Utilization of services of an HMO by new enrollees.

This study investigates whether there is a built-up demand for health services that surfaces when people enroll through a group plan in a Health Maintenance Organization. The study population consists of newly enrolled subscriber units of the Kaiser Foundation Health Plan (Oregon Region). The utilization variables examined include the number of inpatient and outpatient contacts with the Plan, the number and type of specific services performed, and the type of outpatient contact. The enrollees were followed over 12 quarters (three years). The analysis showed that the first quarter stood out in three respects: its average number of inpatient and outpatient contacts were the lowest of any quarter; the mean numbers of radiology services and laboratory tests per outpatient contact were the highest during this quarter; and the highest proportion of regularly scheduled contacts and the lowest rate of patient cancellation of visits occurred during the first quarter. Hence, these data are not supportive of the idea of a built-up demand. Rather they suggest that the enrollee requires some time to learn how to deal with the system; and, once a new member contacts the system, the system may perform a number of tests to obtain baseline data about the enrolee. Additional analysis did not suggest the presence of any time trends in the utilization data.