The objective of the systematic review and meta-analysis published in the latest issue of Influenza and other Respiratory Viruses was to summarize the available data on the accuracy of the use of the levels of procalcitonin to identify secondary bacterial infections that have developed in patients with influenza.

The search for the relevant studies was carried out in all the main medical databases (MEDLINE, EMBASE, Cochrane Library) for the period from January 1966 to May 2009. The meta-analysis included studies in which the determination of procalcitonin was considered as a marker for the diagnosis of bacterial infection in flu patients. Sufficient data should be provided in the studies to construct four-cell contingency tables.

A total of 6 studies were identified, which described 137 cases of bacterial co-infection and 281 cases without concomitant bacterial infection. The total area under the ROC curve was 0.68 (95% confidence interval 0.64-0.72). The overall sensitivity and specificity for the determination of procalcitonin were 0.84 (95% CI 0.75-0.9) and 0.64 (95% CI 0.58-0.69), respectively. The studies included in the meta-analysis showed quite heterogeneous sensitivity indicators, which ranged from 0.74 to 1.0. The positive likelihood ratio for the determination of procalcitonin (LR + = 2.31; 95% CI 1.93-2.78) was not high enough to be used as a confirmatory diagnostic test, while the negative likelihood ratio was very low, which does not exclude the possibility of its use as an exclusive diagnostic test (LR- = 0.26; 95% CI 0.17-0.40).

Thus, despite the fact that the procalcitonin test is characterized by a high sensitivity (especially in patients in the intensive care unit and intensive care units), the results of this meta-analysis suggest that in patients with secondary bacterial infection developed in the context of influenza, the specificity of this diagnostic marker is low. Due to the suboptimal value of the positive likelihood ratio and a good indicator of the negative likelihood ratio, this test can be used as an acceptable diagnostic marker to exclude the diagnosis of secondary bacterial infection in patients with influenza , but the determination of procalcitonin cannot be used as the only independent diagnostic marker to confirm the diagnosis of secondary bacterial infection. infections.