Impact of body mass index on PROMIS outcomes following lumbar decompression
James W Nie1, Timothy J Hartman1, Eileen Zheng1
1Department of Orthopaedic Surgery, Rush University Medical Center, 1611 W. Harrison St., Suite #300, IL, 60612, Chicago, USA.
Background:
No studies have examined the impact of body mass index (BMI) on newer Patient-Reported Outcomes Measurement Information System (PROMIS) outcomes in patients undergoing lumbar decompression (LD).
Methods:
Patients undergoing LD with preoperative PROMIS measures were stratified into four cohorts: normal (18.5 ≤ BMI < 25 kg/m2), overweight (25 ≤ BMI < 30 kg/m2), obese I (30 ≤ BMI < 35 kg/m2), and obese II-III (BMI ≥ 35 kg/m2). Demographics, perioperative characteristics, and patient-reported outcomes (PROs) were obtained. PROs of PROMIS Physical Function (PROMIS-PF), PROMIS Anxiety (PROMIS-A), PROMIS Pain Interference (PROMIS-PI), PROMIS Sleep Disturbance (PROMIS-SD), Patient Health Questionnaire-9 (PHQ-9), Visual Analog Scale (VAS) Back Pain (VAS-BP), VAS Leg Pain (VAS-LP), and Oswestry Disability Index (ODI) were collected at preoperative and up to 2-year postoperative time points. Minimum clinically important difference (MCID) achievement was determined through comparison of previously established values. Comparison between cohorts were determined through inferential statistics.
Results:
A total of 473 patients were identified, with stratification of 125 patients in the normal cohort, 161 in the overweight cohort, 101 in the obese I cohort, and 87 in the obese II-III cohort. Mean postoperative follow-up time was 13.51 ± 8.72 months. Higher BMI patients had higher operative times, longer postoperative length of stay, and greater narcotic consumption (p ≤ 0.001, all). Patients with higher BMI (obese I, obese II-III) reported inferior preoperative PROMIS-PF, VAS-BP, and ODI scores (p ≤ 0.003, all). Postoperatively, obese I-III cohorts demonstrated inferior PROMIS-PF, PHQ-9, VAS-BP, and ODI scores at final follow-up (p ≤ 0.016, all). However, patients demonstrated similar postoperative changes and MCID achievement regardless of preoperative BMI.
Conclusion:
Patients undergoing lumbar decompression demonstrated similar postoperative improvement in physical function, anxiety, pain interference, sleep disturbance, mental health, pain, and disability outcomes independent of preoperative BMI. However, obese patients reported worse physical function, mental health, back pain, and disability outcomes at final postoperative follow-up. Patients with greater BMI undergoing lumbar decompression demonstrate inferior postoperative clinical outcomes.
