The relationship between obesity and patient-reported outcome measures in people with polymyalgia rheumatica.

Objective: To examine the association between obesity and patient-reported outcome measures (PROMs) in a primary care-based cohort of people with PMR.

Methods: The PMR Cohort Study recruited people with incident PMR from 382 general practices. Self-completed questionnaires (0, 12, 24 months) captured a range of PROMs for pain, stiffness, anxiety, depression, fatigue, function and quality of life, alongside data on BMI. People were categorized as underweight/normal weight (BMI < 25kg/m²), overweight (25-29.99 kg/m²) or obese (≥30 kg/m²). Piecewise, multilevel, linear mixed-effects regression models examined relationships between BMI categories and PROMs over time, adjusting for confounding variables. Chi-squared tests examined the relationship between obesity and glucocorticoid persistence.

Results: 644 people with PMR were included. At baseline, 33.9% were normal/underweight, 40.6% overweight and 25.5% obese. Compared with normal/underweight people, those with obesity had significantly worse scores for the following: pain and stiffness at 12 months; fatigue at 12 and 24 months; depression at baseline; physical function at all time points; and quality of life at baseline and 12 months. They also had significantly smaller improvements in stiffness (1.13 units on an 11-point numeric rating scale; P = 0.001) and physical function (0.14 units measured using the modified Health Assessment Questionnaire; P = 0.025) between 0 and 12 months. BMI categories did not relate to persistent glucocorticoid use at 12 months (P = 0.110) or 24 months (P = 0.166).

Conclusion: Obesity associates with poorer outcomes for a range of PROMs in people with PMR. Consideration should be given to providing weight management support to people with PMR and obesity.