Sex Transm Infect 82:265 doi:10.1136/sti.2005.018978
  • Letter

Condom effectiveness for prevention of C trachomatis infection

  1. L Warner1,2,
  2. M Macaluso1,
  3. D Newman1,
  4. H Austin2,
  5. D Kleinbaum2,
  6. M Kamb3,
  7. J Douglas3,
  8. C K Malotte4,
  9. J M Zenilman5
  1. 1Centers for Disease Control and Prevention, Division of Reproductive Health, Atlanta, GA, USA
  2. 2Rollins School of Public Health of Emory University, Department of Epidemiology, Atlanta, GA, USA
  3. 3Centers for Disease Control and Prevention, Division of STD Prevention, Atlanta, GA, USA
  4. 4California State University – Long Beach Department of Health Science, Long Beach, CA, USA
  5. 5Baltimore City Health Department, and Johns Hopkins University School of Medicine, Infectious Diseases Division, Baltimore, MD, USA
  1. Correspondence to:
 Lee Warner
 Centers for Disease Control and Prevention, Division of Reproductive Health, 4770 Bulford Highway NE, Mail Stop K-34, Atlanta, GA 30333, USA; dlw7{at}
  • Accepted 17 November 2005

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 …