Introduction There has been considerable debate questioning the efficacy of azithromycin for the treatment of genital chlamydia. We conducted a meta-analysis to compare the efficacy of 1 gramme azithromycin with 100mg doxycycline twice daily for seven days for the treatment of genital chlamydia infection.

Methods Medline, PubMed, Embase and the Cochrane Controlled Trials Register were searched till end 2012. Inclusion criteria included (1) randomised controlled trial of azithromycin versus doxycycline for the treatment of urethral or cervical chlamydia, and; (2) evaluation of microbial cure within 3 months of treatment. Type of diagnostic test, duration of follow up, gender, patient status (all symptomatic versus both symptomatic/asymptomatic) and microbial cure were extracted. The primary outcome was difference in efficacy (doxycycline efficacy minus azithromycin efficacy) at final follow up. Meta-analysis calculated a pooled efficacy for each treatment and the difference in efficacy between treatments.

Results Of 692 references identified, 23 trials met the inclusion criteria. 1065 individuals were treated with azithromycin and 850 with doxycycline; all studies reported efficacy within 6 weeks follow-up. Pooled cure rates were 96.2%(95% CI: 94.2%, 98.3%) for azithromycin and 98.1%(95% CI: 96.6%, 99.7%) for doxycycline. The pooled efficacy difference was 1.9%(95% CI: 0.4%, 3.4%) showing a small but significant difference in favour of doxycycline; there was negligible heterogeneity between studies (I2 = 1.9%, p = 0.44). There was no difference in efficacy in men (3.8%; 95% CI:-1.2%, 8.8%) or women (–0.9%; 95% CI: –5.3%, 3.6%). When stratified by type of test, efficacy was significantly higher for doxycycline in culture-based studies (1.8%; 95% CI: 0.4%, 3.3%), but not in NAAT-based studies (5.5%; 95% CI: –2.1%, 13.1%). Efficacy was higher for doxycycline in symptomatic men (6.3%; 95% CI: 3.0%, 12.3%), but not in symptomatic women (–4.5%; 95% CI: –14.9%, 5.9%).

Conclusion These results suggest that doxycycline may be more effective than azithromycin for the treatment of urethral or cervical chlamydia infection, especially in symptomatic men.