The relation of household income to mammography utilization in a prepaid health care system.

Managed care organizations should be expected to provide equivalent access to preventive and screening services to all members. We studied mammography in 1,667 women members of one HMO who had an overall utilization rate of 84.9%. Significant correlates of mammography utilization included age, estimated household income, and division of the managed care organization in which the member was enrolled. Each $10,000 increment of income increased mammography rates by 2.5 percentage points (95% confidence interval [CI], 1.4% to 3.6%), independent of age and division. Our findings suggest that coverage for mammography services is not sufficient to ensure equivalent use of screening across income groups.