The Moderating Effect of Obesity on Cognitive-Behavioral Pain Treatment Outcomes

Objective. To assess the effects of body mass index on cognitive‐behavioral pain treatment outcomes for chronic low back pain. Design. Retrospective analyses of data from a clinical trial were performed, with body mass index used to divide patients into obese and non‐obese groups for comparison. Setting. VA medical center outpatient clinic. Patients. Veterans (N = 74) receiving outpatient care through the VA. Interventions. Delivery of a 10‐week cognitive‐behavioral pain treatment intervention. Outcome Measures. The Numerical Rating Scale (pain intensity), Roland Morris Disability Questionnaire (disability), Veteran's SF‐36 (health‐related quality of life), and Beck Depression Inventory (emotional functioning) were administered pre‐ and post‐treatment. Results. The study included 42 obese and 32 non‐obese participants, most of whom were male (89%). The average body mass index was 32.44 kg/m2, with average pain intensity rated as 6.59 out of 10. There were no pre‐treatment differences in outcome measures between the groups. Repeated measures ANOVAs revealed main effects of Time on all but one outcome (Mental Component score), indicating that the cognitive‐behavioral interventions were largely effective. However, Time–body mass index (BMI) group interactions revealed that non‐obese participants showed greater improvement following treatment than did their obese counterparts on measures of disability (P