Clinico-bacterial and prognostic factors in patients with suspected blood stream infection and elevated serum procalcitonin levels

Abstract

This study determined prognostic factors by comparing clinico-bacterial factors based on significant elevated serum procalcitonin levels in patients with suspected bloodstream infection (BSI). We retrospectively analyzed the medical records of 1,052 patients (age ≥16 years) with fever (temperature ≥38°C) and serum procalcitonin levels of ≥2.0 ng/mL, and blood culture results. The optimal cutoff value of the significant elevation of procalcitonin was determined using the minimum P-value approach. Clinico-bacterial factors were analyzed per the procalcitonin levels, and significant independent factors for short-term survival were investigated in 445 patients with BSI. Patients with suspected BSI were aged, on average, 72.3 ± 15.1 years, and the incidence of positive blood culture was 42.3%; and the 14-day survival was 83.4%. Procalcitonin ≥100 ng/mL was the most significant predictor for survival. Multivariate analysis in patients with suspected BSI showed that estimated glomerular filtration rate (eGFR) <30 mL/min/1.73 m² and procalcitonin ≥100 ng/mL were significant independent unfavorable prognostic factors. Microorganisms were similar between patients with procalcitonin level 2-99 ng/mL (n=359) and those with ≥100 ng/mL (n=86). Multivariate analysis in patients with BSI showed that eGFR <30 mL/min/1.73 m², procalcitonin ≥100 ng/mL, and primary infectious foci were significant independent prognostic factors. Patients with foci in the gastrointestinal tract and respiratory system had unfavorable 14-day survival. In conclusions, eGFR <30 mL/min/1.73 m² and procalcitonin ≥100 ng/mL were significant independent unfavorable prognostic factors for suspected BSI. Primary infectious foci (gastrointestinal tract and respiratory system) were associated with unfavorable short-term survival in patients with positive blood culture.

Keywords: blood culture; bloodstream infection; procalcitonin; renal function; survival.

Fig. 1

Number of patients, incidence of positive blood culture, and 14-day survival in eleven ranges of procalcitonin levels The incidence of positive blood culture and 14-day survival were significantly related to procalcitonin level (p<0.0001 and p=0.0259, respectively); the more the procalcitonin level was elevated, the higher was the incidence of positive blood culture and the lower was the 14-day survival.

Fig. 2

Fourteen day survival and the p-value of differences classified by 10 cutoff values Boxes indicate the 14-day survival of patients with each procalcitonin level classified by cutoff values of 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 ng/mL. Fourteen-day survival was significantly different in terms of cutoff values between 30 and 100 ng/mL. The p-value of differences in 14-day survival was lowest between patients with procalcitonin 2–100 ng/mL and those with ≥100 ng/mL (85.1% and 71.7%, p=0.0000429), and the 14-day survival was lowest in patients with procalcitonin ≥100 ng/mL.

Fig. 3

Short-term survival according to the serum procalcitonin levels (a) 1052 patients with suspected blood stream infection, (b) 445 patients with positive blood culture.

Fig. 4

Short-term survival according to the primary infectious foci causing bacteremia in 445 patients with positive blood culture Green: biliary tract Blue: urinary tract Red: abdominal cavity Black: respiratory system Brown: gastrointestinal tract