A multivariate analysis of the likelihood and volume of preventive visit demand in a prepaid group practice.

An economic framework for the investigation of the demand for preventive medical care services is suggested and empirical models for the likelihood and volume of preventive physician visits are specified. These are tested using data on 3,892 individuals enrolled in the Kaiser Foundation Prepaid Health Plan of Portland, Oregon. Preventive visits, delineated by the Kaiser Clinical Behavioral Classification System, included general medical examinations, eye examinations, well-child care and immunization services. Multiple regression is used to estimate the likelihood of preventive visits for all persons and the volume of preventive visits for users. Income and coinsurance were the most significant economic variables in the likelihood equation, possessing the expected positive and negative signs, respectively. The usual findings of a positive education effect and negative family size effect were supported by the results. The economic variables were less significant in the volume equations than in the likelihood equations, suggesting that system and physician effects may neutralize these factors. Females were more likely to make a preventive visit than were males and the relatively young and old were the heaviest age-group users of preventive care. Perceived helath status did not appear to significantly affect preventive care demand.