Effect of Incidental Durotomy on Cost and Length of Stay in Primary, Short, Posterior Lumbar Fusion for Lumbar Spinal Stenosis: An Analysis of 17,232 Cases

Abstract

Introduction The incidence of durotomy and its economic impact during primary short lumbar fusion is not well described. The purpose of this study was to determine the incidence of and factors associated with durotomy in primary one- or two-level lumbar fusions performed for lumbar spinal stenosis and its impact on cost and hospital resource utilization. Material and Methods The Nationwide Inpatient Sample (NIS), was queried using ICD-9 codes for all primary one- or two-level lumbar fusions performed in adults for lumbar spinal stenosis between 2009 and 2011; only elective cases without concurrent diagnoses of vertebral infection, fracture, or tumor were included. Chi-square and t-tests were used as appropriate to compare categorical and continuous variables, respectively. Multivariate regression analysis was performed to identify factors independently associated with incidental durotomy, as well as total hospital charges and costs, as well as length of stay (LOS). Results A total of 17,232 procedures performed were identified, of which 801 had an incidental durotomy (rate of 4.65%). The rate of dural tears in teaching hospitals (5.09%; 95% CI: 4.66–5.55) was significantly higher as compared with nonteaching hospitals (4.19%; 95% CI: 3.77–4.66) ( p = 0.006). Multivariate regression analysis revealed that the odds of experiencing a dural tear increased by 2% with each year of increasing age (unit odds 1.02; 95% CI: 1.01–1.03). Incidental durotomy was associated with a mean 1.40-day (95% CI: 1.22–1.59) increase in hospital stay, a mean $10,885 (95% CI: $6,592–$15,177) increase in total hospital charges, and a mean $3,873 (95% CI: $2,502–$5,242) increase in estimated total costs (all differ from no durotomy group with p < 0.0001). Conclusion In this large retrospective series, the rate of incidental durotomy during primary short lumbar fusion for LSS fell within the range of previously reported rates. We have identified increasing age and surgery in a teaching hospital as factors associated with higher rates of durotomy. These findings are important given the significant financial and health care resource costs associated with dural tears.