BACKGROUND:

The clinical value of antibiotic prophylaxis in preventing Lyme disease remains uncertain, owing to a meta-analysis lacking sufficient power to demonstrate efficacy and a more recent trial showing effectiveness but lacking precision. Our objective was to update our prior meta-analysis on antibiotic prophylaxis for the prevention of Lyme disease, to obtain a more precise estimate of treatment effect.

METHODS:

Clinical trials were identified by searching MEDLINE, Embase, the Cochrane Library and trial registries, and by an assessment of the bibliographies of retrieved articles and reviews. Trials were selected if their patients were randomly allocated to a treatment or placebo group within 72 h following an Ixodes tick bite and had no clinical evidence of Lyme disease at enrollment. Details of the trial design, patient characteristics, interventions and outcomes were extracted from each article. Study quality was assessed using the Jadad scale.

RESULTS:

Four placebo-controlled clinical trials were included for review. Among 1082 randomized subjects, the risk of Lyme disease in the placebo group was 2.2% [95% confidence interval (CI), 1.2%-3.9%] compared with 0.2% (95% CI, 0.0%-1.0%) in the antibiotic-treated group. Antibiotic prophylaxis significantly reduced the odds of developing Lyme disease compared with placebo (pooled odds ratio=0.084; 95% CI, 0.0020-0.57; P=0.0037).

CONCLUSIONS:

The available evidence to date supports the use of antibiotic prophylaxis for the prevention of Lyme disease in endemic areas following an Ixodes tick bite. Pooled data from four placebo-controlled trials suggests that one case of Lyme disease is prevented for about every 50 patients who are treated with antibiotics.