• Pihla Tommiska, Teemu Luostarinen, Jaakko Kaprio, Miikka Korja, Kimmo Lönnrot, Riku Kivisaari, and Rahul Raj.
• 1Department of Neurosurgery, University of Helsinki and Helsinki University Hospital.
• J. Neurosurg. 2022 Apr 1; 136 (4): 118611931186-1193.

ObjectiveThe number of surgeries performed for chronic subdural hematoma (CSDH) has increased. However, these changes have been poorly reported. The authors aimed to assess the national incidence of surgeries for CSDH in Finland during an 18-year time period from 1997 to 2014. They hypothesized that the incidence of CSDH surgeries has continued to increase, particularly among the elderly.MethodsA nationwide register-based follow-up study was performed using the Finnish Care Register for Health Care. All adult patients undergoing primary CSDH surgeries during 1997-2014 were included. The study population was followed up from the time of CSDH surgery until death or the end of follow-up on December 31, 2017. The incidences of CSDH surgery per 100,000 person-years were calculated separately in each age group and sex. Age standardization was performed for those 20 years of age and older with weights from the 2013 European Standard Population. Negative binomial regression models were used to assess changes in incidence rate ratios (IRRs) during the study period.ResultsIn total, 9280 patients were identified. The age-standardized incidence of CSDH surgery increased from 12.2 to 16.5 per 100,000 person-years during 1997-2014. The age- and sex-adjusted incidence of CSDH surgery increased by 30% (IRR 1.30, 95% CI 1.20-1.41). The age- and sex-adjusted incidence increased more in the older age groups, with an IRR of 1.24 for those aged 60-69 years, 1.32 for those 70-79 years, 1.46 for those 80-89 years, and 1.85 for those aged 90 years or older. The adjusted incidence did not increase for those aged 18-59 years. The sex difference (2:1 men/women) was consistent throughout the study period, with a higher incidence among men. One year after the primary surgery, 19% of the population had a resurgery, and the 1-year case fatality rate was 15%. The median age of patients increased from 73 to 76 years.ConclusionsDuring the past 2 decades, the age- and sex-adjusted incidence of CSDH surgery has increased in Finland, with major increases for those aged 60 years or older. This increase is likely to continue in parallel with the aging population and increased life expectancies.

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