Readmission Rates, Reasons, and Risk Factors in Elderly Patients Treated With Lumbar Fusion for Degenerative Pathology

STUDY DESIGN: Retrospective database review. OBJECTIVE: To determine readmission rates after 1 to 2 level, primary, elective lumbar spinal fusion surgery for degenerative pathology and elucidate risk factors that predict increased risk of 30-day readmission SUMMARY OF BACKGROUND DATA.: Early postoperative readmissions after spine surgery represent a significant source of increased cost and morbidity. As the elderly population represents a demographic with a growing need for spine surgery, readmissions within this population are of significant interest. METHODS: Medicare data (2005-2012) from an insurance database was queried for patients who underwent primary 1 to 2 level posterolateral lumbar spine fusion surgeries for degenerative lumbar pathology. After applying specific exclusion criteria to select for elderly patients (65-84 yr) undergoing mostly elective procedures, 52,567 patients formed the final study population. Readmission rates for medical, surgical, and all reasons were calculated within 30 days, 90 days, and 1 year postoperatively. Risk factors for medical, surgical, and all 30-day readmissions were also determined. RESULTS: Within 30 days, 90 days, and 1 year, 1510 (2.9%), 2776 (5.3%), and 6574 (12.5%) patients were readmitted, respectively. At 30 days, surgical diagnoses constituted 50.1% of all readmissions. Wound infection was the reason for readmission in 25.8% of all readmissions within 30 days. Diagnoses of chronic pulmonary disease (OR 1.41 95% CI 1.22-1.63), obesity (OR 2.20 95% CI 1.90-2.54), and positive smoking history (OR 1.33 95% CI 1.15-1.54) were associated with increased risk of surgical readmission. CONCLUSION: Elderly patients undergoing lumbar spine fusion experience 30-day, 90-day, and 1-year readmission rates of 2.9, 5.3, and 12.5% for both medical and surgical reasons. Surgical site infection and wound complications are the most common surgery-related reasons for readmission. Medical diagnoses are more predominant during later readmissions, highlighting the comorbidity burden present in elderly patients. LEVEL OF EVIDENCE: 4.