The decline in the Blue Cross Plan admission rate: four explanations.

Between 1968 and 1979, there occurred a steady decrease in the hospital admission rate for Blue Cross Plan members, in contrast to the steady increase in the admission rate for the under-65 U.S. population as a whole. Four general factors were studied to explore the reasons for this relative decrease: utilization control and cost containment activities instituted by Blue Cross Plans, the decline in Plan nongroup membership, duplicate coverage within families, and deficiencies in the family factor technique to estimate overall Plan membership. With some interesting exceptions within one of the factors, all four offer plausible explanations for the decline in the admission rate among Blue Cross Plan members.