Research article
Uptake of Regular Chlamydia Testing by U.S. Women: A Longitudinal Study

https://doi.org/10.1016/j.amepre.2010.05.011Get rights and content

Background

Routine chlamydia screening is a recommended preventive intervention for sexually active women aged ≤25 years in the U.S. but rates of regular uptake are not known.

Purpose

This study aimed to examine rates of annual chlamydia testing and factors associated with repeat testing in a population of U.S. women.

Methods

Women aged 15–25 years at any time from January 1, 2002, to December 31, 2006 who were enrolled in 130 commercial health plans were included. Data relating to chlamydia tests were analyzed in 2009. Chlamydia testing rates (per 100 woman-years) by age and rates of repeated annual testing were estimated. Poisson regression was used to examine the effects of age and previous testing on further chlamydia testing within the observation period.

Results

In total, 2,632,365 women were included. The chlamydia testing rate over the whole study period was 13.6 per 100 woman years after adjusting for age-specific sexual activity; 8.5 (95% CI=6.0, 12.3) per 100 woman-years in those aged 15 years; and 17.7 (95% CI=17.1, 18.9) in those aged 25 years. Among women enrolled for the entire 5-year study period, 25.9% had at least one test but only 0.1% had a chlamydia test every year. Women tested more than once and older women were more likely to be tested again in the observation period.

Conclusions

The low rates of regular annual chlamydia testing do not comply with national recommendations and would not be expected to have a major impact on the control of chlamydia infection at the population level.

Introduction

Annual screening for Chlamydia trachomatis (chlamydia) is recommended by the CDC for all sexually active women aged ≤25 years1 and for women and men aged 15–25 years by the Royal Australian College of General Practitioners.2 In England, screening is recommended annually and after a change of sexual partner for women and men.3 As stated by the U.S. Preventive Services Task Force, however, the optimal screening interval is not known.4

Chlamydia is the most commonly reported infection in the U.S., with more than 1 million cases notified each year.5 Transmission continues because most infections are asymptomatic,6 the duration of untreated infection is long,7 and young adults change sexual partners frequently.8 Chlamydia infections that ascend to the upper genital tract can cause pelvic inflammatory disease (PID); ectopic pregnancy; and infertility.9 The aims of screening are therefore to detect and treat asymptomatic infection and reduce the incidence of PID.1, 4 Mathematical modeling studies differ in their assumptions but generally assume that all10 or a substantial fixed proportion in the range 35%–65% of women in the target age group receives testing every year.11, 12, 13, 14, 15

The proportion of women who have repeated chlamydia tests every year is not known. Coverage of chlamydia screening is, however, one of the indicators used by U.S. health insurance plans to evaluate the quality of healthcare services (http://www.ncqa.org/).16 The Healthcare Effectiveness Data and Information Set (HEDIS) indicator for chlamydia screening is calculated each year and measures the proportion of women documented as being sexually active, based on use of specific health services and who had a chlamydia test within the past 12 months.17 In 2007 the HEDIS estimate of chlamydia screening coverage was 36% for women aged 16–20 years in commercial health plans.16 Cross-sectional analysis does not show whether the same women are screened every year or if different women are being screened irregularly. Longitudinal analyses of repeated uptake at the enrollee level of preventive services would therefore be useful, and electronic medical records provide an accessible source of data.18 The objective of this study was to determine rates of annual chlamydia testing, as recommended by the CDC, in a cohort of women enrolled in U.S. commercial health plans.

Section snippets

Cohort Construction

The 2002 to 2006 MarketScan databases were used to construct a cohort. The database includes de-identified person-specific data from people enrolled in more than 130 commercial health plans serving more than 100 large employers in all four regions (South, North-Central, West, and Northeast) of the U.S. (http://www.medstat.com/). A unique enrollee identifier is assigned to each individual in the MarketScan claims database by encrypting information provided by data contributors. All women aged

Results

There were 2,632,365 women aged 15–25 years with a continuous period of enrollment of at least 2 days between January 1, 2002, and December 31, 2006 (total follow-up=4,115,444 years, M=1.5 years, SD=1.2; Table 2). The number of women in the cohort increased from 563,926 in 2002 to 989,677 in 2004 and 1,261,082 in 2006. Of all women, 1,985,920 (75.4%) had at least one recorded encounter with a health service. In this group, 321,004 women had 415,072 chlamydia tests. The number of tests increased

Discussion

Among women aged 15–25 years enrolled in commercial health plans from 2002 to 2006, the rate of chlamydia testing overall was 13.6 per 100 woman-years after adjusting the denominator for sexual activity according to the 2002 NSFG. Chlamydia testing rates were lowest in the youngest women. Annual testing rates were low; only 0.1% of women with 5 full years of enrollment were tested in each year, and 74.1% were never tested. Estimated rates of chlamydia testing using the HEDIS measure were

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