Do patients with elevated BMI have worse outcomes based on 10-item Patient-Reported Outcomes Measurement Information System global health T-scores following transforaminal lumbar interbody fusion?

OBJECTIVE

Obesity is commonly considered a risk factor for patients undergoing spine surgery. While various studies have explored the effects of BMI on clinical outcome measures, current literature examining the effects of BMI on patient-reported outcome measures is lacking. This study aimed to analyze the effects of patient BMI on pre- and postoperative 10-item Patient-Reported Outcomes Measurement Information System (PROMIS-10) global health T-scores for patients undergoing transforaminal lumbar interbody fusion (TLIF).

METHODS

A prospectively collected multi-institutional quality registry was retrospectively reviewed. Patients who received a TLIF were categorized as nonobese (BMI < 30 kg/m2), class I obese (BMI 30-34.9 kg/m2), or class II or III obese (BMI ≥ 35 kg/m2). PROMIS-10 T-scores for global physical health (GPH) and global mental health (GMH) were collected at baseline and 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-10 T-scores, there were 142 nonobese, 102 class I obese, and 71 class II or III obese patients. The three groups had similar demographics, although obese patients were younger and more commonly had diabetes. At baseline, nonobese patients had significantly better mean PROMIS-10 GPH T-scores (36.7 ± 6.6) than class II or III obese (33.9 ± 6.2) (p = 0.003) patients. By 3 months, mean GPH T-scores improved significantly in all groups (p < 0.001), with the nonobese group (12.3 ± 8.1) demonstrating similar improvement to class I obese (12.0 ± 8.3, p = 0.7) and class II or III obese (11.0 ± 8.1, p = 0.3) patients. Likewise, mean GMH T-scores improved significantly in all groups by 3 months (p < 0.001), with the nonobese group (7.1 ± 8.7) demonstrating similar T-score improvement to class I (6.5 ± 8.1, p = 0.8) and class II or III (4.3 ± 8.0, p = 0.070) obese patients. Improvements in GPH and GMH T-score changes were maintained at 12 months and continued to show no significant variability between groups.

CONCLUSIONS

While BMI may influence baseline health status as reflected by preoperative PROMIS-10 T-scores, patients across all BMI indexes had similar improvements in their PROMIS-10 T-scores at 3 and 12 months following TLIF procedures.