs in France [24]. GPs overestimate the number of acute patients waiting for a drug prescription [25]. According to the World Organization of Family Doctors, “many consultations serve to calm the anxiety linked to the possible illnesses of patients who have no pathology” and could end without treatment [26]. The leading cause of pollution in the health care sector is drug prescribing [27].

## New consultation, evolution

A total of 45 patients in centre 1 were cured at three months, and none were hospitalised. Multiple consultations are a factor in inappropriate antibiotic prescribing, with the doctor prescribing more antibiotics when it is the second or third contact [28]. Among the nine patients who returned for another consultation, only one
<figure><img src="image_5.png" /><figcaption>**Fig. 2** Patient follow-up at centre 1 (n = 45). ATB: antibiotic prescription, CRP: C-reactive protein, GP: general practitioner</figcaption></figure>

<figure><img src="image_6.png" /><figcaption>**Fig. 3** Patient status and new consultations on day 8, according to their capillary C-reactive protein value during the first consultation (n = 45). CRP: C-reactive protein</figcaption></figure>

antibiotic was added for a 4-year-old child. In 2024, Jung et al. also called patients on day 8. In their study, antibiotics were taken by 59% (26/44) of the contacted patients with prescriptions. Among the patients contacted on day 8, 19% (62/331) saw a doctor within eight days of the index consultation, and one 20-year-old patient had been in the emergency room. None of the patients were hospitalised. The results were similar to those of our study.

### ACROPOLE

A randomised trial protocol, "Antibiotic therapy and capillary CRP: contributiOn on PrescriptiOns in generaL mEdicine (ACROPOLE)", was written to test whether

measuring capillary CRP helps doctors prescribe fewer antibiotics. This pilot study will provide input for improving ACROPOLE. Indeed, in primary care, all consultation reasons are of interest for the use of capillary CRP measurement, so ACROPOLE cannot be limited to respiratory infections in France. The case of children is also interesting, and age classes will be created to evaluate the 20 mg/L threshold in children under six years of age.

### Comparison with other European countries

In Europe, the use of capillary CRP is heterogeneous, with seven European countries routinely using capillary CRP: Switzerland, Denmark, Finland, Sweden, Norway,
Germany and the Netherlands [29]. The Dutch College of GPs has issued recommendations for respiratory tract infections on the basis of capillary CRP. A randomised cluster trial by Cals demonstrated the efficacy of capillary CRP levels in conjunction with the clinic in diagnosing pneumopathy [30]. The NHS and National Institute for Health and Care Excellence have issued recommendations for lower respiratory tract infections [14]. During a consultation for rhinopharyngitis in the Netherlands, the GP does not prescribe, but reassures, informs and ends the consultation; in comparison, the organisation of care in France places the drug prescription at the heart of the doctor/patient relationship, according to A. Rosman [31, 32].

## Health expenditure

Several European studies have shown that the use of capillary CRP measurement reduces the need for laboratory prescriptions (bacteria culture test, serum CRP, and urine cytobacteriological examination) [6, 29, 33]. The measurement of capillary CRP by GPs is more effective than laboratory measurements in reducing antibiotic prescriptions [34]. The average cost of a capillary CRP test is estimated at €7, which is payable by the practitioner. In France, an automated capillary CRP test costs between €1,000 and €6,000, depending on the model. In Switzerland, medical insurance companies reimburse tests. In Sweden, the procedure is free for both doctors and patients [29].

## Conclusions

Doctors took capillary CRP measurements on the basis of their clinical analysis of acute consultations, which were mainly respiratory (66%). There was a statistically significant association between drug use and the CRP level. When the CRP concentration was less than 20 mg/L, doctors prescribed fewer antibiotics and more symptomatic treatments. The 45 patients who were called at eight days and three months after the capillary CRP test all recovered. A total of 20% of these 45 patients returned for another consultation. The increase in new consultations was associated with a proven reduction in antibiotic prescriptions.

### Abbreviations

<table><tr><td>ACROPOLE</td><td>Antibiotic therapy and capillary CRP: contribution on PrescriptiOns in general mEdicine</td></tr><tr><td>ATC</td><td>Anatomical therapeutic chemical</td></tr><tr><td>CRP</td><td>C-reactive protein</td></tr><tr><td>GP</td><td>General practitioner</td></tr><tr><td>MHC</td><td>Multiprofessional Health Centre</td></tr><tr><td>NHS</td><td>National Health Service</td></tr><tr><td>PFC</td><td>Prescription-free consultation</td></tr><tr><td>ROSP</td><td>Remuneration for Public Health Objectives</td></tr></table>

## Supplementary Information

The online version contains supplemental material available at https://doi.org/10.1186/s12875-025-02924-9.

Supplementary Material 1.

Supplementary Material 2.

### Acknowledgements

Not applicable.

### Authors' contributions

AR designed the study, monitored its progress and wrote the first versions of the article, CLam carried out the statistical analyses and participated in the writing and methodology, PB participated in the writing and monitored the data collection, HVR participated as a major author and directed the writing, and CLap directed the progress of the study and the writing. All the authors read and approved the final manuscript.

### Funding

Not applicable.

### Data availability

The datasets used and/or analysed in this study are available from the corresponding author upon reasonable request.

## Declarations

### Ethics approval and consent to participate

A favourable opinion was obtained from the "Comité de Protection des Personnes Sud Est VI" (Reference 2022/CE 50 amended on 07/04/2023). "Comité de protection des personnes" is an institutional review board. Authorisation from the "Commission Nationale de l'Informatique et des Libertés" was obtained on July 23, 2022, for centres 1 and 4 and on September 13, 2022, for centres 2 and 3.

For patients at centre 1, a declaration to the "Commission Nationale de l'Informatique et des Libertés" was issued on April 23, 2022. A request was made to the "Comité de Protection des Personnes Sud Est VI", and a favourable opinion was issued on April 7, 2023 (reference 2023/CE 09). This observational and prospective study does not raise any particular ethical issues and does not fall within the scope of the regulations governing biomedical research, as defined in Article L.1121-1 and Articles R.1121-1 and R.1121-2.

Our study complied with the Declaration of Helsinki.

An explanatory poster in the waiting room informed patients about the study so that they could object to the use of their data. Informed oral consent was obtained from all patients. An information sheet was given to the parents of the children tested, all parents' informed consent was obtained.

### Consent to publication

Not applicable.

### Competing interests

The authors declare no competing interests.

Received: 9 January 2025 / Accepted: 23 June 2025

Published online: 28 August 2025

### References

1. UN Interagency Coordination Group on Antimicrobial Resistance presents its report to the UN SG. Disponible sur: https://www.who.int/news/item/28-04-2019-un-interagency-coordination-group-on-antimicrobial-resistance-present-s-its-report-to-the-un-sg. [cité 24 oct 2024].

2. Naghavi M, Vollset SE, Ikuta KS, Swetschinski LR, Gray AP, Wool EE, et al. Global burden of bacterial antimicrobial resistance 1990–2021: a systematic analysis with forecasts to 2050. Lancet. 2024;404(10459):1199–226.
3. Poirel L, Madec JY, Lupo A, Schink AK, Kieffer N, Nordmann P et al. Antimicrobial resistance in escherichia coli. microbiology spectrum. 2018;6(4). https://doi.org/10.1128/microbiolspec.arba-0026-2017.

4. Browne AJ, Chipeta MG, Haines-Woodhouse G, Kumaran EPA, Hamadani BHK, Zaraa S, et al. Global antibiotic consumption and usage in humans, 2000–18: a spatial modelling study. Lancet Planet Health. 2021;5(12):e893-904.

5. SPF. La consommation d'antibiotiques en secteur de ville en France 2009-2019. Synthèse préliminaire des indicateurs disponibles sous Géodes. Disponible sur: https://www.santepubliquefrance.fr/import/la-consommation-d-antibiotiques-en-secteur-de-ville-en-france-2009-2019-synthese-preliminaire-des-indicateurs-disponibles-sous-geodes. [cité 24 oct 2024].

6. Van den Bruel A, Haj-Hassan T, Thompson M, Buntinx F, Mant D, European Research Network on Recognising Serious Infection investigators. Diagnostic value of clinical features at presentation to identify serious infection in children in developed countries: a systematic review. Lancet. 2010;375(9717):834-45.

7. Llor C, Moragas A, Cots JM, López-Valcárcel RG, Happy Audit Study Group. Estimated saving of antibiotics in pharyngitis and lower respiratory tract infections if general practitioners used rapid tests and followed guidelines. Aten Primaria. 2017;49(6):319-25.

8. Verger P, Fressard L, Jacquemot AF, Bergeat M, Vergier N, Pulcini C et al (2022) Un médecin généraliste sur deux est confronté à des problèmes d'antibiorésistance. Drees. 2022;(1217). Disponible sur: https://drees.solidarite-s-sante.gouv.fr/sites/default/files/2022-01/ER1217.pdf.

9. Ragimbeau R, Kessy G serg. Intérêt du dosage de la CRP par une méthode de biologie délocalisée [Thèse d'exercice médecine]. Lille; 2018. Disponible sur: https://pepite-depot.univ-lille.fr/LIBRE/Th_Médecine/2018/2018LILUM047.pdf. [cité 1 janv 2024].

10. Morioka K, Sato H, Kuboyama M, Yanagida A, Shoji A. Quantification of CRP in human serum using a handheld fluorescence detection system for capillary-based ELISA. Talanta. 2021. https://doi.org/10.1016/j.talanta.2020.121725.

11. Rouliaud M, Pereira B, Cosme J, Mourgues C, Sarret C, Sapin V et al (2018) Evaluation of the capillary assay of C-reactive protein (CRP) through the length of consultation in pediatric emergencies and its economic impact. Ann Biol Clin (Paris). 76(5):545-52

12. Hobbs FD, Kenkre JE, Carter YH, Thorpe GH, Holder RL. Reliability and feasibility of a near patient test for C-reactive protein in primary care. Br J Gen Pract. 1996;46(408):395-400.

13. Rondeau A. Le test rapide de la CRP en médecine libérale: état des lieux et perspectives. 2014;7:64.

14. Huddy JR, Ni MZ, Barlow J, Majeed A, Hanna GB. Point-of-care C reactive protein for the diagnosis of lower respiratory tract infection in NHS primary care: a qualitative study of barriers and facilitators to adoption. BMJ Open. 2016. https://doi.org/10.1136/bmjopen-2015-009959.

15. Smedemark SA, Aabenhus R, Llor C, Fournaise A, Olsen O, Jørgensen KJ. Biomarkers as point-of-care tests to guide prescription of antibiotics in people with acute respiratory infections in primary care - Smedemark, SA - 2022 | Cochrane Library. Disponible sur: https://doi.org/10.1002/14651858.CD010130.pub3/full. [cité 4 mars 2025].

16. Jung C, Levy C, Béchet S, Aegerter P, Cohen R, Touitou R. Impact of C-reactive protein point-of-care testing on antibiotic prescriptions for children and adults with suspected respiratory tract infections in primary care: a French patient-level randomized controlled superiority trial. Clin Microbiol Infect. 2024;30(12):1553-8.

17. von Elm E, Altman DG, Egger M, Pocock SJ, Gøtzsche PC, Vandenbroucke JP. The strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. Lancet. 2007;370(9596):1453-7.

18. Putto A, Ruuskanen O, Meurman O, Ekblad H, Korvenranttä H, Mertsola J, et al. C reactive protein in the evaluation of febrile illness. Arch Dis Childhood. 1986;61(1):24-9.

19. Korppi M, Kröger L. C-reactive protein in viral and bacterial respiratory infection in children. Scand J Infect Dis. 1993;25(2):207-13.

20. ISRCTN - ISRCTN45343680: Impact of rapid diagnostic tests for capillary C-reactive protein (CRP) on antibiotic use in general medicine. Disponible sur: https://www.isrctn.com/ISRCTN45343680. [cité 24 oct 2024].

21. Bergmann JF. Médicaments utiles et inutiles: notion de service médical rendu. EMC - Médecine. 2004;1(1):51-8

22. Deleplanque D, Hennion-Gasrel F, Diblanc-Stamm A, Rochoy M, Messaadi N. Consultations without drug prescription: doctors and patients perceptions. Exercer. 2015;26:13-21.

23. Matthys J, Elwyn G, Van Nuland M, Van Maele G, De Sutter A, De Meyere M, et al. Patients' ideas, concerns, and expectations (ICE) in general practice: impact on prescribing. Br J Gen Pract. 2009;59(558):29-36.

24. Masson E. EM-Consulte. Prescription-free consultation: a cross-sectional study in general practice. Disponible sur: https://www.em-consulte.com/article/1667826/prescription-free-consultation-a-cross-sectional-s. [cité 24 oct 2024].

25. Masson E. EM-Consulte. Prescription-free consultation in France and Europe: Rates' evolution, physicians' and patients' perceptions from 2005 to 2019, a systematic review. Disponible sur: https://www.em-consulte.com/article/1578274/prescription-free-consultation-in-france-and-europ. [cité 18 juil 2023].

26. Allen DJ, Heyrman PJ. WONCA Europe. 2002. La définition européenne de la médecine générale-médecine de famille. Disponible sur: https://www.wonca.europa.org/file/afaa93f5-dc46-4b0e-8546-71ebf368f41c/WONCA%20definition%20French%20version.pdf. [cité 28 juin 2022].

27. Note-technique-Facteurs-demissions-des-medicaments-18042023.pdf. Disponible sur: https://theshiftproject.org/wp-content/uploads/2023/04/Note-technique-Facteurs-demissions-des-medicaments-18042023.pdf. [cité 28 nov 2024].

28. Attali C. Méthodologie de l'étude PAAIR II. Médecine et Maladies Infectieuses. 2005;35:587-9

29. Dacquin R, Charles R, Bruel S. Les modèles suisses et anglais de mesure de la CRP en soins premiers: applicabilité au modèle français? Exercer. 2021;175:307-13

30. Cals JWL, Ament AJHA, Hood K, Butler CC, Hopstaken RM, Wassink GF, et al. C-reactive protein point of care testing and physician communication skills training for lower respiratory tract infections in general practice: economic evaluation of a cluster randomized trial. J Eval Clin Pract. 2011;17(6):1059-69.

31. Haute Autorité de Santé. 2011. Développement de la prescription de thérapeutiques non médicamenteuses validées. Disponible sur: https://www.has-sante.fr/jcms/c_1059795/fr/developpement-de-la-prescription-de-therapeutes-non-médicamenteuses-validées. [cité 23 juin 2022].

32. Rosman S. Les pratiques de prescription des médecins généralistes. Une étude sociologique comparative entre la France et les Pays-Bas. Rennes (France): Presses de l'EHESP; 2010. Disponible sur: https://www.cairn.info/singuliers-generalistes-9782810900213-page-117.htm. [cité 3 nov 2021].

33. Lemienyre MB, van Driel ML, Merenstein D, Liira H, Mäkelä M, De Sutter Al. Antibiotics for acute rhinosinusitis in adults. Cochrane Database Syst Rev. 2018;9:CD006089

34. Kokko E, Korppi M, Helminen M, Hutri-Kähönen N. Rapid C-reactive protein and white cell tests decrease cost and shorten emergency visits. Pediatr Int. 2014;56(5):698-701.

## Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.