INSURANCE TYPE AND CHOICE OF HOSPITAL FOR CORONARY-ARTERY BYPASS GRAFT-SURGERY

Objective. To examine the effect of insurance type on the relationship between hospital attributes and patient flows, with particular attent ion to whether HMO enrollees are more or less likely than other patien ts to receive care at high-quality hospitals and whether HMO enrollees travel farther to receive care.Data Sources/Study Setting. Data on pa tient flows, taken from discharge abstracts compiled by the California Office of Statewide Health Planning and Development. Our sample consi sts of patients undergoing coronary artery bypass graft surgery (CABG) in 1991 who resided in three California markets. Only patients under the age of 65 and insured by HMOs, Blue Cross/Blue Shield, or other co mmercial insurance were included. Hospital quality is based on hospita l-specific measures of excess mortality from CABG. Other hospital attr ibutes were taken from American Hospital Association survey data. Stud y Design. Conditional-choice models were used to estimate the probabil ity that patients would receive care at any given hospital as a functi on of their insurance type and the hospital's attributes. Principal Fi ndings. Patients were more likely to receive care from hospitals close r to their residence. However, HMO patient flows were less sensitive t o proximity. In general, the likelihood that an HMO enrollee received care at a given hospital was positively related to hospital quality. M oreover, quality had a greater effect on patient flows for HMO enrolle es than for non-HMO enrollees. However, the evidence suggests that the effect of quality on patient flows is neither uniform across markets nor across HMOs. Conclusions. HMOs do not appear to direct patients to low-quality hospitals. However, heterogeneity among HMOs and across m arkets suggests that buyers must recognize that choosing an HMO involv es greater scrutiny than simply picking a plan labeled ''HMO.''