Fast track — ArticlesChanges in case fatality of aneurysmal subarachnoid haemorrhage over time, according to age, sex, and region: a meta-analysis
Introduction
In 1997, in a systematic review of case fatality rates reported after aneurysmal subarachnoid haemorrhage (SAH) in population-based studies published between 1965 and 1995, we found a non-significant reduction in the case fatality rate of 0·5% per year.1 Since publication of that systemic review, diagnostic and treatment strategies for SAH have advanced: the introduction of CT angiography has aided early detection of aneurysms; the use of nimodipine has been implemented at many centres after publication of a key trial in 1989;2 dedicated stroke units have been introduced;3 and endovascular coiling of ruptured aneurysms, which was introduced in the early 1990s,4 has substantially improved the prognosis of patients who reach hospital in a good or reasonably good condition and are eligible for such treatment.5
New population-based studies have been published since 1995, but whether the improved diagnostic and management strategies have led to a decrease in the case fatality of SAH in the general population is not known. Moreover, some of the new population-based studies were done in regions that were not covered in our first review. In the previous review, only a few studies included case morbidity and case fatality as outcome measurements. Because case morbidity is important, not only for the patients but also for their relatives and society in general, a more precise estimate would be useful.
We did a meta-analysis on population-based case fatality and functional outcome after SAH to assess whether case fatality had decreased, whether a more precise estimate of case morbidity could be obtained, and to report differences according to age, sex, and region.
Section snippets
Study selection
To find new population-based studies on SAH we used the same methods as we used in the previous review.1 We did an additional PubMed search from January, 1995, to July, 2007, with different combinations of the following key words: (“subarachnoid h[a]emorrhage”) and (“epidemiology” or “population” or “mortality” or “outcome” or “case fatality”) and (“1995/1/1”; “2007/7/1”); (“stroke”) and (“epidemiology” or “population” or “mortality” or “outcome” or “case fatality”) and (“1995/1/1”; “2007/7/1”)
Results
We identified 33 articles, 23 of which were published in 1995 or later, that covered 39 study periods9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41 between 1972 and 2003 (table 1).42, 43, 44 The median mid-calendar year of all studies was 1994. The studies were done in 19 countries in five continents (panel 2). Of the 21 studies that were included in the former review, 11 were excluded from the present
Discussion
Over the past three decades, case fatality rates after SAH have decreased, despite the age of the study population increasing. Because age is a predictor of poor outcome,45 we expected to find a greater decrease in case fatality after adjustment for age. However, a reduction in the point estimate for decrease in case fatality was found instead. This paradoxical finding can be explained by the inclusion of the Japanese studies in the meta-analysis.21, 24, 33 These studies were published in the
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