Simple Identification and Prediction of Outcomes Related to Comorbid Medical Diseases, as Assessed in 4263 Consecutive Neurosurgical Procedures

Introduction: Identification and optimization of modifiable medical comorbidities improve surgical outcomes. However, unnecessary workup for unmodifiable comorbidities may increase healthcare expenditures and delay intervention. No study in neurosurgery has yet isolated comorbid status from other patient-level variables. Here, we evaluate the Charlson Comorbidity Index (CCI) – a simple and cost-free measure of aggregate medical comorbidity – to predict outcomes from a common surgical procedure. To isolate CCI, we matched comorbid patients to healthy counterparts based on important, outcome-impacting characteristics.

Methods: In this IRB-approved trial, 4263 consecutive patients undergoing single-level, posterior-only lumbar fusion at a single academic medical center were prospectively enrolled and retrospectively analyzed. First, logistic regression estimated the univariate relationship between CCI and patient outcomes. Subsequently, Coarsened Exact Matching (CEM) generated exact demographic matches between patients with high comorbid status (CCI>6) and no medical comorbidities (matched n=524). Patients were matched 1:1 on characteristics including gender, race, BMI, and smoking status, among others. Outcomes were compared between exact-matched cohorts. Primary outcomes included surgical complications, discharge disposition, and 30- and 90-day risk of readmission, Emergency Department (ED) visit, reoperation, and mortality.

Results: Univariate regression of increasing CCI suggested an increased risk of non-home discharge, as well as 30- and 90-day readmission, ED visits, and mortality (all p< 0.05). Subsequent isolation of comorbidity between otherwise exact-matched cohorts demonstrated that high comorbid status does not affect readmissions, reoperations, or mortality; although high comorbidity was significantly associated with non-home discharge (OR=2.50, p< 0.001) and 30- and 90- day ED evaluation (OR=2.44, p=0.02; OR=2.29, p=0.008).

Conclusion : Comorbidity as estimated by CCI does not increase risk of short-term readmission, reoperation, or mortality after single-level spinal fusion for otherwise matched patients. These findings suggest that controlled trauma related to single-level, posterior lumbar fusion is well-tolerated regardless of comorbidity. Further study of CCI to guide preoperative decision-making is warranted.