EXTENDING HEALTH MAINTENANCE ORGANIZATION INSURANCE TO THE UNINSURED - A CONTROLLED MEASURE OF HEALTH-CARE UTILIZATION

Objective.-To investigate the utilization of health care services of p reviously uninsured low-income patients after becoming insured by a he alth maintenance organization (HMO). Design.-Retrospective study of ut ilization in a previously uninsured study group compared with an age- and sex-matched randomly selected control group of commercial HMO enro llees. Setting.-Group model HMO. Patients.-A study group of 346 previo usly uninsured low-income patients and 382 controls. Measures.-Outpati ent visits for primary and specialty care, outpatient pharmacy, labora tory, and radiology use, and inpatient admissions and hospital days ov er a 2-year period. Self-reported health status measures were obtained to control for differences in health status. Principal Findings.-Ther e were no differences between the study and control groups in hospital admissions, hospital days, and measures of outpatient laboratory, pha rmacy, and radiology use. The odds of having an outpatient visit per p atient per month was 30% higher for the study group. Approximately hal f the increase in the odds ratio for outpatient visits was related to the worse self-perceived health status of the study group. While both groups utilized more services in the early phase of their enrollment, the intensity of this start-up effect was similar for both groups. Con clusions.-Compared with a commercial group of the same age and sex, th e patterns of utilization were similar and the financial costs of care were only moderately more for a previously uninsured group provided w ith comprehensive HMO insurance. With the growth of managed care, thes e data should be beneficial in the development of health care programs for the growing number of uninsured Americans.