Table 7.

Representation of the heterogeneity of results and methodology of a selection of recent studies on the usefulness of time to blood culture positivity as a predictor of severity.

Reference	Country	Type of study	Result	Comment
Hsieh [131]	Multinational	Meta-analysis	A short TTP was associated with higher mortality and septic shock in some bacterial species, but not in Candida spp.	- Notable biases, presence of heterogeneity, mixing of pediatric and adult populations, important confounding factors not assessed, meta-regression analysis not significant.
Hamilton [138]	United Kingdom	Prospective multicenter cohort study.	TTP not associated with mortality except in Candida spp. (elevated TTP) and possibly in streptococci.	- More methodological soundness than most studies (includes time to incubation). - Limitations: does not assess time to effective treatment, small samples in some groups.
Siméon [143],	France	Prospective multicenter cohort study.	A short TTP is related to mortality and to the presence of endocarditis in S. aureus bacteremia.	- Some limitations: small sample, blood culture systems used, does not analyze blood culture volume.
Kim [139]	Canada	Retrospective study	Elevated TTP is associated with mortality in S. aureus bacteremia.	- Some limitations: retrospective, does not have detailed clinical information, does not analyze foci of infection, does not analyze antibiotic treatment.
Oldberg [144]	Sweden	Retrospective observational study	No association was observed between TTP with mortality or the presence of endocarditis in E. faecalis bacteremia.	- Some limitations: retrospective study, transesophageal echocardiogram not performed in all patients, does not include patients under treatment, does not analyze blood culture volume.

TTP: time to positivity