Readmission rate after 2-level lumbar decompression: A propensity-matched cohort study comparing inpatient and outpatient settings

Study Design:Retrospective review of the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database years 2012-2015.Objective:Compare the 30-day readmission and postoperative major complications rates of 2-level lumbar decompression performed in the ambulatory and the inpatient settings.Summary of Background Data:In recent years, there is an increasing trend toward ambulatory spine surgery. However, there remains a concern regarding risks of readmission and postoperative morbidity after discharge.Methods:The ACS-NSQIP database from 2012 to 2015 was queried for adult patients who underwent elective 2-level lumbar decompression (CPT code 63047 accompanied with code 63048). A cohort of ambulatory lumbar decompression cases was matched 1:1 with an inpatient cohort after controlling for patient demographics, comorbidities, and complexity of the procedure. The primary outcome was the 30-day readmission rate. Secondary outcomes included a composite of 30-day postoperative major complications and hospital length of stay for hospitalized patients.Results:A total of 7505 patients met our study criteria. The ambulatory 2-level lumbar decompression surgery rate increased significantly over the study period from 28% in 2012 to 49% in 2015 (P<0.001). In the matched sample, there was no statistically significant difference in the 30-day readmission rate (odds ratio, 0.82; 95% confidence interval, 0.64-1.04; P=0.097) between the two cohorts; however, the ambulatory cohort had a lower 30-day postoperative major complication rate (odds ratio, 0.55; 95% confidence interval, 0.38-0.79; P=0.002).Conclusions:After 2-level lumbar decompression performed on inpatient versus outpatient basis, the 30-day readmission rate is similar. However, the 30-day postoperative complication rate is significantly lower in the ambulatory setting. The reasons for these differences need further exploration.Level of Evidence:Level III.