Objective
To determine whether an apparent association between hand osteoarthritis (OA) and adiposity is explained by the presence of OA at other joint sites.
Methods
Data from the Canadian Longitudinal Study on Aging, first cycle, comprehensive cohort, were used. Respondents age 45â85âyears (n = 18,279) were asked separate questions about doctorâdiagnosed OA in the hand, hip, or knee. Multinomial logistic regression was used to investigate the relationship between all combinations of hand, hip, and knee OA and body mass index (BMI) and waistâtoâheight ratio (WHtR).
Results
OA was reported by 34.6% of respondents, 28.0% with OA at >1 joint site. Hand OA was not significantly associated with BMI after accounting for OA at other joint sites, with similar findings for WHtR. All joint site combinations containing the knee were strongly associated with BMI, with odds ratios (ORs) ranging from OR 2.92 (95% confidence interval [95% CI] 2.53â3.37) for knee OA only with obesity class I to OR 9.98 (95% CI 7.12â13.88) for multiâjoint knee, hip, hand OA with obesity class II/III. BMI distributions including knee OA were broader and shifted to higher BMI levels than those for hand or hip OA.
Conclusion
Apparent associations between hand OA and BMI may be explained by concurrent OA at other joint sites. Recognizing that OA is a multiâjoint disease is crucial for studies of the associations of adiposity with OA in a particular joint, especially the hand. The association between knee OA and BMI appears to be distinct from those for OA at other joint sites.