Incidence of subarachnoid hemorrhage is decreasing together with decreasing smoking rates

Objective:To determine the nationwide incidence of subarachnoid hemorrhage (SAH) and report nationwide changes in smoking rates between 1998 and 2012 in Finland.Methods:In this register-based study, we utilized the nationwide Causes of Death Register and Hospital Discharge Register in identifying SAH events between 1998 and 2012. Population statistics in Finland, which were obtained through a database of Statistics Finland, were used to calculate crude annual incidence rates of SAH. For the direct age standardization of crude incidence rates, we used the European Standard Population (ESP) 2013. Data on changes in nationwide smoking rates between 1998 and 2012 were extracted from a database of the National Institute for Health and Welfare.Results:For the total of 79,083,579 cumulative person-years, we identified 6,885 people with SAH. Sudden deaths from SAH away from hospitals or in emergency rooms accounted for 1,771 (26%) of the events. Crude nationwide annual incidence rates varied between 6.2 and 10.0 per 100,000 persons, and increased by age particularly in women. Among 70- to 75-year-old women, the incidence of SAH was highest (22.5 per 100,000 persons). The 3-year average of ESP standardized incidence decreased 24% from 11.7 in 1998-2000 to 8.9 per 100,000 persons in 2010-2012. Daily smoking decreased 30% between 1998 and 2012.Conclusions:The incidence of SAH seems to be decreasing. This tendency may be coupled with changes in smoking rates. The incidence of SAH in Finland is similar to other Nordic countries.