Condom effectiveness for prevention of C trachomatis infection

Replicating methods and comparing results across studies are critical for the resolution of scientific controversies. In a recent report, Niccolai et al demonstrated that condoms were effective in preventing chlamydia among STD clinic patients with known exposure to Chlamydia trachomatis .1 We were pleased to see the authors apply the methodology that we first presented for estimating condom effectiveness against chlamydia and gonorrhoea in 20012,3 and published in the American Journal of Epidemiology last year.4 Their findings confirm the importance of restricting the study population to people with known STI exposure (that is, sexual contacts of infected people) to reduce confounding on condom effectiveness estimates …