# Diagnostic value of procalcitonin for identifying the etiology of lower respiratory tract infections: a systematic review and meta-analysis

## TL;DR

This study evaluates whether procalcitonin levels can help identify the cause of lower respiratory infections in adults.

## Contribution

The study provides a meta-analysis of procalcitonin's diagnostic accuracy for differentiating pathogens in lower respiratory tract infections.

## Key findings

- Procalcitonin has moderate accuracy in distinguishing bacteria from viruses in lower respiratory tract infections.
- Procalcitonin also shows moderate accuracy in differentiating typical from atypical pathogens.

## Abstract

Differentiating pathogens of lower respiratory tract infections(LRTIs) is challenging. This study aims to determine whether procalcitonin(PCT) level could distinguish different pathogens in adults with LRTIs.

We searched the PubMed, EMBASE, and the Cochrane Central Register of Controlled Trails that identified all relevant diagnostic accuracy studies. Studies were assessed for reporting of diagnostic accuracy, relevance and quality. Data were extracted for meta-analysis.

18 trials involving 3174 patients were included. For differentiating bacteria from viruses, pooled sensitivity, specificity, positive likelihood ratio(+LR), negative likelihood ratio(−LR) and diagnostic odds ratio(DOR) for PCT(0·5ug/L) were 0.49(95%CI, 0.33–0.66), 0.80(95%CI,0.65–0.90), 2.48(95%CI,1.75–3.50), 0.63 (95%CI, 0.52–0.77) and 3.93(95%CI,2.87–5.37), respectively. For differentiating typical pathogens from atypical pathogens, pooled sensitivity, specificity, +LR, -LR and DOR for PCT(0·5ug/L) were 0.60(95%CI,0.41–0.76), 0.81(95%CI,0.61–0.92), 3.09(95%CI,1.80–5.32), 0.50(95%CI,0.37–0.68) and 6.20(95%CI,3.76–10.21), respectively.

The results of this meta-analysis showed that PCT has moderate diagnostic accuracy for lower respiratory tract pathogens such as bacteria, viruses, and atypical pathogens.