Health maintenance organizations and hospital quality for coronary artery bypass surgery.

This study uses hospital discharge data for 1992-1994 to assess differences between HMO and insured non-HMO patients in California and Florida with regard to the quality of the hospitals used for coronary artery bypass graft (CABG) surgery. The authors found that commercially insured HMO patients in California used higher quality hospitals than commercially insured non-HMO patients, controlling for patient distance to the hospital. In contrast, commercially insured HMO and non-HMO patients in Florida were similarly distributed across hospitals of different quality levels, whereas Medicare HMO patients in Florida used lower quality hospitals than patients in the standard Medicare program. The authors conclude that the association between HMO coverage and hospital quality may differ across geographic areas and patient populations, possibly related to the maturity and structure of managed care markets.