Volume 33, Number 3, May/June 2001
Among Teenagers Treated For Chlamydia, Two-Year Reinfection Rate Nears 20%
Nearly one in five teenage women who have had a chlamydial infection are reinfected within two years, according to an analysis of data from Washington State.1 Women aged 15-19 are four times as likely as 30-44-year-olds to develop one repeat infection and five times as likely to be reinfected at least twice. Furthermore, teenagers are less likely than older women to seek care from the same facility each time they have a chlamydial infection.
Chlamydia is the most common bacterial infection in the United States, and repeat infections increase the risk of long-term complications such as pelvic inflammatory disease, infertility and ectopic pregnancy. Therefore, factors leading to repeat infections need to be identified and addressed. To this end, analysts examined data from a population-based sexually transmitted disease (STD) registry in Washington, which provided information on 32,698 women aged 10-44 who were treated for an initial chlamydial infection during the years 1993-1998. They assessed the proportion of women with at least one repeat infection (defined as a urogenital or rectal infection that occurred at least 30 days after appropriate treatment for the initial infection) and used logistic regression models to analyze predictors of repeat infections.
Forty-eight percent of the women were younger than 20 when they were first infected, 62% were white and 47% lived in an urban setting. Not-for-profit and public clinics (mainly family planning, STD, reproductive health and jail clinics) were used by approximately 41% of the women. Screening detected 45% of initial infections; at least 36% of women had sought care because they were experiencing STD symptoms. Four percent also had gonorrhea or another STD at the time of their first chlamydia diagnosis.
During the follow-up period, which ranged from six months to six years, 15% of women had at least one repeat infection, and 3% had two or more (range, 2-8). The median time to first repeat infection was approximately 11 months. In initial analyses, age was the predominant factor in predicting repeat infections. The rate of repeat infection within one year was highest (16%) among 10-14-year-olds and second-highest (11%) among 15-19-year-olds. In all, 6% of women younger than 20 were reinfected within six months, 11% within one year and 17% within two years. By contrast, for those aged 20 and older, reinfection rates were 4-10% in the two years after treatment.
Several other characteristics appeared to be modestly associated with an increased risk of repeat infection: being black or American Indian, obtaining care from a facility other than a family planning clinic, seeking services because of symptoms of or exposure to an STD, having gonorrhea at the time of the initial diagnosis and having a long interval between infections. Women living in nonurban areas appeared to have a reduced risk of repeat infection.
Results of the multivariate analyses confirmed that age is the strongest predictor of repeat chlamydial infection. When length of follow-up and type of clinic were taken into account, 10-14-year-olds were six times as likely as women between the ages of 30 and 44 to have at least one repeat infection and 12 times as likely to develop two or more repeat infections (odds ratios, 6.3 and 11.6, respectively). Older teenagers also had considerably higher odds of repeat infection than women aged 30-44 (3.5-4.5). Odds were roughly doubled for women in their early 20s but were not significantly elevated for those aged 25-29.
Nonwhite women, women who were coinfected with gonorrhea and those who had visited their provider because of STD symptoms had modestly elevated odds of repeat infection (odds ratios, 1.2-2.0). Residents of rural areas were considerably less likely than city dwellers to acquire a repeat infection (0.3); odds were also significantly reduced for those living in areas classified as semirural (0.5) or semiurban (0.8).
The researchers also examined where women sought care for consecutive episodes of chlamydia. They found that only 36% had both their initial and their first repeat infection diagnosed at the same clinic, and only 50% received both diagnoses from the same type of provider. Adolescents had the lowest rates of continuous care. Only 29% of 10-14-year-olds and 33% of older teenagers visited the same clinic for care of their first two infections, compared with 39-51% of adults. Similarly, the proportions visiting the same type of provider ranged from less than half of teenagers to three-quarters of women aged 30-44.
The analysts point to two important issues that are highlighted by their findings. First, the significant number of repeat chlamydial infections in adolescents indicates a serious public health problem; the rate of repeat infection even among older women also is of concern. Second, since women seek treatment at different kinds of sites, follow-up and epidemiological evaluations of repeat infections may be difficult.
One strategy the researchers suggest for addressing these problems is increased screening for chlamydial infection. For teenagers, screening as often as every six months could be beneficial because of the high incidence of repeat infections within this time period; for older women who have been infected, annual screening may be advantageous. Counseling also may be effective in reducing subsequent infections, especially among adolescents with a previous STD. And because adolescent women may acquire a repeat infection from untreated partners, the analysts stress the need for ensuring that infected partners receive treatment before teenagers resume having intercourse. "For the risk of long-term sequelae to be reduced," the analysts conclude, "more frequent screening for chlamydia must be accompanied by enhanced efforts to prevent repeat chlamydial infection."--J. Tomarken
1. Xu F et al., Repeat Chlamydia trachomatis infection in women: analysis through a surveillance case registry in Washington State, 1993-1998, American Journal of Epidemiology, 2000, 152(12):1164-1170.