Design of the CHina Epidemiology Research in Subarachnoid Haemorrhage (CHERISH) study

Rationale Limited epidemiological data exist on subarachnoid haemorrhage (SAH) in China. Effective prevention requires knowledge of the rates and risk factors for SAH the most lethal type of stroke that most often affects younger adults. We report the methods and the initial experience of a new study to address this deficiency. Aims To determine the incidence, risk factors, management and outcomes of SAH. Design The CHina Epidemiology Research In Subarachnoid Haemorrhage (CHERISH) is a prospective, population-based, case–control study in a defined region (study population 1.7 million) of the city of Baotou in Inner Mongolia, China. Methods Cases of spontaneous SAH are identified using standard definitions through prospective surveillance of all major acute care hospitals with neurology/neurosurgery facilities, small hospitals/clinics, and the single city crematorium over a 2-year period. Verbal autopsy procedures are used to ascertain the probable causes of deaths outside of hospital. For each case, two nonrelative controls without SAH are matched by age (5-year strata), gender, and district of residence. Data are collected on socio-demography, lifestyle factors, and medical history, and blood is taken for the extraction and storage of DNA. Details of the clinical features, presentation, and management of SAH are obtained from cases, and survivors provide details on health care utilisation, physical function, health-related quality of life, and complications, at 6-months. Study outcomes The primary outcomes are overall, age- and gender-specific incidence, relative (odds ratios) and population-attributable risks for defined exposures, and 28-day and 6-month case fatality ratios and other outcomes. Conclusions Preliminary experience confirms the completeness of the surveillance methods, with no clear missed out-of-hospital cases of SAH with sudden death, and of high participation and reliable data collection procedures. CHERISH is well placed to provide reliable estimates of the burden of SAH in China.