Risk factors for 30-day reoperation and 3-month readmission: analysis from the Quality and Outcomes Database lumbar spine registry

OBJECTIVE The aim of this paper was to use a prospective, longitudinal, multicenter outcome registry of patients undergoing surgery for lumbar degenerative disease in order to assess the incidence and factors associated with 30-day reoperation and 90-day readmission. METHODS Prospectively collected data from 9853 patients from the Quality and Outcomes Database (QOD; formerly known as the N²QOD [National Neurosurgery Quality and Outcomes Database]) lumbar spine registry were retrospectively analyzed. Multivariate binomial regression analysis was performed to identify factors associated with 30-day reoperation and 90-day readmission after surgery for lumbar degenerative disease. A subgroup analysis of Medicare patients stratified by age (< 65 and ≥ 65 years old) was also performed. Continuous variables were compared using unpaired t-tests, and proportions were compared using Fisher's exact test. RESULTS There was a 2% reoperation rate within 30 days. Multivariate analysis revealed prolonged operative time during the index case as the only independent factor associated with 30-day reoperation. Other factors such as preoperative diagnosis, body mass index (BMI), American Society of Anesthesiologists (ASA) class, diabetes, and use of spinal implants were not associated with reoperations within 30 days. Medicare patients < 65 years had a 30-day reoperation rate of 3.7%, whereas those ≥ 65 years had a 30-day reoperation rate of 2.2% (p = 0.026). Medicare beneficiaries younger than 65 years undergoing reoperation within 30 days were more likely to be women (p = 0.009), have a higher BMI (p = 0.008), and have higher rates of depression (p < 0.0001). The 90-day readmission rate was 6.3%. Multivariate analysis demonstrated that higher ASA class (OR 1.46 per class, 95% CI 1.25-1.70) and history of depression (OR 1.27, 95% CI 1.04-1.54) were factors associated with 90-day readmission. Medicare beneficiaries had a higher rate of 90-day readmissions compared with those who had private insurance (OR 1.43, 95% CI 1.17-1.76). Medicare patients < 65 years of age were more likely to be readmitted within 90 days after their index surgery compared with those ≥ 65 years (10.8% vs 7.7%, p = 0.017). Medicare patients < 65 years of age had a significantly higher BMI (p = 0.001) and higher rates of depression (p < 0.0001). CONCLUSIONS In this analysis of a large prospective, multicenter registry of patients undergoing lumbar degenerative surgery, multivariate analysis revealed that prolonged operative time was associated with 30-day reoperation. The authors found that factors associated with 90-day readmission included higher ASA class and a history of depression. The 90-day readmission rates were higher for Medicare beneficiaries than for those who had private insurance. Medicare patients < 65 years of age were more likely to undergo reoperation within 30 days and to be readmitted within 90 days after their index surgery.