Size of Ruptured Intracranial Aneurysms Is Decreasing

Background and Purpose— Decrease in the incidence of subarachnoid hemorrhage over the past decades has been related to decreased smoking rates, especially among <50-year-old people. We studied whether these epidemiological changes are reflected in changes in the size and location of ruptured intracranial aneurysms (RIAs). Methods— We identified consecutive patients admitted to a nonprofit academic hospital with saccular RIAs between 1989 and 2008. We averaged and analyzed mean sizes of RIAs in 4-year admission groups. In statistical analysis, we used the χ 2 test for categorical variables and the Kruskal–Wallis test to assess differences between continuous and categorical variables. For linear trend assessments, we used the linear-by-linear association and ANOVA tests. Results— Of 2660 consecutive patients (59% women) with RIAs, 1176 (44%) were <50 years on admission. In people <50 years, the averaged annual mean size of RIAs decreased 16% from 9.2 mm in 1989 to 1992 to 7.7 mm in 2005 to 2008 in women and 13% (from 9.3 to 8.1 mm) in men (decreasing linear trend; P =0.001). RIA sizes did not change in 50-year-old or older patients, whereas the proportion of posterior circulation RIAs almost tripled to 13%, also with a linear relationship ( P <0.001). Conclusions— The size of RIAs seems to be decreasing among younger generations of hospital-admitted subarachnoid hemorrhage patients, whereas 50-year-old and older subarachnoid hemorrhage patients have an increasing proportion of posterior circulation RIAs. These epidemiological changes are noteworthy, especially if they are universal and ongoing.