Risk Factors Associated With 30-day Readmissions After Instrumented Spine Surgery in 14,939 Patients 30-day readmissions after instrumented spine surgery

Study Design. A retrospective review of instrumented spine registry from an integrated US healthcare system. Objective. Investigate the 30-day readmission rate and risk factors after instrumented spine surgery. Summary of Background Data. Published readmission rates range from 2% to over 20%. We were interested in learning which patients were at greatest risk, when did readmissions occur, and why. Method. 30-day readmission rates were determined for 14,939 patients after an index spine procedure between 1/2009 and 3/2013. Data were analyzed with descriptive statistics, univariate, and multivariate logistic regression analysis. Result. The average age of the cohort was 59 (SD = 13.4) and 52% were female. The 30-day readmission rate was 5.5% (821/14,939). The temporal pattern for readmission was: 17% (140) at week 1, 48% (394) at week 2, 72% (591) at week 3, and 100% (821) at week 4. The leading causes were wound complications (infection, hematoma, dehiscence, seroma), sepsis, pain management, pneumonia, and pulmonary emboli/deep venous thrombosis. In a multivariate model, readmission risk factors were: malignancy (OR 2.99, 95% CI: 1.56, 5.73), operative time more than 400 minutes (OR 2.59, 95% CI: 1.66, 4.02), operative time 300-399 minutes (OR 2.33, 95% CI: 1.54-3.52), hospital stay 6-10 days (OR 2.03, 95% CI: 1.31-3.14), hospital stay more than 10 days (OR 1.85, 95% CI: 1.1, -3.08), surgical complications (OR 1.67, 95% CI: 1.18, 2.36), operative time 200-299 (OR 1.52, 95% CI: 1.04, 2.22), depression (OR 1.48, 95% CI: 1.14, 1.93), rheumatoid arthritis (OR 1.45, 95% CI: 1.05, 2.01), deficiency anemia (OR 1.30, 95% CI: 1.05, 1.61), and hypothyroidism (OR 1.29, 95% CI: 1.01, 1.64). Conclusion. Surgical complications (dural tear, deep infections, superficial infections, epidural hematoma), malignancy, lengthy operative times, and lengthy initial hospitalizations are all risk factors for 30-day readmission. These findings should be considered during preoperative assessment and surgical planning. Level of Evidence: 3