Incidence, treatment, and case-fatality of non-traumatic subarachnoid haemorrhage in the Netherlands

BACKGROUND Non-traumatic subarachnoid haemorrhage (SAH) is a devastating disorder and in the majority of cases it is caused by rupture of an intracranial aneurysm. No actual data are available on the incidence of non-traumatic SAH and aneursymal SAH (aSAH) in the Netherlands and little is known about treatment patterns of aSAH. Our purpose was therefore to assess the incidence, treatment patterns, and case-fatality of non-traumatic (a)SAH within the Dutch general population. METHODS Two population based data sources were used for this retrospective cohort study. One was the nationwide hospital discharge registry (National Medical Registration, LMR). Cases were patients hospitalized for SAH (ICD-9-code 430) in 2001-2005. The second source was the Integrated Primary Care Information (IPCI) database, a medical record database allowing for case validation. Cases were patients with validated non-traumatic (a)SAH in 1996-2006. Incidence, treatment, and case-fatality were assessed. RESULTS The incidence rate (IR) of non-traumatic SAH was 7.12 per 100,000 PY (95%CI: 6.94-7.31) and increased with age. The IR of aSAH was 3.78 (95%CI: 2.98-4.72). Women had a twofold increased risk of non-traumatic SAH; this difference appeared after the fourth decade. Non-traumatic SAH fatality was 30% (95%CI: 29-31%). Of aSAH patients 64% (95%CI: 53-74%) were treated with a clipping procedure, and 26% (95%CI: 17-37%) with coiling. CONCLUSION Non-traumatic SAH is a rare disease with substantial case-fatality; rates in the Netherlands are similar to other countries. Case-fatality is also similar as well as age and sex patterns in incidence.