Diagnostic value of procalcitonin for bacterial infection in elderly patients - a systemic review and meta-analysis

To summarise evidence for the diagnostic accuracy of procalcitonin (PCT) tests for identifying systemic bacterial infections in elderly patients.

Major databases, including MEDLINE, EMBASE and the Cochrane Library, were searched for studies published from 1975 to March 2013 that evaluated PCT as a marker for diagnosing systemic bacterial infections in elderly patients and that provided sufficient data to construct two-by-two tables.

Four studies were available for quantitative meta-analysis. The area under a summary receiver operating characteristic curve was 0.89 (95% CI: 0.86-0.92). The overall sensitivity and specificity estimates for PCT tests were 0.83 (95% CI: 0.38-0.98) and 0.83 (95% CI: 0.60-0.94), respectively. These studies reported heterogeneous sensitivity estimates ranging from 0.24 to 0.96. The positive likelihood ratio for PCT (LR+ = 4.77; 95% CI: 2.49-9.13) was not sufficiently high for its use as a rule-in diagnostic tool, while its negative likelihood ratio was acceptably low for its use as a rule-out diagnostic tool (LR- = 0.20; 95% CI: 0.04-0.97).

Existing data suggest that PCT tests may add to the diagnosis of sepsis in elderly patients. We did not observe the performance of the PCT test in elderly patients inferior to adult patients. Given the imperfect accuracy, we do not recommend that the PCT test be used in isolation; instead, we suggest that it be interpreted in the context of clinical findings.