A Retrospective Analysis of Surgical, Patient, and Clinical Characteristics Associated with Length of Stay Following Lumbar Spine Surgery
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Background: Elective spine surgeries utilize significant hospital resources. Postoperative hospital length of stay (LOS) requires substantial nursing, nutritional, social, administrative, and overhead resources, thus contributing greatly to the costs of institutional care. Previous studies have identified several pre-, intra-, and post-operative factors associated with increased LOS following elective spine surgery; however, findings are not consistent between studies, and research has not been done in a Nova Scotian setting. Objectives: 1) To describe the distribution of the demographic, clinical, operative, and postoperative characteristics among patients undergoing elective lumbar spine surgery for single- and two-level degenerative conditions at a Nova Scotian quaternary care institution between October 2014 to October 2016. 2) To describe how the demographic, clinical, operative, and postoperative characteristics are independently associated with LOS among the study population. Methods: We conducted a retrospective cohort study using data collected at the Halifax Infirmary. The sample included consecutive patients (> 18 years of age) who underwent single- or two-level elective lumbar spine surgery for degenerative conditions between October 2014 to October 2016 at a single institution by one of two orthopedic spine surgeons. Potentially eligible patients were identified using International Classification of Diseases ninth revision codes. We reviewed patients’ electronic medical charts and extracted information on demographic, clinical, and operative characteristics that we identified in studies from a systematic literature search. We collected and considered the following factors for inclusion in the statistical model: preoperative factors (sex, age, BMI, revision surgery, American Society of Anaesthesiology class, Charlson comorbidity index, hemoglobin level, narcotic-, antidepressant-, and neuroleptic-use, initial diagnosis, workers’ compensation claim), operative factors (analgesics, transfusion, blood loss, surgical case time, surgery performed, complications, operating surgeon), and postoperative factors (hemoglobin level and transfusion). The outcome of interest was LOS, calculated as the number of days from the date of surgery to the date of discharge. We used descriptive statistics to summarize the data. We used multiple quasi-Poisson regression to describe the characteristics independently associated with LOS. We stratified by surgery group when feasible to explore heterogeneity within the study population. Results: A total of 473 patients met inclusion criteria. The average age of patients was 59.6 years (95% confidence interval: [58.3, 61]). The median LOS was 3.0 days (Interquartile range (IQR) = 1-4) for the entire population, 4.0 days (IQR = 3-6) for 1-level transforaminal lumbar interbody fusion (TLIF) patients, 0 days (IQR = 0-1) for discectomy patients, and 2.0 days (IQR = 1-4) for laminectomy patients. Factors that were statistically significantly associated with LOS in adjusted analyses were age, BMI, preoperative antidepressant use, surgery group, long-acting intraoperative analgesics, operating surgeon, and postoperative blood transfusion. Stratified multivariable analysis showed effect modification by surgery group. Surgery group had the strongest association with LOS (RR > 3), followed by postoperative blood transfusion (RR > 1.5), intraoperative analgesics (RR < 1.5), and intraoperative complications (RR < 1.5). Conclusions: LOS following elective lumbar spine surgery for degenerative conditions is associated with several patient, clinical, and surgical factors and is highly dependent on the type of surgical procedure performed. These findings provide preliminary evidence for future research to develop and test a predictive model for LOS and may contribute to quality improvement. The results also provide evidence for future research to focus on more homogenous populations and include prospective, confirmatory studies.