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- Published on: 18 October 2021
- Published on: 18 October 2021The number of clinical events per variable in logistic regression analysis
Dear Editor,
I read with interest the paper by Pierot et al [1]. They conducted a prospective study to examine factors of delayed thromboembolic events in 335 patients after coiling of unruptured intracranial aneurysms. The number of delayed TEEs was 8. The adjusted odds ratios (95% confidence intervals) of autosomal dominant polycystic kidney disease and post-procedure aneurysm remnant at procedure completion for delayed TEEs were 27.3 (3.9 to 190.2) and 9.9 (1.0 to 51.3), respectively. They understand the lack of statistical power in the multivariate analysis and did not intend to examine the causal association. I present a comment regarding the number of events in logistic regression analysis.
The limitation in the total number of events for logistic regression analysis was simulated to improve statistical power [2]. In addition, Peduzzi et al. evaluated the effect of the number of events per variable (EPV) on the outcome in logistic regression analysis [3], concluding that the number of EPV less than 10 has some problems for the prediction of dependent variable. There is an opinion that EPV value less than 10 is also acceptable to evaluate the association by logistic regression analysis [4]. Pierot et al. observed 8 events, which was not appropriate for multivariate analysis even for examining the association instead of prediction in a prospective study. I think that wide ranges of 95% confidence intervals may reflect unstable estimates in a logistic regr...
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None declared.