Does body mass index mediate the relationship between socioeconomic position and incident osteoarthritis?
Published on Jul 1, 2022in Seminars in Arthritis and Rheumatism
· DOI :10.1016/j.semarthrit.2022.152063
• What is already known about this subject? • There are social inequalities in the prevalence of osteoarthritis (OA), but longitudinal studies assessing inequalities in the onset of disease are lacking • Obesity is an established risk factor for OA • What does this study add? • Lower socioeconomic position (SEP), measured through education, occupation, income and wealth, and obesity at baseline are associated with incident OA • The results suggest that body mass index mediates the relationships between lower SEP and incident OA • How might this impact on clinical practice or future developments? • 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/m 2 ) 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, 2,369 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<0.001) and the direct effect was not significant (β=0.004, p=0.212). : Strategies to reduce social inequalities and obesity prevalence may help to reduce OA risk.