VARIATIONS IN CATARACT-EXTRACTION RATES IN MEDICARE PREPAID AND FEE-FOR-SERVICE SETTINGS

Objective.-To compare rates of cataract extraction in 2 prepaid health settings and in traditional fee-for-service (FFS) settings. Design.-A cross-sectional analysis using 1993 health maintenance organization ( HMO) Medicare claims and encounter files, the Health Care Financing Ad ministration (HCFA) 5% Medicare Part B provider/supplier file, and the HCFA October 1992 100% Medicare population file. Setting.-Southern Ca lifornia Medicare FFS settings and the staff-model and independent pra ctice association (IPA) plans of a large California HMO. Patients.-199 3 Medicare beneficiaries aged 65 years and older, The study included 4 3 387 staff-model HMO enrollees, 19 050 IPA enrollees, and 47 150 FFS beneficiaries (a 5% sample of all Southern California FFS beneficiarie s). Main Outcome Measure.-Age and risk-factor adjusted rates of catara ct extraction per 1000 beneficiary-years. Results.-After controlling f or age, sex, and diabetes mellitus status, FFS beneficiaries were twic e as likely to undergo cataract extraction as were prepaid beneficiari es (P<.01). Female FFS beneficiaries were nearly twice as likely to un dergo the procedure as were male FFS beneficiaries (P<.001); there wer e no extraction rate differences by sex in the prepaid settings. Concl usion.-Because of the potential implications for vision care in the el derly, the significantly different rates of cataract extraction in FFS and prepaid settings warrant further clinical investigation to determ ine whether there is overuse in FFS vs underuse in prepaid settings. S uch investigations must assess the appropriateness of cataract surgery by evaluating its use relative to clinical need.