Statistical Analysis
REGRESSION, SECONDARY
For sample size calculation in the study planning phase, available retrospective studies were of questionable external validity due to their exceptionally low mortality. Data from the prospective LUMAS trial were not yet available.All statistics were performed with R version 4.1.0 (The R Foundation). Missing data were not imputed. Group differences of categorical variables were tested with the χIntention-to-treat analysis included all patients meeting all inclusion criteria and without exclusion criteria, regardless of their actual treatment. We performed additional sensitivity analysis in patients treated per protocol and as treated. Per-protocol analysis included all patients in the lumbar drain group with 480 mL or more drainage via lumbar route in the first 8 days and all patients in the standard of care group without a lumbar drain or, in case this was violated, receiving less than 480 mL of lumbar drainage in the first 8 days. The as-treated analysis was performed using all data according to the actual treatment, considering the patients being excluded in the per-protocol analysis in the corresponding other group.We used logistic regression for analysis of primary and secondary end points to allow for easy expansion to multivariate assessment. Odds ratios were transformed to risk ratios for more appropriate interpretation.Adjustment for multiple testing was not performed. Therefore, we regard all analysis beyond the primary end point as exploratory. Significance tests on secondary end points and other variables are provided to illuminate potential signals in the data and not for causal inference. A 2-sided 