What a difference a CRP makes. A prospective observational study on how point-of-care C-reactive protein testing influences antibiotic prescription for respiratory tract infections in Swedish primary health care

Figures & data

Table 1. Number of patient visits to physicians in primary health care (n = 340).

Physician’s educational status	n (%)
Specialist in family medicine (GP)	194 (57)
Non-specialist GP:	146 (43)
GP trainee/resident, family medicine	67 (20)
Physician with medical licence	40 (12)
Physician in clinical internship	28 (8.2)
Graduated/non-licensed MD^1	3 (0.9)
Other	5 (1.5)
Unknown	3 (0.9)

1 Physicians with medical school examination but without licence.

Figure 1. Consultation process and decision-making in chronological order.^aCase report form.

Figure 2. Participant flow.

Figure 3. Bland–Altman limits of agreement plot for CRP estimates and measured values.

Table 2. Differences in C-reactive protein (CRP) estimations between visits to family medicine specialists (GP group) and physicians with other educational status (non-specialist GP group) in primary health care.

	Visits to GP group (n = 194)	Visits to non-specialist GP group (n = 146)	p-values^1
CRP crucial for treatment, yes, n (%)^2	65 (34)	65 (45)	0.038
Physician’s estimate of CRP (mg/L)^3	24 (19)	29 (26)	0.039
Differences between estimated and measured CRP (mg/L)^3	−1.4 (29)	2.1 (33)	0.30

Notes:

1 Student’s t-test for comparison of quantitative data and chi-square test for qualitative data.

2 2.6% (n = 9) did not check the “yes” or “no” box on the case report form, four in the GP group, five in the non-specialist GP group.

3 Mean values (standard deviation).

Table 3. Physician behaviour in light of their opinion on antibiotic prescription issues prior to C-reactive protein (CRP) testing, after viewing the actual CRP level.¹

	Antibiotics retracted[n (%)]	Decision unchanged[n (%)]	Antibiotics prescribed[n (%)]	p Values^2
Visits to GP group (n = 190)				0.22
CRP crucial for treatment	2 (3.1)	53 (82)	10 (15)
CRP unnecessary for treatment	2 (1.6)	113 (90)	10 (8.0)
Visits to non-specialist GP group (n = 141)				0.011
CRP crucial for treatment	9 (14)	48 (74)	8 (12)
CRP unnecessary for treatment	1 (1.3)	68 (90)	7 (9.2)
Total visits (n = 331)^3				0.0018
CRP crucial for treatment	11 (8.5)	101 (78)	18 (14)
CRP unnecessary for treatment	3 (1.5)	181 (90)	17 (8.5)

1 “Antibiotics retracted” and “Antibiotics prescribed” means change in approach to prescribing antibiotics.

2 Chi-square test.

3 2.6% (n = 9) did not check the “yes” or “no” box on the case report form, four in the GP group, five in the non-specialist GP group.

Table 4. Logistic regression analysis showing odds ratio for physician’s change in approach to prescribing antibiotics: Pre-CRP testing unwilling to prescribe antibiotics changing to prescribe antibiotics post-CRP testing and vice versa as dependent variable (1).

	Unadjusted odds ratio (CI 95%)	p Values	Adjusted odds ratio (CI 95%)	p Values
Sex (female 1)	1.5 (0.81–2.7)	0.21	–	–
Educational status (GP 1)^1	1.5 (0.81–2.7)	0.20	–	–
Differences between estimated and  measured CRP (mg/L)^2	1.02 (1.01–1.03)	<0.001	1.03 (1.01–1.04)	<0.001
CRP crucial for treatment (yes 1)	2.6 (1.4–4.8)	0.0025	2.9 (1.5–5.5)	0.0016

1 General practitioner specialist group (GP group) and the group that visited non-specialists (non-specialist GP group, including residents in family medicine).

2 Difference between estimated and measured CRP in absolute values.

Statistically significant p-values are in bold (p<0.05).