Screening for chlamydial infection

Objectives: To examine data on the effectiveness of screening for chlamydia l infection by a physician or other health care professional. Specifically, we examine the evidence that early treatment of chlamydial infection impro ves health outcomes, as well as evidence of the effectiveness of screening strategics in nonpregnant women, pregnant women, and men, and the accuracy of tests used for screening. This review updates the literature since the l ast recommendation of the U.S. Preventive Services Task Force published in 1996. Search Strategy: We searched the topic of chlamydia in the MEDLINE, HealthS TAR, and Cochrane Library databases from January 1994 to July 2000, supplem ented by reference lists of relevant articles and from experts in the field .,Articles published prior to 1994 and research abstracts were cited if par ticularly important to the key questions or to the interpretation of includ ed articles. Selection Criteria: A single reader reviewed all English abstracts. Article s were selected for full review if they were about Chlamydia trachomatis ge nitourinary infections ill nonpregnant women, pregnant women, or men and we re relevant to key questions in the analytic framework. Investigators read the full-text version of the retrieved articles and applied additional elig ibility criteria. For all topics, we excluded articles if the!: did not pro vide sufficient information to determine the methods for selecting subjects and for analyzing data. Data Collection and Analysis: We systematically reviewed three types of stu dies about screening in nonpregnant women that relate to three key question s: (1) studies about the effectiveness of screening programs in reducing pr evalence rates of infection, (2) studies about risk factors for chlamydial infection in women, and (3) studies about chlamydial screening tests in wom en. Our search found too few studies on pregnant women to systematically re view, although pertinent studies are described. We systematically reviewed two types of studies about screening in men: (1) studies about prevalence r ates and risk factors for chlamydial infection in men and (2) studies about chlamydial screening tests in men. Main Results: Nonpregnant women. The results of a randomized controlled tri al conducted in a large health maintenance organization indicate that scree ning women selected by a set of risk factors reduces the incidence of pelvi c inflammatory disease (PID) over a 1-year period. Changes in population pr evalence rates have not been well documented because few studies have emplo yed a representative population sample. Age continues to be the best predic tor of chlamydial infection in women, with most studies evaluating cut-offs at age younger than 25 years. Other risk factors may be useful predictors, but these are likely to be population specific. To determine the accuracy of screening tests for women, we retrieved and critically reviewed 34 artic les on test performance. Results indicate that endocervical swab specimens and first-void urine specimens have similar performance when using DNA ampl ification tests and have better sensitivity than endocervical culture. Recu rrent chlamydial infections in women have been associated with increased ri sks for PID and ectopic pregnancies. Pregnant women. The Second Task Force recommendations for screening pregnan t women were based on two major studies demonstrating improved pregnancy ou tcomes following treatment of chlamydial infection. We identified no recent studies on this topic in our literature search. Very few studies describe risk factors for chlamydial infection in pregnant women. Nonculture testing techniques appear to perform well in pregnant women, although studies are limited. Men. No studies described the effectiveness of screening or early treatment for men in reducing transmission to women or in preventing acute infection s or complications in men. Studies of prevalence rates and risk factors for chlamydial infection in men are limited. Age lower than 25 years is the st rongest known risk factor cited so far. Results of urethral swab specimens compared to first-void urine specimens were similar for DNA amplification t ests. DNA amplification techniques are more sensitive than culture. Conclusions: Screening women for Chlamydia trachomatis reduces the incidenc e of PID, and it is associated with reductions in prevalence of infection i n uncontrolled studies. No studies were found to determine whether screenin g asymptomatic men would reduce transmission or prevent acute infections or complications. Age is the strongest risk factor for men and women. A varie ty of tests can detect chlamydial infection with acceptable sensitivity and specificity, including new DNA amplification tests that use either endocer vical swabs in women, urethral swabs ill men, or first-void urine specimens from men and women.