Sensitivity and specificity of procalcitonin in predicting bacterial infections in patients with renal impairment.
BACKGROUND
It is unclear whether procalcitonin is an accurate predictor of bacterial infections in patients with renal impairment, although it is used as a biomarker for early diagnosis of sepsis. We determined the sensitivity, specificity, positive and negative predictive values, accuracy and best predictive value of procalcitonin for predicting bacterial infection in adult patients with severe renal impairment.


METHODS
Retrospective study at a single-center community teaching hospital involving 473 patients, ages 18-65, with Modification of Diet in Renal Disease eGFR ≤30 ml/min per 1.73 m(2), admitted between January 2009 and June 2012, with 660 independent hospital visits. A positive or negative culture (blood or identifiable focus of infection) was paired to the highest procalcitonin result performed 48 hours before or after collecting the culture.


RESULTS
The sensitivity and specificity to predict bacterial infection, using a procalcitonin level threshold of 0.5 ng/mL, was 0.80 and 0.35 respectively. When isolating for presence of bacteremia, the sensitivity and specificity were 0.89 and 0.35 respectively. An equation adjusting for optimum thresholds of procalcitonin levels for predicting bacterial infection at different levels of eGFR had a sensitivity and specificity of 0.55 and 0.80 respectively.


CONCLUSIONS
Procalcitonin is not a reliably sensitive or specific predictor of bacterial infection in patients with renal impairment when using a single threshold. Perhaps two thresholds should be employed, where below the lower threshold (i.e. 0.5 ng/mL) bacterial infection is unlikely with a sensitivity of 0.80, and above the higher threshold (i.e. 3.2 ng/mL) bacterial infection is very likely with a specificity of 0.75.
Department of Medicine , Santa Barbara Cottage Hospital , California.
Dena
D
El-Sayed
Department of Research, Santa Barbara, California ; Santa Barbara Cottage Hospital , California.
Jonathan
J
Grotts
Santa Barbara Cottage Hospital , California ; Departments of Nephrology.
William A
WA
Golgert
Santa Barbara Cottage Hospital , California ; Infectious Diseases , Sansum Clinic , Santa Barbara, California.
Alan M
AM
Sugar
bacterial infections; procalcitonin; renal insufficiency; sensitivity; specificity