Body size changes and social determinants: Effects on rheumatoid arthritis, complications, and life expectancy in middle-aged and older adults

<p>Little is known about the combined effects of body size changes and social determinants of health (SDOHs) on rheumatoid arthritis (RA). In this study, we assessed these effects on (1) the incidence and age at onset of RA; (2) complications after RA diagnosis; and (3) life expectancy in 302,239 middle-aged and older adults from the UK Biobank. Childhood body size data at age 10 were collected through a questionnaire. Adulthood body size was assessed using body mass index (BMI), the waist‒to‒hip ratio (WHR), and the waist‒to‒height ratio (WHtR). The SDOHs were constructed with 20 items, with each item dichotomized into advantaged and disadvantaged levels. Cox proportional hazard models and life tables were applied to calculate adjusted hazard ratios (HRs) and predict life expectancy. During a median follow-up period of 12.5 years, 3,649 participants developed RA. Adverse body size changes, particularly those leading to obesity in adulthood BMI or high WHR/WHtR in adulthood, were associated with an increased risk of RA. These risks were further amplified by unfavorable SDOHs, with hazard ratios ranging from 2.18–2.92. These interactive effects were consistently associated with an elevated risk of RA onset across age groups and post-RA complications. Notably, individuals with unfavorable SDOHs experienced the shortest life expectancies compared with those with favorable SDOHs across all body size change groups. In conclusion, adverse body size changes and unfavorable SDOHs are significantly associated with an increased risk of new-onset and age at onset of RA, post-RA complications, and reduced life expectancy.</p>