Krisht, Ali F.

Abstract Growth of unruptured intracranial aneurysms (UIAs) is a strong predictor of rupture. Clinical observations suggest that UIAs might grow faster after endovascular treatment than untreated UIAs. There are no head-to-head comparisons of incidence rates of UIAs so far. In this meta-analysis, we compared the incidence rates of growth of untreated UIAs and endovascularly treated UIAs. Methods: We searched PubMed, Embase and Google Scholar for relevant articles and conference abstracts in English, German or French from the inception of the databases to March 2020. We performed a meta-analysis by pooling the incidence rates for growth of aneurysms from natural history studies and endovascular treatment studies. Generalized linear models were used for multivariable adjustment for the prespecified confounders age, size and location. Results: 25 studies (10 describing growth in natural history and 15 reporting growth after endovascular therapy) with 6325 aneurysms were included in the meta-analysis. Median size of the aneurysm was 3.7 mm in the natural history studies and 6.4 mm in endovascular treatment studies (p = 0.001). The pooled incidence rate (IR) of growth was significantly higher in endovascular treatment studies (IR 52 per 1000 person-years, 95% Confidence Interval (CI) 36–79) compared to natural history studies (IR 28 per 1000 person-years, 95% CI 17–46), also after adjustment. Conclusion: The incidence rate of growth in endovascularly treated aneurysms was higher than in natural history studies. However, these results should be viewed in the light of high risk of bias of the individual studies and risk of ecological bias.