Screening for chlamydial infection: an evidence update for the U.S. Preventive Services Task Force.

Background: Chlamydial infection is the most common sexually transmitted bacterial infection in the United States, with an estimated 3 million new cases annually. In 2001, the U.S. Preventive Services Task Force (USPSTF) recommended that clinicians screen all sexually active women at increased risk for infection for Chlamydia trachomatis.

Purpose: To summarize a systematic evidence review commissioned by the USPSTF in preparation for an update of its 2001 recommendation.

Data Sources: English-language articles identified in PubMed between July 2000 and July 2005. Additional articles were identified by bibliographic reviews and discussions with experts. A total of 452 articles were identified.

Study Selection: Explicit inclusion and exclusion criteria were used for each of 3 key questions. For studies of screening in nonpregnant women at increased risk, review was limited to randomized, controlled trials. For other groups, both randomized, controlled studies and nonrandomized, prospective, controlled studies were included.

Data Abstraction: Using standardized forms, staff of the Agency for Healthcare Research and Quality abstracted data on study design, setting, sample, randomization, blinding, results, and harms.

Data Synthesis: Only 1 new study met inclusion criteria. This poor-quality study of the effectiveness of screening for chlamydial infection among nonpregnant women at increased risk found that screening was associated with a lower prevalence of chlamydial infection and fewer reported cases of pelvic inflammatory disease at 1-year follow-up.

Limitations: No new evidence was found on screening in pregnant women, nonpregnant women not at increased risk, or men.

Conclusions: A systematic review found a small amount of new evidence to inform the USPSTF as it updates its recommendations regarding screening for chlamydial infection. There are large gaps in the evidence about screening men to improve health outcomes in women.