Associations between body mass index and patient reported biopsychosocial outcomes among patients with spine pain.

Background: Obesity and spine pain are both highly prevalent and disabling conditions with complex, overlapping etiologies. While prior research has explored the link between body mass index (BMI) and low back pain (LBP), the multidimensional impact of elevated BMI on physical, mental, and social health among patients with spine disorders has not been sufficiently elucidated. Objectives: This study aimed to examine the associations between BMI and a range of patient-reported outcomes (PROs) including pain severity, opioid utilization and seven Patient-Reported Outcomes Information System Computer Adaptive Test (PROMIS-CAT) domains that measure physical, mental, and social health in individuals with spine-related pain. Methods: A retrospective analysis of patients presenting to a quaternary academic institution's spine center for evaluation was performed. Demographic, BMI and PRO data (PROMIS-CAT in the domains of Anxiety, Depression, Fatigue, Pain Interference, Physical Function, Sleep Disturbance, Ability to Participate in Social Roles and Activities, and Pain Intensity as well as self-reported opioid utilization) available in the medical record were retrieved. Relationships between BMI and PROMIS data were evaluated with pairwise Z-tests for proportions. Results: A total of 3756 patients were included in the analysis, and the distribution of BMIs was like that of the general US population. Compared to patients with Normal BMI, the Class II and III Obesity groups had a greater proportion of patients reporting Moderate and Severe Pain Interference, Physical Function impairments, and Ability to Participate in Social Roles and Activities. They also used opioid medications more often. There was no significant difference in Pain Intensity within the Pre-Obesity, Class I, II or III Obesity groups. However, No Pain was significantly more common than all other categories of pain severity within the No Obesity group. The No Obesity group also demonstrated decreased rates of Mild and Moderate Fatigue, Moderate and Severe Pain Interference, Mild and Moderate Physical Function, Mild and Moderate Ability to Participate in Social Roles and Activities, and opioid utilization when compared to those having Normal levels in each of those PROMIS domains or who did not use opioid medication. Conclusions: Complex and inconsistent relationships exist between BMI and biopsychosocial functioning among patients with spine pain. Generally, lower frequencies of impairment are present in non-obese patients (specifically for Fatigue, Pain Interference, Physical Function, Ability to Participate in Social Roles and Activities, and Pain Intensity) and higher frequencies of impairment are observed in patients with an elevated BMI (most consistently for Depression, Pain Interference, Physical Function Ability to Participate in Social Roles and Activities and opioid utilization).