Hospital case volume is associated with mortality in patients hospitalized with subarachnoid hemorrhage

BACKGROUND: Prior studies have suggested that hospital case volume may be associated with improved outcomes after subarachnoid hemorrhage (SAH), but contemporary national data are limited. OBJECTIVE: To assess the association between hospital case volume for SAH and in-hospital mortality. METHODS: Using the Get With The Guidelines-Stroke registry, we analyzed patients with a discharge diagnosis of SAH between April 2003 and March 2012. We assessed the association of annual SAH case volume with in-hospital mortality by using multivariable logistic regression adjusting for relevant patient, hospital, and geographic characteristics. RESULTS: Among 31,973 patients with SAH from 685 hospitals, the median annual case volume per hospital was 8.5 (25th-75th percentile, 6.7-12.9) patients. Mean in-hospital mortality was 25.7%, but was lower with increasing annual SAH volume: 29.5% in quartile 1 (range, 4-6.6), 27.0% in quartile 2 (range, 6.7-8.5), 24.1% in quartile 3 (range, 8.5-12.7), and 22.1% in quartile 4 (range, 12.9-94.5). Adjusting for patient and hospital characteristics, hospital SAH volume was independently associated with in-hospital mortality (adjusted odds ratio 0.79 for quartile 4 vs 1, 95% confidence interval, 0.67-0.92). The quartile of SAH volume also was associated with length of stay but not with discharge home or independent ambulatory status. CONCLUSION: In a large nationwide registry, we observed that patients treated at hospitals with higher volumes of SAH patients have lower in-hospital mortality, independent of patient and hospital characteristics. Our data suggest that experienced centers may provide more optimized care for SAH patients.