The effects of hospital and surgeon volume on postoperative complications after lumbar spine surgery

Study Design: Retrospective review. Objective: To determine the correlation of surgeon/hospital volume with complication/mortality rates and with in-hospital health care utilization in lumbar spine surgery. Summary of Background Data: Studies have shown improved outcomes in patients treated by high-volume surgeons and hospitals. To our knowledge, no studies evaluate this relationship for lumbar spine surgery. Methods: To evaluate the 1992-2005 data in the National Inpatient Sample, we used the International Classification of Diseases, ninth Revision, Clinical Modification (ICD-9-CM) codes for lumbar spine surgery to identify relevant hospitalizations. We assessed 232,668 hospitalization records listed as posterolateral lumbar decompression with fusion and/or exploration/decompression of the spinal canal. Annual surgeon and hospital volumes were stratified into quartiles via identifier codes. Patient demographics and comorbidity status were recorded for each group. Mortality and morbidity were primary endpoints. We used the Shapiro-Wilk test for normality for the distribution of variables; one-way analysis of variance to assess continuous measures; χ statistics for categorical measures; and logistic regression for the effect of procedure on the probability of morbidity and mortality, adjusting for confounding variables, including patient demographics. Logistic regression data were tabulated as odd ratios (ORs) and 95% confidence intervals (CIs) (statistical significance, P < 0.05). Results: When controlled for other variables, mortality was significantly lower in the highest volume hospitals (OR, 0.78; 95% CI 0.66 to 0.89) and among the highest volume surgeons (OR, 0.66; 95% CI 0.59 to 0.89) than in their lowest volume counterparts. The complication rate was slightly lower in the highest volume hospitals (OR, 0.94; 95% CI 0.81 to 0.99) and significantly lower among the highest volume surgeons (OR, 0.73; 95% CI 0.68 to 0.91) than in their lowest volume counterparts. Conclusion: The mortality and complication rates associated with lumbar spine surgery are lower when patients are treated by high-volume surgeons and hospitals.