Chlamydia Screening Programs Don't Work: Expert

Mar. 23 --

THURSDAY, April 5 (HealthDay News) -- Population-wide screening programs for chlamydia, the most commonly reported sexually transmitted disease, may not actually work, a Swiss expert contends.

That's especially true for so-called "opportunistic" programs, which routinely test patients for chlamydia whenever they seek medical care.

"We do not have sufficient evidence that this approach to a screening program does more good than harm at reasonable cost," said Dr. Nicola Low, an epidemiologist at the University of Bern.

But despite that, and despite increasing rates of infection in nations that have screening programs, more countries continue to adopt this approach, Low wrote in an article appearing in this week's British Medical Journal.

U.S. social health experts took a neutral tone when discussing the report.

"We support current guidelines from the Centers for Disease Control and Prevention, which recommend annual chlamydia screening for sexually active females ages 25 and younger as well as older women at risk for this disease," said Fred Wyand, a spokesman for the American Social Health Association in Research Triangle Park, N.C.

"We believe it's especially important for women to be tested for chlamydia, since the infection is often asymptomatic, but if undetected and untreated can lead to serious health complications, such as pelvic inflammatory disease and infertility," Wyand added. "We are also in favor of discussion and research to determine which approaches to screening are most effective, in terms of both cost and in reducing the incidence of chlamydia infection."

Infection with the Chlamydia trachomatis pathogen is the most common preventable cause of pelvic inflammatory disease (PID) in young women. PID, in turn, can lead to ectopic pregnancy and infertility.

Chlamydia infection, which usually causes no symptoms, is easily treated, often with a single dose of antibiotics. Detection is also easy, with a urine-sample test; results are generally available within a day.

But recent evidence is emerging to suggest that chlamydia may result in fewer severe complications that previously thought. Chlamydia is currently the only sexually transmitted infection for which population screening has been implemented, stated a BMJ editorial.

Two types of screening programs exist. Proactive screening involves using population registries to invite people to be screened for a particular infection at regular intervals. Opportunistic screening targets people using health services for other reasons.

Chlamydia screening is currently recommended in Sweden, the United States and Canada, according to the BMJ report. An opportunistic screening program for all sexually active women and men under 25 years of age, the National Chlamydia Screening Programme, is scheduled to start in England in 2008.

But the evidence for such programs is weak, Low said.

In Sweden, a drop in chlamydia rates in the mid-1990s was attributed to widespread testing, but, in fact, the fall in rates coincided with a national campaign to prevent a more dangerous pathogen, HIV. Since 1995, chlamydia infection rates have been rising again in Sweden.

Similarly, in the United States, decreases in rates of chlamydia infection have been attributed to opportunistic screening programs.

Yet no randomized, controlled trial has shown that screening reduces long-term complications from chlamydia. And studies that do show a value have not been well-designed, while tending to overestimate the cost-effectiveness of the screening programs, Low noted.

Low argued that a consistent definition of "screening program" is needed and that screening programs for all diseases should be standardized.

"There is a difference between 'screening' and a 'screening program,' " Low said. "Any benefits of screening in a population will only be achieved if screening is implemented as a program. This means regular repeated screening of all those in the target population. Opportunistic screening as usually practiced does not ensure that people who have been screened once are invited for subsequent screening tests."

The bottom line, according to the Swiss expert: "Low overall coverage and infrequent screening will not control the spread of an asymptomatic, infectious disease."

There also needs to be more research to determine if screening programs really are effective, especially the more targeted, proactive kind, Low said. "There are trials of proactive chlamydia screening showing a benefit after one round of screening," she said. "The sustainability and duration of benefit of this approach to screening are therefore unknown."

Any screening program shouldn't replace prevention, another expert stressed.

"Prevention is really the best way to go, and sexually transmitted diseases are no exception to that rule," said Dr. Patricia Sulak, professor of obstetrics and gynecology at Texas A&M Health Science Center College of Medicine and an ob/gyn at Scott & White Hospital in Temple, Texas.

"Really, the best way for us to reduce problems is to look at the source of the problems, and that's multiple sexual partners," she said. "The earlier you start having sex, the greater the chance of becoming infected. We want to make sure we get prevention across."

More information

For more on chlamydia, visit the U.S. Centers for Disease Control and Prevention.

SOURCES: Nicola Low, M.D., reader, epidemiology and public health, department of social and preventive medicine, University of Bern, Switzerland; Fred Wyand, spokesman, American Social Health Association, Research Triangle Park, N.C.; Patricia Sulak, M.D., professor, obstetrics and gynecology, Texas A&M Health Science Center College of Medicine and ob/gyn, Scott & White Hospital, Temple, Texas; April 7, 2007, British Medical Journal