Carotid intima-media thickness (cIMT) and diastolic blood pressure were found to have minimal involvement in the mediation of the association between body mass index (BMI) and osteoarthritis, according to a study published in Rheumatology.
This study was designed to examine the role of blood pressure, vessel wall stiffness (pulse wave velocity [PWV]), and subclinical atherosclerosis markers (cIMT and popliteal vessel wall thickness [pVWT]) as mediators of the association between obesity and osteoarthritis, using cross-sectional data from a subset of the Netherlands Epidemiology of Obesity study (n=6334).
Clinical hand and knee osteoarthritis were classified according to American College of Rheumatology criteria, and structural knee osteoarthritis, effusion, and bone marrow lesions were determined based on magnetic resonance imaging (MRI; n=1285). Ultrasonography was used to assess cIMT, knee MRI was used to evaluate pVWT (n=1285), and abdominal velocity-encoded MRI was used to assess PWV (n=2580) in subpopulations. Logistic regression analyses, adjusted for age, sex, and education, were used to assess associations between BMI and osteoarthritis, and blood pressure, cIMT, pVWT, and PWV were added to the model to estimate mediation.
The mean age of the cohort was 56 years, and 55% were women. In this cohort, 8% of participants had clinical hand osteoarthritis, 10% had clinical knee osteoarthritis, and 12% had structural knee osteoarthritis. BMI was found to be positively associated with all osteoarthritis outcomes.
cIMT was found to partially mediate the association between BMI and clinical hand osteoarthritis (mediation, 10.6%; 95% CI, 6.2-30.5%), structural knee osteoarthritis (mediation, 3.1%; 95% CI, 1.9-7.3%), and effusion (mediation, 10.8%; 95% CI, 6.0-37.6%). Diastolic blood pressure (2.1%; 95% CI, 1.6-3.0%) minimally mediated the association between BMI and clinical knee osteoarthritis, and PWV and pVWT were not found to mediate this association.
Study limitations include its cross-sectional design, the fact that MRIs were performed in a subpopulation, which reduced the number of participants in whom structural knee osteoarthritis could be measured and limited the number of pVWT and aorta PWV measurements.
“In our population, mediation of the association between BMI and osteoarthritis by preclinical cardiovascular disease measures was questionable,” the investigators commented. “Future research is warranted to further elucidate the association between cardiovascular disease and osteoarthritis, which perhaps could be explained by an alternative hypothesis such as shared pathophysiological processes.”
Loef M, van der Geest RJ, Lamb HJ, et al. Mediation of the association between obesity and osteoarthritis by blood pressure, vessel wall stiffness and subclinical atherosclerosis [published online December 21, 2020]. Rheumatology (Oxford). doi: 10.1093/rheumatology/keaa778