Do HMO market level factors lead to racial/ethnic disparities in colorectal cancer screening? A comparison between high-risk Asian and Pacific Islander Americans and high-risk whites

Background: Few studies have explored health care market structure and colorectal cancer (CRC) screening test use, and little is known whether market factors contribute to racial/ethnic screening disparities. Objective: We investigated whether HMO market level factors, controlling for individual covariates, differentially impact Asian American and Pacific Islander (AAPI) subjects' access to CRC screening compared with white subjects. Research Design and Methods: We used random intercept hierarchical models to predict CRC test use. Individual-level survey data was linked to market data by metropolitan statistical areas from InterStudy. Subjects: Insured first-degree relatives, ages 40-80, of a random sample of colorectal cancer cases identified from the California Cancer Registry: 515 white subjects and 396 AAPI subjects residing in 36 metropolitan statistical areas (MSAs). Measures: Dependent variables were receipt of (1) annual fecal occult blood test only; (2) sigmoidoscopy in the past 5 years; (3) colonoscopy in the past 10 years; and (4) any of these tests over the recommended time interval. Market characteristics were HMO penetration, HMO competition, and proportion of staff/group/network HMOs. Findings: Market characteristics were as important as individual-level characteristics for AAPI but not for white subjects. Among AAPI subjects, a 10% increase in the percent of group/staff/network model HMO was associated with a reduction in colonoscopy use (28.9% to 20.5%) and in receipt of any of the CRC tests (53.2% to 45.4%). Conclusions: The prevailing organizational structure of a health care market confers a penalty on access to CRC test use among high-risk AAPI subjects but not among high-risk white subjects. Identifying the differential effect of market structure on race/ethnicity can potentially reduce the cancer burden among disadvantaged racial groups.