Does body mass index mediate the relationship between socioeconomic position and incident osteoarthritis?

• Published in: Seminars in arthritis and rheumatism 2022-10, Vol.56, p.152063-152063, Article 152063
• Main Authors: Witkam, Rozemarijn, Gwinnutt, James M, Selby, David A, Cooper, Rachel, Humphreys, Jennifer H, Verstappen, Suzanne MM
• Format: Article
• Language: English
• Subjects: Mediation; Obesity; Osteoarthritis; Prospective study; Socioeconomic position
• ISSN: 0049-0172; 1532-866X
• DOI: 10.1016/j.semarthrit.2022.152063

•Obesity is an established risk factor for osteoarthritis (OA) and may mediate the relationship between a lower socioeconomic position (SEP) and incident OA.•The results suggest that body mass index mediates the relationships between lower SEP, measured through education, occupation, income and wealth, and incident OA.•Strategies to reduce social inequalities and obesity prevalence may help to reduce OA risk. To investigate associations of socioeconomic position (SEP) and obesity with incident osteoarthritis (OA), and to examine whether body mass index (BMI) mediates the association between SEP and incident OA. Data came from the English Longitudinal Study of Ageing, a population-based cohort study of adults aged ≥50 years. The sample population included 9,281 people. Cox regression analyses were performed to investigate the associations between SEP (measured by education, occupation, income, wealth and deprivation) and obesity (BMI ≥30 kg/m2) at baseline and self-reported incident OA. The mediating effect of BMI on the relationship between SEP and incident OA were estimated using Structural Equation Models. After a mean follow-up time of 7.8 years, 2369 participants developed OA. Number of person-years included in the analysis was 65,456. Lower SEP was associated with higher rates of OA (for example, hazard ratio (HR) lowest vs highest education category 1.52 (95% confidence interval (CI) 1.30, 1.79)). Obesity compared with non-obesity was associated with increased rates of incident OA (HR 1.37 (95% CI 1.23, 1.52)). BMI mediated the relationship between a lower SEP and OA (β = 0.005, p