SAN DIEGO – Focusing routine screening for Chlamydia trachomatis infection on women younger than 25 years may be inappropriate in some states in which older women are at significant risk for infection, an analysis of data from 326,601 tests suggest.
The 2010 guidelines on STDs by the Centers for Disease Control and Prevention recommend routine annual screening for chlamydia in sexually active females younger than 25 years and selective screening in older nonpregnant women with increased risk for infection, such as those with new or multiple sexual partners (MMWR 2010;59 [No. RR-12]).
Sherry Boschert/IMNG Medical Media
Dr. Mark G. Martens
U.S. Preventive Services Task Force guidelines are similar, and recommend against routine screening in women aged 25 years or older unless they have risk factors for infection (Ann. Intern. Med. 2007;147:128-34).
Those guidelines emphasize age because infection rates drop off steeply after age 24 years, but chlamydia rates also vary significantly by region, race, and socioeconomic status, Dr. Mark G. Martens said at the annual meeting of the American College of Obstetricians and Gynecologists.
A retrospective analysis of routine screening tests sent to one microbiology laboratory found that seven states had infection rates of at least 2% in women aged 25 years and older, reported Dr. Martens of Jersey Shore University Medical Center, Neptune, N.J. and his associates.
Meanwhile, prevalence rates for females younger than 25 years were less than 2% in eight states (California, Connecticut, Idaho, Kansas, Maine, New Hampshire, North Carolina, and Washington) and Puerto Rico.
"Perhaps screening by age isn’t the best answer," he said. "Perhaps we should be screening women who are over 25 years of age in some states, but not in others." That may be difficult to do but warranted, he added.
Two percent of all the tests in the analysis were positive for C. trachomatis. The tests were submitted to Bio-Reference Laboratories from January 2010 through June 2011 from 40 states, Washington, and Puerto Rico. The patients tested consisted mainly of middle-class women seen in insured office practices.
Approximately 5% of the 105,921 tests in females under 25 years old were positive, compared with 1% of the 220,680 tests in older women. Those results are similar to findings from the studies on which the federal guidelines are based.
In women aged 25 years or older in the current study, at least 2% of tests were positive in Arkansas, Delaware, Minnesota, New Hampshire, New Mexico, Oregon, and Wisconsin – a rate twice as high as the 1% "cut-off" that federal guidelines used to decide against routine screening in this age group, Dr. Martens noted.
Positivity rates in those same states varied greatly for women younger than 25 years, ranging from 0% in New Hampshire to more than 11% in Arkansas.
The three states with the highest rates of C. trachomatis infection rates in females younger than 25 years were Arkansas (11.4% positive), Louisiana (10.5%) and Mississippi (10.5%).
Chlamydia is one of the most common sexually transmitted infections, with approximately 4 million U.S. cases per year. More than 50% of infected women are asymptomatic, with an ongoing reservoir for infection. If untreated, approximately 30% of infected women will develop pelvic inflammatory disease with upper genital tract involvement and serious sequelae such as chronic abdominal pain, ectopic pregnancy, and infertility. Recurrent and persistent chlamydia infections are common.
Dr. Martens has been a speaker and adviser for Bio-Reference Laboratories, which conducted the tests.