STROKE IN A DEFINED ELDERLY POPULATION, 1967-1985 - A LESS LETHAL ANDDISABLING BUT NO LESS COMMON DISEASE

Background and Purpose Decline in stroke mortality in recent decades h as been well documented in the United States and other countries. This study, based on a well-defined population with comprehensive medical records available for research purposes, seeks to explain decline in s troke mortality among older persons between 1967 and 1985. The study s pecifically explores the competing explanatory mechanisms of decreased incidence of stroke versus decreased case-fatality rate, Methods We c onducted a retrospective analysis of three successive period cohorts ( 1967 through 1971, 1974 through 1978, and 1981 through 1985) of person s greater than or equal to 65 years of age enrolled in a large group m odel HMO in a metropolitan community, All new hospitalized and a sampl e of nonhospitalized strokes were ascertained, and samples of first-ev er strokes were studied. Incidence, case-fatality rates, survival time s, and comorbidities were compared across cohorts. Results There was n o significant change in stroke incidence over time. however, I-month c ase fatality declined dramatically from 33% in 1967 through 1971 to 18 % in 1981 through 1985 (P<.01); median survival increased from 213 to 1092 days. In dices of reduced severity included declines in coma from 27% to 12% (P<.01) and in wheelchair- or bed-bound status from 40% to 30%, (P=.067). Casts with and without CT scan in 1981 to 1985, when t his procedure became widely available in the health plan, were similar in severity, thereby reducing the possibility of ascertainment bias. Conclusions In this well-defined older population, stroke has become a less lethal and disabling though no less common disease. This finding fails to support the ''compression of morbidity'' hypothesis while su pporting a model of delayed progression for stroke in this age group.