Table 3.

Association of procalcitonin and C-reactive protein with bacterial coinfection (N = 4076)

Variables	Adjusted OR (95% CI)a	p value
Model 1
Procalcitonin ≥ 0.12 ng/mLb	1.11 (0.69–1.79)	0.659
C-reactive protein ≥ 97 mg/Lb	2.00 (1.25–3.19)	0.004
Model 2
Procalcitonin ≥ 0.12 ng/mLb and C-reactive protein ≥ 97 mg/Lb	1.72 (1.15–2.56)	0.008

Mixed-effects models with center variable as a random effect. Data are shown as estimated ORs (95% CIs) of the explanatory variables in the bacterial coinfection group. The p value is based on the null hypothesis that all ORs relating to an explanatory variable equal unity (no effect). p values marked in bold indicate numbers that are statistically significant on the 95% confidence limit. Area under the ROC curve, AUC model 1 = 0.76 (95% CI 0.72 to 0.80); AUC model 2 = 0.76 (95% CI 0.71–0.80)

^aAdjusted for variables (age, sex, BMI, comorbidities, SOFA (without respiratory system component), PaO₂/FiO₂ ratio at hospital admission, leucocyte count ≥ 11 × 10⁹/L, septic shock and COVID-19 wave)

^bCut-off value obtained from ROC curve for bacterial coinfection (value with a sensitivity of 80%)