Decreased severity of brain infarct can in part explain the decreasing case fatality rate of stroke

Case fatality rates for stroke has declined in most Western industrialized countries during recent decades. One possible explanation for this is a decrease in the severity of stroke symptoms. We therefore sought evidence for a change in stroke severity and its relationship with case fatality rates.

We compared the severity of symptoms among first-ever stroke patients in 2 population-based prospective stroke registers maintained during 1972 to 1973 and 1989 to 1991 in Finland. Patients who were evaluated by study assistants or the investigator during the first week after the onset of symptoms were included in the study, and their severity of symptoms was assessed with the use of comparable scales modified from the Scandinavian Stroke Scale.

A total of 244 and 594 patients were registered, and a portion of them (155 [63.5%] and 360 [60.6%]) were included in the analyses in the registers for Espoo-Kauniainen from 1972 to 1973 and for 4 separate districts in Finland from 1989 to 1991, respectively. The death rates during the first week among those who were not included did not differ between the registers. The severity of symptoms decreased significantly between the registers in both patients with brain infarct or intracerebral hemorrhage but not in those with subarachnoid hemorrhage. The severity of symptoms was an independent factor of case fatality at 1 month.

The severity of symptoms of brain infarcts has decreased and can in part explain the decreased case fatality rate of stroke in Finland. However, the change in patients with intracerebral hemorrhage may be overestimated due to undiagnosed intracerebral hemorrhages in the first register resulting from the lack of brain CT.