Do Patients with Elevated BMI Have Worse Outcomes Based on PROMIS Scores Following TLIF?

Introduction: Obesity is commonly considered a risk factor for patients undergoing spine surgery. While various studies have explored the effects of body mass index (BMI) on clinical outcome measures, current literature examining the effects of BMI on patient reported outcome measures (PROMs) is lacking. This study aims to analyze the effects of patient BMI on pre- and post-operative Patient Reported Outcome Measurement Information System (PROMIS) T-Scores for patients undergoing transforaminal interbody fusion (TLIF) procedures.

Methods: A prospectively collected multi-institutional quality registry was retrospectively reviewed. Patients who received a TLIF were categorized as non-obese (BMI < 30), obese I (BMI 30–34.9), or obese II–III (BMI ≥ 35). PROMIS T-Scores for physical and mental health were collected at baseline, 3 months, and 12 months after surgery. Univariate analyses were performed to compare pre- and postoperative scores and score changes across the three groups.

Results: Of the 315 patients with PROMIS T-Scores, there were 142 non-obese, 102 obese I, and 71 obese II–III patients. The three groups had similar demographics, though obese patients were younger and more commonly diabetic. At baseline, non-obese patients averaged better PROMIS physical health T-Scores (36.7 ± 6.6) than obese I (34.8 ± 6.6, p = 0.053) and obese II–III (33.9 ± 6.2, p = 0.003) patients. By 3 months, average physical health T-Scores improved significantly in all groups (p < 0.001), with the non-obese group maintaining a better average T-Score (48.8 ± 7.7) than obese I (46.6 ± 7.4, p = 0.040) and obese II–III (45.3 ± 8.4, p = 0.015) patients. A similar trend was observed for PROMIS mental health T-Scores, with non-obese patients scoring better at baseline and follow-ups. Analogously, physical and mental health T-Score changes reflected similar benefit between groups at 3 and 12 months.

Conclusion : While BMI may influence baseline health status as reflected by preoperative PROMIS T-Scores, patients across all BMI indexes had similar improvements in their PROMIS T-Scores at 3 and 12 months following TLIF procedures.