Abstract:
Background: Differential time to positivity (DTP), typically defined as pathogen growth at least two hours earlier from catheter vs paired peripheral blood cultures, is sometimes used to diagnose central line associated bloodstream infections (CLABSIs). Previous studies assessing DTP, however, have been small, provided conflicting results, and have not assessed heterogeneity across important subgroups.
Methods: We conducted a systematic review of the diagnostic characteristics of DTP for CLABSI, using MEDLINE, Embase, Web of Science, CINAHL, LILACS, AMED and the Cochrane database. Studies were eligible for inclusion if they reported sensitivities, specificities, predictive values, likelihood ratios, or 2×2 tables of DTP for diagnosing CLABSI. Extracted data were analyzed by creating forest plots, performing bivariate model meta-analysis, and assessing quality using QUADAS-2.
Results: Our search identified 274 records of which 23 met criteria for meta-analysis. Among 2,526 suspected CLABSIs, DTP demonstrated a summary sensitivity of 81.3% (95% CI 72.8-87.7%), specificity of 91.8% (95% CI 84.5-95.8%), positive likelihood ratio of 9.89 (95% CI 5.14-19.00), and negative likelihood ratio of 0.20 (95% CI 0.14-0.30). Covariate analysis based on catheter duration, study design, and patient immune status demonstrated no significant differences. However, DTP performed worse for Staphylococcus aureus (low sensitivity but high specificity) and Candida (high sensitivity but low specificity) compared to other organisms.
Conclusion: DTP performs well in ruling CLABSIs in or out. Obtaining paired catheter and peripheral blood cultures for DTP when the infectious source is unclear may prevent unnecessary line removal and diagnostic tests, although this needs to be balanced against potentially higher contamination rates from catheter cultures.
Reference:Dhaliwal M, Daneman N. Utility of Differential Time to Positivity in Diagnosing Central Line Associated Bloodstream Infections: A Systematic Review and Meta-Analysis. Clin Infect Dis. 2023 Apr 17:ciad225. doi: 10.1093/cid/ciad225. Epub ahead of print. PMID: 37062596.