June 21, 2007 — The US Preventive Services Task Force (USPSTF) has issued updated guidelines regarding screening for chlamydia infection and published their new recommendations and an accompanying evidence review online in the June 19 Clinical Guidelines/Position Papers Collection of the Annals of Internal Medicine and will appear in the July 17 print issue of journal. The updated guidelines are based on a small amount of new evidence, but there are still large evidence gaps regarding the ability of screening in men to improve health outcomes in women.
"Chlamydial infection is the most common sexually transmitted bacterial infection in the United States, with an estimated 3 million new cases annually," write David S. Meyers, MD, and colleagues from the Agency for Healthcare Research and Quality in Rockville, Maryland, in the evidence-based review. "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.... Although 75% of genital infections in women and 95% in men are asymptomatic, up to 40% of untreated cases of C. trachomatis infection in women progress to pelvic inflammatory disease (PID)."
In 2001, the USPSTF concluded that good evidence supports screening for chlamydial infection among asymptomatic women at increased risk for infection, including women at risk because of young age. However, it found less evidence regarding screening of pregnant women. Based on estimates of benefits and harms, the USPSTF recommended screening only for pregnant women at increased risk. At that time, there was a major gap in the evidence regarding the effectiveness of screening in men. The USPSTF therefore made no recommendation concerning men and concluded the evidence was insufficient.
To prepare for an update of the 2001 recommendations, the authors identified 452 English-language articles in PubMed between July 2000 and July 2005, they identified additional articles through bibliographic reviews and discussions with experts, and they summarized a systematic evidence review commissioned by the USPSTF. Explicit inclusion and exclusion criteria for each of 3 key questions were used to classify reviewed studies.
For studies of screening in nonpregnant women at increased risk, review was limited to randomized controlled trials, whereas for other groups both randomized controlled studies and nonrandomized, prospective, controlled studies were included. Using standardized forms, staff of the Agency for Healthcare Research and Quality abstracted data on study design, setting, sample, randomization, blinding, results, and harms.
Only 1 new poor-quality study met inclusion criteria. Findings from this study suggested that among nonpregnant women at increased risk, screening for chlamydial infection was associated with a lower prevalence of chlamydial infection and fewer reported cases of PID at 1-year follow-up. The reviewers found no new evidence on screening in pregnant women, nonpregnant women not at increased risk, or men.
"A systematic review found a small amount of new evidence to inform the USPSTF as it updates its recommendations regarding screening for chlamydial infection," the authors write. "There are large gaps in the evidence regarding the ability of screening in men to improve health outcomes in women."
An accompanying article provides the updated USPSTF recommendations about screening sexually active adolescents and adults for chlamydial infection.
"Chlamydial infection during pregnancy is related to adverse pregnancy outcomes, including miscarriage, premature rupture of membranes, preterm labor, low birth weight, and infant mortality," the guidelines note. "The USPSTF found fair evidence that nucleic acid amplification tests (NAATs) can identify chlamydial infection in asymptomatic men and women, including asymptomatic pregnant women, with high test specificity. In low prevalence populations, however, a positive test result is more likely to be false positive than true positive, even with the most accurate tests available."
For the updated guidelines, the USPSTF weighed the benefits (improved fertility, pregnancy outcomes, and infection transmission) and harms (anxiety, relationship problems, and unnecessary treatment of those with false-positive results) of chlamydial screening, based on their 2001 recommendations and the accompanying systematic review of English-language articles published between July 2000 and July 2005.
Their specific recommendations are as follows:
Screen for chlamydial infection in all sexually active nonpregnant young women aged 24 years or younger and in older nonpregnant women who are at increased risk (A level recommendation).
Screen for chlamydial infection in all pregnant women aged 24 years or younger and in older pregnant women who are at increased risk (B level recommendation).
Do not routinely screen for chlamydial infection in women age 25 years or older, regardless of pregnancy status, unless they are at increased risk (C level recommendation).
For men, current evidence is insufficient to evaluate the balance of benefits and harms of screening for chlamydial infection (I statement).
Other organizations recommending screening for chlamydia in women at increased risk for chlamydial infection are the American Academy of Family Physicians, the American College of Obstetricians and Gynecologists, the American College of Preventive Medicine, the Canadian Task Force on Preventive Health, and the US Centers for Disease Control and Prevention (CDC).
In addition, the American College of Preventive Medicine and the Canadian Task Force recommend screening all pregnant women, the American Academy of Family Physicians and the American College of Obstetricians and Gynecologists recommend screening pregnant women who are at increased risk for chlamydial infection, and the CDC recommends at least annual screening for chlamydia in men who have sexual intercourse with men.
The authors have disclosed no relevant financial relationships.
Ann Intern Med. 2007;147:128-141.
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