Multi-center pressure reactivity index temporal trajectories for predicting outcome in comatose subarachnoid hemorrhage patients.

Pressure reactivity index (PRx) is a surrogate for cerebral autoregulation and has been used for prognostication in aneurysmal subarachnoid hemorrhage (SAH). We examined patient-specific temporal courses of PRx and identified time thresholds that optimized the accuracy of PRx monitoring. Comatose patients with SAH from two Comprehensive Stroke Centers were identified and received continuous ICP and PRx recordings. Outcomes were dichotomized into "poor" versus "good" based on disposition and modified Rankin score. Smoothed PRx trajectories were created to generate "candidate features", looking at daily average PRx and cumulative first-order and second-order changes in PRx. "Candidate features" were used to perform penalized logistic regression analysis. Penalized logistic regression models that maximized specificity for poor outcome were iteratively generated and evaluated sensitivity changes over time. We evaluated 33 comatose SAH patients in this cohort. Average PRx trajectories for good and poor outcome groups diverged at post-ictus day 6. When targeting specificities ≥ 78.6% for poor outcome, sensitivities for predicting poor outcome maximized to 70% (± 7%) at post-ictus day 8 and remained between 55% and 65% for the remainder of the monitoring period up to day 23. Area under curve-receiver operating characteristic (AUC-ROC) curves consistently demonstrated AUC-ROC > 0.71 after post-ictus day 8 (maximum AUC-ROC 0.78 at day 8). We found that when using PRx time-thresholds for predicting poor outcome in comatose SAH patients, prognostication with PRx was maximized at post-ictus day 8. Longer PRx monitoring did not improve predictive power. Further study is required to validate these findings.