The Use of Patient-Reported Outcome Measurement Information System Physical Function to Predict Outcomes Based on Body Mass Index Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN Retrospective. OBJECTIVE To determine clinical outcomes in obese patients compared with non-obese patients utilizing Patient-Reported Outcome Measurement Information System Physical Function (PROMIS PF) following minimally invasive transforaminal lumbar interbody fusion (MIS TLIF). SUMMARY OF BACKGROUND DATA Although obesity is a risk factor for poor outcomes after spinal fusion, there has not been a study to evaluate clinical outcomes of obese patients utilizing the PROMIS PF survey. METHODS Patients undergoing MIS TLIF were stratified into three cohorts: non-obese (body mass index [BMI] ≤ 29.9 kg/m), obese I (BMI = 30.0-34.9 kg/m), and obese II-III (BMI ≥ 35.0 kg/m). Demographic and perioperative characteristics were compared using chi-squared analysis and linear regression. Change in PROMIS PF scores was calculated using paired t tests. Differences in PROMIS PF scores at each postoperative timepoint and changes in PROMIS PF from baseline were compared using linear regression. RESULTS One hundred eighty-six patients were included: 101 were non-obese, 41 were classified as obese I, and 44 were classified as obese II-III. Obese patients were more likely to be diabetic. Otherwise, no significant differences in demographic and perioperative characteristics were identified. Patients with higher BMIs reported significantly lower PROMIS PF scores at preoperative and all postoperative timepoints. However, patients experienced similar improvements through 6-month follow-up in PROMIS PF scores regardless of BMI. For the non-obese cohort, the change in the postoperative PROMIS PF score from baseline was significant at every postoperative timepoint. However, for the obese I and obese II-III cohorts, the change in the PROMIS PF score from baseline was significant at the 3-month and 6-month timepoints, but not at the 6-week timepoint. CONCLUSION Patients with higher BMI had lower preoperative PROMIS PF scores and experienced similar improvement in PROMIS PF scores in the postoperative period. This study established that PROMIS PF may be utilized to evaluate the recovery of obese patients following MIS TLIF. LEVEL OF EVIDENCE 3.