Background/Purpose:

Obesity, assessed as body mass index (BMI) ≥ 30 kg/m², is an important risk factor for osteoarthritis (OA). BMI depends only upon height and weight and therefore gives no insight in underlying causal pathways. The aim of this study was to investigate whether the association of BMI and OA in the hands, being non-weight bearing joints, can be explained by the amount of fat mass (FM) and the abdominal fat distribution.

Methods:

Data from participants of the NEO (Netherlands Epidemiology of Obesity) study, a population-based cohort of men and women aged 45-65 years with a BMI ≥ 27 kg/m² and a control group with a BMI < 27 kg/m², were used. BMI was assessed by measured weight in kg and length in cm. Waist-to-hip ratio (WHR) was calculated from waist and hip circumference measured in cm. FM was assessed in kg using bioelectrical impedance analysis. In 30% of participants MR imaging of the abdomen, at the level of the 5^th lumbar vertebra, was used to assess the relative amounts of visceral adipose tissue and subcutaneous adipose tissue in cm³. Hand OA was defined using the criteria of the American College of Rheumatology; pain was measured using a standardized questionnaire and physical examination of the hands was performed by trained research nurses. Pearson correlations were calculated between BMI and WHR and FM, visceral fat and subcutaneous fat. Odds ratios (OR) with 95% confidence intervals (CI) were calculated to associate BMI, WHR, FM, visceral fat and subcutaneous fat with hand OA using logistic regression analyses, stratified for sex and adjusted for age.

Results:

Data from 4562 participants (mean age 56 years, 48% male) were analyzed, including 425 controls with a BMI < 27 kg/m². Median BMI of the total study population was 30.3 kg/m² (IQR 28.4-33.1), median FM was 33.5 kg (IQR 27.5-40.8) and median WHR was 0.94 (IQR 0.88-0.99). Abdominal fat was measured in a subset of 1524 participants: median visceral fat was 122.8 cm³ (IQR 86.4-167.0) and median subcutaneous fat 306.7 cm³ (IQR 239.7-388.8). Hand OA was present in 8% of men and 21% of women. BMI was strongly correlated to FM (men r=0.89, women r=0.90) and subcutaneous fat (men r=0.72, women r=0.82), and moderately to visceral fat (men r=0.54, women r=0.57). WHR was moderately correlated to visceral fat (men r=0.59, women r=0.46), and only weakly to very weakly correlated to subcutaneous fat (men r=0.36, women, r=0.17). BMI was associated with hand OA in women (OR 1.02; 95% CI 1.00-1.04), but not in men. WHR was strongly associated with hand OA in men (OR 132.2; 95% CI 9.2-1901.9) and in women (OR 10.1; 95% CI 2.0-50.0). In both sexes, FM and subcutaneous fat were not significantly associated with hand OA. Visceral fat was associated with hand OA only in men (OR 1.005; 95% CI 1.001-1.009).

Conclusion:

BMI was associated with clinical hand OA only in women. FM and subcutaneous fat, which were strongly correlated with BMI, were not associated with hand OA in both men and women. In men, the WHR and visceral fat were associated with hand OA, suggesting involvement of visceral fat in the development of hand OA. In women, other underlying processes might play a role.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-association-of-fat-distribution-and-clinically-defined-hand-osteoarthritis-the-netherlands-epidemiology-of-obesity-study/