Trends in the incidence of subarachnoid hemorrhage in South Korea from 2006-2009: An ecological study

Objective: The purpose of this study is to investigate trends in the incidence of subarachnoid hemorrhage (SAH) in South Korea from 2006-2009. Methods: We used the national health claim database managed by Health Insurance Review and Assessment Service, which contains all hospital records of every Korean citizen. Patients with SAH were defined as International Classification of Diseases-10 codes with a hospitalization period of ≥14 days or death within 14 days of hospitalization. We evaluated trends in the incidence of SAH during a 4-year period using the Cochran-Armitage trend test. Results: We identified 35,263 patients with SAH among adult patients (≥18 years old) from 2005-2009. Age-adjusted SAH incidence rates decreased from 13.4 in 2006 to 12.4 in 2009/100,000 men (P = 0.0025) and women also showed a decrease from 19.4-17.3/100,000 (P < 0.0001). However, this decreasing pattern was not shown in patients less than 50 years of age. SAH incidence showed gender differences dependent on age; men who were 40 years old or less had a higher incidence than women. Conclusions: The age-adjusted incidence rates of SAH were slightly decreased in South Korea. Further research should be conducted to identify the clinical risk factors to reduce SAH incidence rates even more, especially in younger people.