Incidence of subarachnoid haemorrhage in the Aconcagua Valley, Chile: a community-based, prospective surveillance project.

Abstract

An epidemiological surveillance project was set up in Central Chile to detect cases of subarachnoid haemorrhage (SAH) and its incidence. Community-based prospective surveillance project carried out between 1 July 2000 and 30 June 2003, in the Aconcagua Valley in Central Chile. The authors ascertained all possible cases using multiple overlapping sources. Incidence rates were age-sex-adjusted. The authors identified 33 first-ever cases; 19 were women. The mean age (SD, range) was 50.7 (17.9, 16 to 82). The incidence per 100,000 age-sex adjusted to the world population was 5.1 (4.4 men, 5.6 women). The 30-day case-death rate was 54.5% (95% CI 38.0 to 70.2), and the prehospital death rate 21.2% (95% CI 10.7 to 37.7). The incidence rate in Aconcagua is notably similar to that reported previously in Northern Chile and lower than in many high-income western populations. The lower incidence rates found in these two Chilean populations might be due to their younger age. A trend towards a higher 30-day case-death rate found in Central Chile is possibly associated with its higher rurality and therefore lesser accessibility to preventive measures and medical care.