The Impact of Comorbidity Burden on Complications, Length of Stay, and Direct Hospital Costs after Minimally Invasive Transforaminal Lumbar Interbody Fusion.

STUDY DESIGN: Retrospective Cohort OBJECTIVE.: To determine if comorbidity as determined by Charlson Comorbidity Index (CCI) is associated with inpatient complication rate, length of stay (LOS), or direct hospital costs after minimally-invasive transforaminal lumbar interbody fusion (MIS-TLIF).

SUMMARY OF BACKGROUND DATA: In the spine literature, comorbidity burden has been associated with an increased risk for complications, prolonged LOS, and greater hospital costs. Few studies have investigated the influence of comorbidity burden on these outcomes in minimally-invasive spine surgery populations.

METHODS: A prospectively-maintained surgical registry of patients undergoing primary, single-level MIS-TLIF was retrospectively reviewed. Patients were stratified by CCI and tested for association with preoperative demographics and perioperative characteristics using chi-squared analysis or one-way analysis of variance for categorical and continuous variables, respectively. Complication rates, LOS and direct hospital costs were compared between groups were using a one-way analysis of variance.

RESULTS: 298 patients were included. 19.8% had a CCI of 0, 41.3% had a CCI of 1-2, 27.2% had a CCI of 3-4, and 11.7% had a CCI ≥ 5. Elevated CCI was associated with older age, smoking, and insurance status. Elevated CCI was significantly associated with a greater total inpatient complication rate. Regarding LOS and total direct hospital costs, there were no associations identified. However, elevated CCI was associated with greater costs accrued in the intensive care unit, laboratory costs, and cardiology-related costs.

CONCLUSIONS: Greater comorbidity burden as reflected by higher CCI scores as a reflection of comorbidity burden was associated with increased postoperative complication rates following primary, single-level MIS-TLIF. However, this did not lead to prolongations in hospital stay or increased total direct hospital costs. This lack of association may suggest that the limited tissue trauma and operative exposure utilized in minimally invasive approaches may limit the utility of CCI as a predictor of surgical outcomes and costs.

LEVEL OF EVIDENCE: 4.