Episodes of illness and access to care in the inner city: a comparison of HMO and non-HMO populations.

Using data from a 1974 household survey, accessibility to ambulatory care is compared for residents of an inner-city area (East Baltimore) whose usual source of care is an HMO (the East Baltimore Medical Plan) and residents of the same area with other usual sources of care. Accessibility is measured by the probability of receiving care for an episode of illness. Results from multivariate linear and probit regressions indicate that children using the HMO are more likely to receive care than are children with other usual care sources, but no significant differences in the probability of receiving care are found among adults. Evidence of a substitution of telephone care for in-person care is also found among persons using the HMO. Data from a 1971 household survey of the same area suggest that selectivity is not an important confounding factor in the analysis.