Secondary Logo

Journal Logo


Chlamydia Screening of Young Sexually Active, Medicaid-Insured Women by Race and Ethnicity, 2002–2005

Christiansen-Lindquist, Lauren BA*†; Tao, Guoyu PHD; Hoover, Karen MD, MPH; Frank, Robbie BA; Kent, Charlotte PHD

Author Information
doi: 10.1097/OLQ.0b013e3181ab481b
  • Free

Chlamydia is the most prevalent bacterial sexually transmitted disease in the United States with approximately 1.1 million cases reported to the Centers for Disease Control and Prevention in 2007.1 Because chlamydial infections are usually asymptomatic, several national health organizations recommend annual chlamydia screening for sexually active women aged 25 years and younger.2–4

Different populations of women are disproportionately burdened by chlamydia. Young women have higher rates of chlamydia than older women, as do women in some racial and ethnic populations.1 Chlamydia rates are highest for women aged 15 to 24 years and are significantly higher among non-Hispanic black and Hispanic women (1398 and 473 cases per 100,000 in 2007, respectively) compared with non-Hispanic white women (162 cases per 100,000 in 2007).1 Women with Medicaid insurance, compared with women with private insurance, have higher rates of chlamydia.1,5 The Medicaid program provides medical insurance coverage for low-income persons that is funded by state and federal governments.6

As interventions and policies are developed to increase chlamydia screening, their effectiveness needs to be monitored. Thus, it is important that we are able to track trends in chlamydia screening over time, by age, and by race and ethnicity. The Healthcare Effectiveness Data and Information Set (HEDIS) is a tool used by 90% of US health plans to evaluate the quality of health care services.7 HEDIS measures indicate that the overall annual chlamydia screening for women aged 16 to 20 years with Medicaid insurance increased from 41% in 2002 to 50% in 2006. A limitation of this method is that HEDIS does not track chlamydia screening by race or ethnicity or the health care settings in which claims of chlamydia tests were submitted. National health care survey data have been used to estimate chlamydia screening rates of women at physician office and outpatient clinic visits by race and ethnicity and by insurance type.8,9 Because of small sample sizes, subgroup analyses of screening by race and insurance status are not possible. A recent study showed that women with Medicaid insurance were significantly more likely to report receiving a chlamydia test in the last 12 months compared with women with private or no insurance.10 Although this data provide insight into screening by insurance type, it is based on self report and also cannot be used to monitor trends over time because it was a 2002 cross-sectional analysis of a cohort study that enrolled middle and high school students in 1994. The objective of this study was to estimate annual chlamydia screening rates by race and ethnicity and by age for sexually active, Medicaid-insured women aged 15 to 21 years, and to monitor trends over time, from 2002 to 2005. Additionally, we studied the health care settings in which chlamydia test claims were submitted to identify potential venues for targeting interventions to increase screening.


We analyzed Medicaid child claims data from the MarketScan database for each year from 2002 to 2005 (MarketScan Database, Thomson Reuters [Healthcare] Inc, Ann Arbor, MI). More than 200 US commercial health plans are included in the MarketScan database, which includes person-specific information on enrollment and utilization of inpatient, outpatient, prescription drug, and carve-out services.11 The database also includes information on Medicaid claims from 8 US states. Because MarketScan data are deidentified and do not involve human subjects, Institutional Review Board review is not required. The Medicaid child claims data used in this study included length of patient enrollment, patient demographics, provider specialty, service provision dates, diagnostic codes (International Classification of Disease-Ninth Revision [ICD-9]), and procedural codes (Physician’s Current Procedural Terminology [CPT]) for patients aged 21 years and younger from those 8 unidentified US states. Because of confidentiality agreements between health plans and MarketScan, geographic identifying information (including region or state) was not available to us.

Our study population consisted of Medicaid-insured women aged 15 to 21 years who were enrolled in Medicaid for at least 330 days and had at least one medical service claim during the year of analysis. Using a method similar to that used to calculate the HEDIS measure of chlamydia screening, women were classified as sexually active if they had any claim for a sexual health service.7 A woman was classified as sexually active if, during the year of analysis, she had any ICD-9 or CPT code associated with the following: a Pap test or pelvic examination, a pregnancy-related service, a contraceptive service, or an sexually transmitted disease-related service. We estimated the proportion of sexually active women who were screened for chlamydia using the CPT chlamydia testing codes used for the HEDIS measure of chlamydia screening.7 We also calculated odds ratios for the comparison of screening rates among racial and ethnic groups and age groups.

χ2 tests were used to detect statistically significant differences in chlamydia screening rates of sexually active women by race and ethnicity and by age for each year. Mantel-Haenszel tests were used to detect statistically significant trends in chlamydia screening rates of sexually active women by year and by age, stratified by race and ethnicity. Significant findings were defined a priori as those with a P <0.05.


Our study population ranged from 90,900 women in 2002 to 173,400 women in 2005. The proportion of women identified as sexually active for 2002 to 2005 was 57%, 59%, 58%, and 57%, respectively (Table 1). Sexual activity varied significantly by race and ethnicity and by age. The proportion of sexually active women who were screened for chlamydia increased significantly (P <0.001) from 34% in 2002 to 44% in 2005 (Table 1, Fig. 1). Chlamydia screening rates also varied significantly by race and ethnicity and by age. Black women were significantly more likely to be screened for chlamydia than white women in all years (e.g., 51% vs. 39% in 2005, P <0.001). Sexually active women aged 19 to 21 years were significantly more likely to be screened for chlamydia than sexually active women aged 15 to 16 years in all years (e.g., 47% vs. 36% in 2005, P <0.001). After stratification by age, black women remained more likely to be screened for chlamydia than white women (Table 2, Fig. 2).

Percentage of Medicaid-Insured Women aged 15 to 21 Years Who Were Sexually Active and Percentage of Sexually Active Medicaid-Insured Women Aged 15 to 21 Years Screened for Chlamydia by Race and Ethnicity, Age Group, and Year (2002–2005)
Figure 1.
Figure 1.:
Percentage of sexually active Medicaid-insured women aged 15 to 21 years screened for chlamydia by race and ethnicity (2002–2005).
Comparison of the Percentage of Black Versus White Sexually Active Medicaid-Insured Women, Aged 15 to 21 Years, Screened for Chlamydia by Age Group, and Year (2002–2005)
Figure 2.
Figure 2.:
Percentage of sexually active Medicaid-insured women aged 15 to 21 years screened for chlamydia by race and age group (2002–2005).

Among women identified as having been screened for chlamydia, approximately 50% of them were identified only by codes for laboratory services (no medical care provider information was available), 41% were identified by codes for acute care hospital services, and 2% were identified by codes for visits to obstetrician-gynecologists.


Despite its ranking as one of the top 10 priority preventive services by the National Commission on Prevention Priorities,12 chlamydia screening remains underutilized. Annual chlamydia screening is essential in protecting the reproductive health of young women. We found that overall chlamydia screening rates increased each year for sexually active, Medicaid-insured women aged 15 to 21 years from 2002 to 2005, and that screening rates were highest among black women and women aged 19 to 21 years. Despite the annual increase in screening, the rates were still suboptimal for all demographic groups.

Greater screening rates among black women are encouraging because minority populations are disproportionally burdened by chlamydia13 and also because many studies have shown that providers caring for predominantly minority patient populations do not generally perform as well as those who care for nonminority populations in many health measures.14 Future research should identify whether the difference in chlamydia screening between black women and white women is due to different chlamydia prevalences within each subpopulation or provider and practice characteristics. These future studies will help us in developing more effective interventions to improve chlamydia screening rates among all women, and thus to identify more chlamydial infections.

Several strategies for increasing chlamydia screening of young sexually active women by changing provider behavior have been rigorously evaluated.15 Not only were these interventions complicated, costly, and time consuming, but they were not found to be effective, nor would they be feasible for widespread implementation. Simple and effective structural interventions hold the most promise for increasing chlamydia screening among young sexually active women. For example, placing a chlamydia swab next to Pap test collection materials was found to be effective in increasing chlamydia screening.16 Other effective interventions may include computerized reminders17 and bundling chlamydia screening with other laboratory testing such as liquid-based Pap testing and urinalysis.8

We demonstrate that MarketScan Medicaid claims data can be used as a tool for monitoring chlamydia screening trends over time by race and ethnicity. Although this method has limitations, it can be used to triangulate the status of chlamydia screening in the US along with other methods of estimating chlamydia screening, such as national health care survey data, and HEDIS measures.7–9 Using Medicaid child claims data from the MarketScan database in addition to these other measures offers the advantage of tracking time trends in chlamydia screening by race and ethnicity.

We found that most chlamydia tests were reported from the laboratory rather than by physicians or clinics, indicating that most providers who ordered a chlamydia test did not submit a claim for it. This administrative database will not be useful to identify the clinical venues where testing is occurring that could be targeted for interventions designed to increase chlamydia screening.

Our study has some limitations. First, we had claims data only for women aged 21 years and younger. Chlamydia screening rates among Medicaid-insured women aged 22 to 25 years should be assessed, as these women are also at high risk of chlamydial infection. Second, our findings cannot be generalized to the entire population of Medicaid-insured women in the United States, as our data were not nationally representative. However, our overall screening rates are comparable with the HEDIS estimates for women aged 16 to 20 years for the same time period. Third, we may have either overestimated or underestimated chlamydia screening coverage. Our estimates may be artificially high because we included only women with ICD-9 or CPT codes for reproductive health services, thus not capturing all sexually active women. However, the proportion of women aged 15 to 21 years identified as sexually active in our study was comparable with that identified by the 2002 National Survey of Family Growth.18 Additionally, it is likely that our screening estimates are overestimates of true screening because we could not distinguish screening tests for asymptomatic women from diagnostic tests for symptomatic women. Conversely, our estimates may be artificially low by assuming that all women with codes for reproductive health services were sexually active or by not capturing chlamydia testing at an encounter where a medical care claim or a laboratory claim was not made. Finally, we were unable to estimate the effect of chlamydia screening by region or state, which could be helpful in developing targeted interventions to increase chlamydia screening of young women with Medicaid insurance.

Young, Medicaid-insured women are at higher risk for chlamydia compared with young women with other insurance types.5 Although chlamydia screening rates in this population have increased over time, they remain suboptimal and, thus, interventions and policies should be developed to increase them. Further, all young sexually active women, regardless of insurance type and race and ethnicity, are at risk for chlamydia and should be screened to protect them from the devastating potential consequences of an untreated chlamydial infection. To protect the reproductive health of young women, we need to improve chlamydia screening rates through effective structural interventions. These interventions should make chlamydia screening a normative practice for all sexually active young women to avoid further stigmatization, especially women of high-risk subpopulations. Along with national health care survey data and HEDIS measures, the method described in this article can be used to evaluate the effectiveness of these interventions.


1. Centers for Disease Control and Prevention. Sexually Transmitted Disease Surveillance, 2007. Atlanta, GA: US Department of Health and Human Services, 2008.
2. American College of Obstetricians and Gynecologists Committee on Adolescent Health Care. ACOG Committee Opinion No. 301: Sexually transmitted diseases in adolescents. Obstet Gynecol 2004; 104:891–898.
3. Centers for Disease Control and Prevention. Sexually transmitted diseases treatment guidelines [Erratum in: MMWR Recomm Rep 2006; 55:997]. MMWR Recomm Rep 2006; 55:1–94.
4. US Preventive Services Task Force. Screening for chlamydial infection: US Preventive Services Task Force recommendation statement. Ann Intern Med 2007; 147:128–134.
5. Tao G, Tian LH, Peterman TA. Estimating Chlamydia screening rates by using reported sexually transmitted disease tests for sexually active women aged 16 to 25 years in the United States. Sex Transm Dis 2007; 34:180–182.
6. Centers for Medicare and Medicaid Services. Medicaid. Available at: Accessed March 18, 2009.
7. National Committee for Quality Assurance. The State of Health Care Quality 2006, Chlamydia screening. Available at: Accessed March 18, 2009.
8. Hoover K, Tao G. Missed opportunities for Chlamydia screening of young women in the United States. Obstet Gynecol 2008; 111:1097–1102.
9. Hoover K, Tao G, Kent C. Low rates of both asymptomatic Chlamydia screening and diagnostic testing of women in US outpatient clinics. Obstet Gynecol 2008; 112:891–898.
10. Nguyen TQ, Ford CA, Kaufman JS, et al. Infrequent chlamydial testing among young adults: Financial and regional differences. Sex Transm Dis 2008; 35:725–730.
11. Thompson Healthcare Inc. MarketScan Databases User Guide and Database Dictionary, Multi-state Medicaid Database, 2006 Edition. Englewood, CO: Thompson Healthcare Inc, 2007.
12. Maciosek MV, Coffield AB, Edwards NM, et al. Priorities among effective clinical preventive services: Results of a systematic review and analysis. Am J Prev Med 2006; 31:52–61.
13. Miller WC, Ford CA, Morris M, et al. Prevalence of chlamydial and gonococcal infections among young adults in the United States. JAMA 2004; 291:2229–2236.
14. Blustein J. Who is accountable for racial equity in health care? JAMA 2008; 299:814–816.
15. Scholes D, Grothaus L, McClure J, et al. A randomized trial of strategies to increase Chlamydia screening in young women. Prev Med 2006; 43:343–350.
16. Burstein GR, Snyder MH, Conley D, et al. Chlamydia screening in a Health Plan before and after a national performance measure introduction. Obstet Gynecol 2005; 106:327–334.
17. Goetz MB, Hoang T, Bowman C, et al. A system-wide intervention to improve HIV testing in the Veterans Health Administration. J Gen Intern Med 2008; 23:1200–1207.
18. Mosher WD, Chandra A, Jones J. Sexual behavior and selected health measures: Men and women 15–44 years of age, United States, 2002. Adv Data 2005;1–55.
© Copyright 2009 American Sexually Transmitted Diseases Association