Risk of cardiovascular events and death in the life after aneurysmal subarachnoid haemorrhage: a nationwide study

Background and aim The increased mortality rates of survivors of aneurysmal subarachnoid haemorrhage have been attributed to an increased risk of cardiovascular events in a registry study in Sweden. Swedish registries have however not been validated for subarachnoid haemorrhage and Scandinavian incidences of cardiovascular disease differ from that in Western European countries. We assessed risks of vascular disease and death in subarachnoid haemorrhage survivors in the Netherlands. Methods From the Dutch hospital discharge register, we identified all patients with subarachnoid haemorrhage admission between 1997 and 2008. We determined the accuracy of coding of the diagnosis subarachnoid haemorrhage for patients admitted to our centre. Conditional on survival of three-months after the subarachnoid haemorrhage, we calculated standardized incidence and mortality ratios for fatal or nonfatal vascular diseases, vascular death, and all-cause death. Cumulative risks were estimated with survival analysis. Results The diagnosis of nontraumatic subarachnoid haemorrhage was correct in 95.4% of 1472 patients. Of 11 263 admitted subarachnoid haemorrhage patients, 6999 survived more than three-months. During follow-up (mean 5.1 years), 874 (12.5%) died. The risks of death were 3.3% within one-year, 11.3% within five-years, and 21.5% within 10 years. The standardized mortality ratio was 3.4 (95% confidence interval: 3.1 to 3.7) for vascular death and 2.2 (95% confidence interval: 2.1 to 2.3) for all-cause death. The standardized incidence ratio for fatal or nonfatal vascular diseases was 2.7 (95% confidence interval: 2.6 to 2.8). Conclusions Dutch hospital discharge and cause of death registries are a valid source of data for subarachnoid haemorrhage, and show that the increased mortality rate in subarachnoid haemorrhage survivors is explained by increased risks for vascular diseases and death.