Association of risk factors with unfavorable outcomes after resection of adult benign intradural spine tumors and the effect of hospital volume on outcomes: an analysis of 18, 297 patients across 774 US hospitals using the National Inpatient Sample (2002-2011)

Abstract

OBJECT Because of the limited data available regarding the associations between risk factors and the effect of hospital case volume on outcomes after resection of intradural spine tumors, the authors attempted to identify these associations by using a large population-based database. METHODS Using the National Inpatient Sample database, the authors performed a retrospective cohort study that involved patients who underwent surgery for an intradural spinal tumor between 2002 and 2011. Using national estimates, they identified associations of patient demographics, medical comorbidities, and hospital characteristics with inpatient postoperative outcomes. In addition, the effect of hospital volume on unfavorable outcomes was investigated. Hospitals that performed fewer than 14 resections in adult patients with an intradural spine tumor between 2002 and 2011 were labeled as low-volume centers, whereas those that performed 14 or more operations in that period were classified as high-volume centers (HVCs). These cutoffs were based on the median number of resections performed by hospitals registered in the National Inpatient Sample during the study period. RESULTS Overall, 18,297 patients across 774 hospitals in the United States underwent surgery for an intradural spine tumor. The mean age of the cohort was 56.53 ± 16.28 years, and 63% were female. The inpatient postoperative risks included mortality (0.3%), discharge to rehabilitation (28.8%), prolonged length of stay (> 75th percentile) (20.0%), high-end hospital charges (> 75th percentile) (24.9%), wound complications (1.2%), cardiac complications (0.6%), deep vein thrombosis (1.4%), pulmonary embolism (2.1%), and neurological complications, including durai tears (2.4%). Undergoing surgery at an HVC was significantly associated with a decreased chance of inpatient mortality (OR 0.39; 95% CI 0.16-0.98), unfavorable discharge (OR 0.86; 95% CI 0.76-0.98), prolonged length of stay (OR 0.69; 95% CI 0.62-0.77), high-end hospital charges (OR 0.67; 95% CI 0.60-0.74), neurological complications (OR 0.34; 95% CI 0.26-0.44), deep vein thrombosis (OR 0.65; 95% CI 0.45-0.94), wound complications (OR 0.59; 95% CI 0.41-0.86), and gastrointestinal complications (OR 0.65; 95% CI 0.46-0.92). CONCLUSIONS The results of this study provide individualized estimates of the risks of postoperative complications based on patient demographics and comorbidities and hospital characteristics and shows a decreased risk for most unfavorable outcomes for those who underwent surgery at an HVC. These findings could be used as a tool for risk stratification, directing presurgical evaluation, assisting with surgical decision making, and strengthening referral systems for complex cases.

Keywords: ARF = acute renal failure; CAD = coronary artery disease; CCI = Charlson Comorbidity Index; CHF = congestive heart failure; CRF = chronic renal failure; DM = diabetes mellitus; DVT = deep vein thrombosis; HCUP = Healthcare Cost and Utilization Project; HVC = high-volume center; ICD-9-CM = International Classification of Diseases, Ninth Revision, Clinical Modification; LOS = length of stay; LVC = low-volume center; NF = neurofibromatosis; NF-1, -2 = NF Type 1, Type 2; NIS; NIS = National Inpatient Sample; National Inpatient Sample; PE = pulmonary embolism; PVD = peripheral vascular disease; SCT = spinal cord tumor; intradural spine tumors; spine surgery; unfavorable outcomes.