Seven RCTs (n=624 patients) met the inclusion criteria. Three trials were described as double-blind and four were single-blind.
Catheter-related infection was 7.72 times lower with antimicrobial locking solutions compared with heparin locks (95% CI 5.1 to 10.3; seven trials, n=624 patients). Using absolute risk reduction, this translated to a number needed to treat (NNT) of three to prevent one catheter-related infection per 100 catheter-days. Catheter-related infection rates in heparin groups were similar across all studies (range 2.1 to 4.1 per 1,000 catheter-days). Catheter-related infection rates achieved with the different antimicrobial locking solutions were of similar magnitude. Statistical heterogeneity was not reported.
Gentamicin showed to be an effective antimicrobial locking solution in a pooling of both high and low doses of the drug (RR 11.8, 95 CI 8.4 to 15.3; three studies), but heterogeneity was high (I2=81.6%).
Only single studies were available for other antimicrobial locking solutions. There was significantly lower mortality from catheter-related infection in patients who used antimicrobial locking solutions (two studies). Of the five studies assessing exit-site infections, two found fewer infections in the antimicrobial locking solutions arm, two reported no difference between the antimicrobial locking solutions group and heparin group and one study observed no exit-site infection during the study.
Generally, rates of adverse events were low across the studies and rates of catheter thrombosis did not increase with antimicrobial locking solutions.