Azithromycin versus doxycycline for the treatment of genital chlamydia infection: a meta-analysis of randomized controlled trials

There has been recent debate questioning the efficacy of azithromycin for the treatment of urogenital chlamydia infection. We conducted a meta-analysis to compare the efficacy of 1 g azithromycin with 100 mg doxycycline twice daily (7 days) for the treatment of urogenital chlamydia infection.

Medline, PubMed, Embase, Cochrane Controlled Trials Register, Cochrane reviews, and Cumulative Index to Nursing and Allied Health Literature were searched until 31 December 2013. Randomized controlled trials comparing azithromycin with doxycycline for the treatment of genital chlamydia with evaluation of microbiological cure within 3 months of treatment were included. Sex, diagnostic test, follow-up time, attrition, patient symptomatic status, and microbiological cure were extracted. The primary outcome was the difference in efficacy at final follow-up. Study bias was quantitatively and qualitatively summarized.

Twenty-three studies were included evaluating 1147 and 912 patients for azithromycin and doxycycline, respectively. We found a pooled efficacy difference in favor of doxycycline of 1.5% (95% confidence interval [CI], -.1% to 3.1%; I(2) = 1.9%; P = .435; random effects) to 2.6% (95% CI, .5%-4.7%; fixed effects). Subgroup analyses showed that the fixed effects pooled efficacy difference for symptomatic men was 7.4% (95% CI, 2.0%-12.9%), and the random effects was 5.5% (95% CI, -1.4% to 12.4%).

There may be a small increased efficacy of up to 3% for doxycycline compared with azithromycin for the treatment of urogenital chlamydia and about 7% increased efficacy for doxycycline for the treatment of symptomatic urethral infection in men. However, the quality of the evidence varies considerably, with few double-blind placebo-controlled trials conducted. Given increasing concern about potential azithromycin failure, further well-designed and statistically powered double-blind, placebo-controlled trials are needed.