Combined associations of obesity and physical activity with pain, fatigue, stiffness and anxiety in adults with spondyloarthropathies: UK Biobank study

Objective: Inflammatory spondyloarthropathies are associated with pain, fatigue, stiffness and anxiety. The National Institute for Health and Care Excellence and the EULAR provide limited lifestyle guidance for managing symptoms with inflammatory spondyloarthropathies. We investigated the combined associations of obesity and physical activity with symptom severity in inflammatory spondyloarthropathies.

Methods: The relationship between BMI, physical activity and symptom severity (spinal and general pain, fatigue, anxiety, mobility) was examined in people with ISpAs (n = 1577). BMI categories were normal weight (18.5-24.9 kg/m²), overweight (25.0-29.9 kg/m²) and obese (≥30 kg/m²). Physical activity was assessed via the International Physical Activity Questionnaire (low < 600 metabolic equivalent of task (MET)-min/week, moderate ≥ 600 METs, high ≥ 3000 METs). Statistical models adjusted for confounders, including medication, estimated the likelihood (odds ratios, OR) of higher symptom severity across BMI and physical activity categories.

Results: Overweight and obesity, compared with normal weight, were linked to higher severity of all symptoms, with stronger associations for obesity (OR ≥ 2.34, P < 0.001) than overweight (OR ≥ 1.37, P ≤ 0.032). Moderate activity, compared with low, was associated with lower severity of all symptoms (OR ≤ 0.77, P ≤ 0.032). High activity, compared with low, was associated with lower severity of fatigue, anxiety and mobility issues (OR ≤ 0.74, P ≤ 0.029), but associations with spinal and general pain were not significant (OR ≤ 0.80, P ≥ 0.056). No BMI-by-physical activity combinations were detected, indicating physical activity benefits all BMI groups to a similar extent.

Conclusion: National Institute for Health and Care Excellence and EULAR guidance for inflammatory spondyloarthropathies should emphasize maintaining a normal weight. Moderate physical activity is optimal for reducing symptom severity and should be promoted in lifestyle guidance.