Diverging trends in hospitalization: fact or artifact?

It has been noticed recently that hospital use by Blue Cross enrollees has fallen substantially in the last decade and that this decline is in marked contrast to relatively stable utilization reported by hospitals. The trends in length of stay in the two data sources are almost identical--all the differential is attributable to differing trends in admission rates: a sharp increase for all persons under 65 years of age in contrast to a moderate decline for Blue Cross members. These two trends are diverging at the rate of 2 per cent per year. Household survey data for the under-65 population with private health insurance also indicates an increasing admission trend, in contrast to the Blue Cross figures, even though Blue Cross covers half the insured population. About half of the differential trend can be accounted for by the increasing rate of duplicate coverage, which artificially increases the enrollments reported by carriers. The increased duplicate coverage is a reflection of more multiple-earner families, a shifting occupation mix, better fringe benefits, higher unemployment and smaller families. Part of the increased admissions for the total under-65 population is due to Medicare coverage for the disabled and to Medicaid. Most important, it is apparent that existing data provide an inadequate and potentially misleading picture of the most crucial measures of utilization.