C-reactive protein influences the doctor’s degree of suspicion of pneumonia in primary care: a prospective observational study

Figures & data

Table 1. Characteristics of the study population.

	Number of patients (n = 265) n (%)	Median (Interquartile range)	Data missing n (%)
Male	131 (49.4)		0
Female	134 (50.6)
Age		53 (38;68)
CRP		37 (11;84)
Symptom duration		8 (6;14)	2
Smoking habits			6 (2.3)
Current smoker	23 (8.9)
Ex-smoker	44 (17.0)
Non-smoker	192 (74.1)
Antipyretics	105 (42.5)		18 (6.8)
Abnormal chest sounds	133 (50.8)		3 (1.1)
Examined by
General practitioner	164 (61.9)		1 (0.4)
Resident physician	53 (20.0)
Interns	47 (17.8)

Figure 1. Median CRP levels in the different degrees of suspicion after CRP testing (p < 0.001), Kruskal–Wallis test. Circles and asterisk represent outliers and extreme outliers, respectively (box and whisker plot).

Figure 2. Distribution and shift in degree of suspicion before and after the CRP results. The narrow bars, in the upper part, represent the shift in degree of suspicion.

Table 2. Propensity of any degree of suspicion of pneumonia after CRP testing.

	Adjusted logistic regression n = 231 (missing 34)
	p value	Odds ratio (95%CI)
Female	0.15	1.8 (0.81–4.2)
Age > 65 years	0.057	0.38 (0.14–1.07)
Symptom duration	0.39	1.0 (0.98–1.1)
Current smoker	0.73	1.3 (0.33–4.9)
Body temperature ≥ 38˚C	0.99	0.29 (0.29–3.4)
Abnormal chest sounds	<0.001	16 (6.4–38)
Intake of antipyretics	0.89	0.93 (0.39–2.2)
CRp ≥ 50 mg/L	<0.001	79 (19–335)

Nagelkerke R ² 0.571. Area under curve (AUC) 0.904.