Twelve studies (137,392 participants) were included: one randomised controlled trial, 10 controlled interrupted times series and one cluster non-randomised controlled trial. Most studies were quasi-experimental and made little or no assessment of confounding factors. Only one study reported allocation concealment. Four studies assessed comparability between treatment groups.
Chlorhexidine reduced the chance of developing a bloodstream infection compared with control (OR 0.44, 95% CI 0.33 to 0.59; 12 studies; Ι²=58%). Results were similar for the subgroup analysis of bathing (five studies) compared with wipes (seven studies) and heterogeneity remained at a moderate level so was not explained by the type of chlorhexidine administration. Sensitivity analysis did not reveal any studies with influential results.
Six studies reported on adverse events but five did not report details for the control group. Event rates ranged from one to six participants who received chlorhexidine and were mostly rashes, dryness and skin allergies. Two studies reported crude mortality and overall death rates were 15.9% for chlorhexidine and 19.8% for control with no significant difference between groups.