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Chlamydia Screening of At-Risk Young Women in Managed Health Care: Characteristics of Top-Performing Primary Care Offices

Ray, Midge N. MSN, RN*†; Wall, Terry MD, MPH†§; Casebeer, Linda PhD†‡¶; Weissman, Norman PhD*†**; Spettell, Claire PhD; Abdolrasulnia, Maziar MPH, MBA*‡; Mian, M Anwarul Huq MBBS, MPH*; Collins, Blanche MHSE; Kiefe, Catarina I. PhD, MD†**‡‡; Allison, Jeroan J. MD, MS†¶**

Author Information
Sexually Transmitted Diseases: June 2005 - Volume 32 - Issue 6 - p 382-386
doi: 10.1097/01.olq.0000162367.39209.01
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CHLAMYDIA TRACHOMATIS IS THE MOST common sexually transmitted bacterial infection in the United States, with 834,555 cases reported in 20021 and population-based projections of three million new cases each year.2 Most women infected with C. trachomatis are asymptomatic, but many of those infected ultimately experience adverse health outcomes such as pelvic inflammatory disease (PID), infertility, and ectopic pregnancy.3 There are simple, evidence-based, effective approaches to testing and treating chlamydial infection, and screening is cost-effective in reducing adverse health consequences.4–7

Although professional and regulatory organizations are promoting screening for at-risk women,8,9 national screening rates of top-performing managed care plans in 2003 were only 38.5% for sexually active 16- to 26-year-old women.10 In one exceptional study designed to increase chlamydia screening for adolescent women seen in a managed care clinic, Shafer reported a postintervention screening rate of 65%.11 Even given the increased emphasis on screening, the national prevalence of chlamydial infection among sexually active adolescents remains between 3% and 28%, depending on the population studied.1 Because overall low screening rates demand further attention, we examined a population of primary care offices participating in a large managed care plan to identify characteristics associated with high screening rates.

Materials and Methods

We received approval from the Institutional Review Board at the University of Alabama at Birmingham and subsequently conducted a cross-sectional analysis of baseline data generated from the randomized trial, “An Internet Intervention to Promote Chlamydia Screening.” This study, which was funded by the Agency for Healthcare Research and Quality as part of the second Translating Research Into Practice (TRIP II) initiative,12 tested a provider-based Internet intervention that featured a quality improvement toolbox with feedback on screening patterns. The goal of the intervention was to increase chlamydia screening for asymptomatic, at-risk young women by physicians participating in a managed care plan (health maintenance organization/point of service).

In 2000, the National Committee for Quality Assurance (NCQA) introduced the Health Plan Employer Data and Information (HEDIS) measure for chlamydia screening.8 The HEDIS chlamydia measure uses administrative data to identify at-risk young women through evidence of sexual activity. The measure requires that all at-risk women be screened at least once during the preceding year. For this study, chlamydia screening rates were calculated according to the HEDIS 2001 technical specifications.13 Eligible female patients were between the ages of 16 and 26 and enrolled continuously in the managed care plan for calendar year 2000. Eligible young women were identified as at risk and included in the denominator if administrative, pharmacy, or laboratory data revealed: 1) a diagnosis of a sexually transmitted disease or pregnancy, 2) a prescription for oral contraceptives (OCP) or a contraceptive device, (3) pregnancy testing, or (4) screening for cervical cancer. Individuals could fulfill more than one denominator eligibility criterion. The measure excluded women receiving OCP in conjunction with isotretinoin (Acutane) and those having a pregnancy test followed by either a prescription for isotretinoin or an x-ray; this exclusion was applied only to those women who did not meet other denominator inclusion criteria. The numerator for the HEDIS screening rate consisted of all young women with a current procedural terminology (CPT) code for chlamydia screening during calendar year 2000.

Aetna Integrated Informatics, Inc., the performance measurement subsidiary of Aetna, Inc., identified primary care physician offices caring for women aged 16 to 26 who were enrolled in an Aetna health maintenance organization or point of service plan. Selected markets (California, Texas, Colorado, Louisiana, St. Louis, and Illinois) were excluded because these providers manage their claims data through private vendors. Aetna calculated chlamydia screening rates at the office level, and therefore, for this study, all physicians in a given office were assigned the same screening rate. Because primary care physicians are responsible for coordinating care for their patients, a chlamydia screen performed by any physician in the office was credited to the primary care physician if the test was reported.

Lacking patient-level information, we used office location as a proxy for patient socioeconomic position. Median household income for the office zip code was taken from the U.S. Census data, 1999. For 1.4% of the zip codes in our data, there was no income data available, which resulted in missing data when analyzing for median household income. Based on the income distribution in the Census, we defined lower-income zip codes as those with a median household income of less than $30,000.

Physician characteristics were derived from the managed care administrative data and the American Medical Association (AMA) physician survey. Physicians were first electronically matched by name; duplicates and nonmatches were resolved by manual review of additional office-level data such as address. We were able to match 98.4% of the physicians in our data with data from the AMA masterfile. There was no ethnicity reported on 15.8% of the physicians.

Only primary care physicians with a specialty of pediatrics, internal medicine, family practice, or general practice were included. Internists and pediatricians with subspecialty board certification were not counted as primary care physicians. Obstetrician/gynecologists were excluded because some were participating in primary care and others were not, creating difficulty in attributing responsibility for primary care. If an obstetrician/gynecologist performed the screen in an office that had a participating physician, the screening would be counted at the office level.

For all analyses, study variables were 1) measured at the office level (number of physicians/office, median income for office zip code), 2) measured at the patient level but available only at the office level (HEDIS screening rates), or 3) measured at the physician level and aggregated at the office level (physician age, sex, ethnicity, type of degree, country of graduation from medical school). Physician characteristics (except age) were first taken as proportions at office level and then averaged by office type. Therefore, all analyses were conducted at the office level. The main outcome was a dichotomous variable indicating if the office was ranked within the top decile for chlamydia screening based on data from this project. We chose the top decile because it parallels the method that NCQA uses in determining top performance for all reporting managed care plans. We compared characteristics of top-performing offices with characteristics of other offices using statistical tests appropriate to the distribution of the independent variable. We also compared office characteristics by location in a lower-income or other zip code area. A multiple logistic regression model, with the office as the unit of analysis, determined independent associations with top-performance status.


The study sample consisted of 975 offices representing 3523 primary care providers from 26 states. The mean (standard deviation) chlamydia screening rate for all offices was 16.2% (11.8), and the median (interquartile range) chlamydia screening rate was 13.95% (7.69–21.74). The average physician age was 44.4 years, and most physicians were male (66.2%) and white (80.4%). Most physicians were either in family practice (51.3%) or internal medicine (35.0%).

Overall, 7.2% of the offices were located in a zip code with a median income of less than $30,000. Compared with other offices, offices located in lower-income zip code areas have higher chlamydia screening rates (25.7%, 15.3%, P = 0.000) and were more likely to be within the top decile of screening performance (30.4%, 8.1%, P = 0.000). In addition, offices located in lower-income areas had more black physicians (12.2%, 5.3%, P = 0.007), more Hispanic physicians (8.2%, 4.0%, P = 0.054), and fewer doctors of osteopathy (14.4%, 25.1%, P = 0.023) (Table 1).

Characteristics of Primary Care Offices (n = 961) Overall and by Location in Lower-Income Zip Code Area versus Other Area

Compared with other offices, top-performing offices had, on average, more physicians per office (6.91, 4.54, P = 0.000), more female physicians (40.0%, 33.1%, P = 0.050), more black physicians (12.5%, 5.1%, P = 0.001), and fewer doctors of osteopathy (16.2%, 25.4%, P = 0.021) (Table 2). Top-performing offices were more likely to be located in a zip code with a median income of less than $30,000 (22.6%, 5.5%, P = 0.001). Chlamydia screening rates of practices whose physicians were all female (n = 113) compared with the practices whose physicians were all male were not significantly different. After adjustment for multiple confounders in the logistic regression, only location in lower-income zip code and percentage of black physicians in the office were significantly associated with top performance for chlamydia screening (Table 3).

Characteristics of Primary Care Offices (n = 975) With Top Performance on the Health Employers Data and Information Set (HEDIS) Screening Measure versus Other Primary Care Offices
Odds Ratios and 95% Confidence Intervals from Logistic Regression for Top Performance on Chlamydia Screening Among 810 Primary Care Offices


Our cross-sectional analysis of administrative data from a large managed care organization revealed low rates of chlamydia screening for at-risk young women in 2000. In addition, we found that offices with higher proportions of black physicians and offices located in lower-income zip codes were more likely to be top performers on the screening measure.

Although low, screening rates from this study are comparable to those from other managed care organizations. The mean HEDIS chlamydia screening rate for all reporting managed care organizations across the nation in 2002 was 26.7% for women between 16 and 20 years old and 24.5% for women between 21 and 26 years old. Top-performing managed care plans reported screening rates of 38.5% in the at-risk 16- to 26-year-old group.10 Similar screening rates have also been found by other investigators, with generally higher rates from provider self-report14,15 and lower rates from administrative data.16,17 Based on an algorithm driven by managed care administrative data, Mangione-Smith concluded that 43% to 54% of enrolled females (15–25 years old) were sexually active. Screening rates varied from 2% to 42% depending primarily on the type of clinic visit (eg, routine visit, acute illness, pregnancy screening, contraceptive counseling).17

Although we found that the proportion of female physicians in an office was not a predictor of screening after multivariable adjustment, other studies have reached contrasting conclusions.14 For example, Torkko reported that female providers were more likely to take a sexual history and test for C. trachomatis.15 Female physicians are more likely to perform preventive services, especially mammography, breast examinations, and screening for cervical cancer.18–21 Additional evidence suggests that female physicians may be more comfortable taking a sexual history and performing cervical cancer screening.15,18

To our knowledge, this is the first report showing that primary care offices with more black physicians have better chlamydia screening rates. Offices including black physicians are more likely to practice in lower-income areas,22 in which the risk of sexually transmitted disease is greater.23 These physicians may be better able to establish rapport with black patients, as suggested by several studies revealing increased patient satisfaction in race-concordant patient–physician relationships.24,25 Better rapport may lead to increased comfort in taking a sexual history, which is often an important trigger for screening. Black physicians may be more attuned to national statistics documenting an increased risk of sexually transmitted disease infection in patients with lower socioeconomic position.23

After adjustment for the ethnic mixture of physicians within offices, location in a lower-income zip code remained an independent predictor of performance. Although the characteristics of the office location may not directly reflect the patient socioeconomic position of an individual patient, it is reasonable to assume that practices located in lower-income zip codes may tend to serve patients with lower socioeconomic position.26 Furthermore, zip code areas are associated with substantial variation in chlamydia prevalence, although analyses based on the census tract are more reliable.27,28 Practicing in a lower-income zip code area may increase the provider’s suspicion of chlamydial infection, or these clinics may have instituted polices that promote screening. Cook found that self-reported screening was highest for practices located in metropolitan areas and with patient populations of more than 20% black.14

Our study suggests additional implications that may guide future improvement efforts. The top-performing practices should be more closely studied to understand how they overcome barriers to screening. Changes in practice, including routine sexual risk assessment, improved communication and education, changes in reimbursement for testing, and incentives for screening, may lead to improved screening practices. Perhaps physicians practicing in lower-income areas will have important lessons to teach about improving screening rates.

This study has important limitations. First, associations found by cross-sectional data analysis are not necessarily causal. Second, interpreting results from this study is subject to the “ecologic fallacy.” Lacking screening rates for individual physicians, all analyses were performed at the office level. Therefore, one should not attribute office-level findings to the individual physician. Third, although the HEDIS measure does exclude young women who are on oral contraceptives in conjunction with isotretinoin, it does not exclude when OCPs are prescribed for other medical benefits. Fourth, we only followed the screening rates for the primary care provider’s patients that participated in the managed care organization, which is a fraction of their total population. Fifth, the data were taken from the year in which NCQA first introduced the HEDIS chlamydia screening measure.8 As managed care organizations have responded to the new standard, chlamydia screening rates have increased slightly over the past 2 years.10 Consequently, patterns from initial observation may not hold currently. Sixth, being newly introduced, the HEDIS chlamydia measure has not undergone validation beyond the initial work of the NCQA at the time of this study. A recent study found that the HEDIS numerator, which relies on CPT codes from administrative data, significantly undercounts the number of screening tests actually performed.29 Furthermore, the HEDIS denominator fails to identify all young women at risk for infection. The HEDIS measure determines the risk status by seeking evidence from administrative data that the patient was sexually active. Tao recently found that for privately insured women aged 15 to 25 years rates of sexual activity were 60% by self-report but only 27% by HEDIS criteria.30 Seventh, although the managed care population we studied is geographically and demographically diverse, the results of this study may not be generalizable to the uninsured, fee-for-service population or populations in other states.


This study, along with several others, documents that screening for asymptomatic chlamydial infection in at-risk young women remains less than optimal. We examined office characteristics associated with top performance on the HEDIS chlamydia screening measure in a large managed care population. After adjustment for several confounding variables, only two factors were independently associated with high performance on the chlamydia screening measure: location in a lower-income zip code area and having more black physicians in the office.


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