Background Obesity is a strong risk factor for knee OA. Despite few longitudinal studies, it is often stated that obesity also increases the risk of hand OA. Smoking has been suggested to decrease the risk of OA, but results have been inconsistent. Alcohol may also induce a pro-inflammatory state with negative impact on joints.
Objectives To examine whether baseline obesity, smoking and alcohol intake are associated with more severe hand OA, and whether they are associated with hand OA development 4 years later.
Methods We included 1232 persons (1598 hands) from OAI without knee OA. Longitudinal hand x-rays were available for 994 persons. We focused on the distal (DIP) and proximal interphalangeal (PIP) joints. 406 (41%) persons (502 hands) had no radiographic DIP/PIP OA at baseline and were included in analyses on incident radiographic hand OA.
In cross-sectional analyses, we explored whether obesity, smoking and alcohol use were associated with more severe hand OA (KL sum score in DIP/PIP joints) at baseline. In longitudinal analyses, we studied whether baseline obesity, smoking and alcohol were associated with incident DIP/PIP OA in persons who had no OA in these joints at baseline. We used linear and logistic regression, respectively, using Generalized Estimating Equations to account for two hands per person. Each risk factor was evaluated in a separate model adjusted for age, sex and education.
Results Mean (SD) age was 58.4 (8.9) years, and 58% were women. Mean (SD) BMI was 26.8 (4.5) and 22.5 (2.9) kg/m2 at baseline and age 25, respectively. Alcohol use was reported by 83%, and the majority had <1 drink/week (37%). Current and former smoking was reported by 9% and 41%, respectively, and mean (SD) pack-years in cigarette smokers were 20.0 (18.6).
In cross-sectional analyses, a statistically significant association was found between 1–3 alcoholic drinks/week and KL sum score (B=1.55, 95% CI 0.42–2.67), but no dose-response relationship was found. No associations were found for obesity (Table) or smoking (data not shown).
Incident hand OA was found in 82/502 (16%) hands. We found higher odds of incident hand OA in current smokers (OR=2.20, 95% CI 1.02–4.77), but no dose-response relationship was found for smoking pack-years. Obesity (Table) and alcohol use (data not shown) did not increase the odds of developing hand OA.
Conclusions In contrast to a common belief that obesity is associated with increased risk of hand OA, we did not find any statistically significant associations with hand OA for neither measures of overweight/obesity. Furthermore, alcohol use was not associated with increased risk of hand OA. An unexpected association was found between current smoking and the development of hand OA, but the lack of a dose-response relationship between smoking pack-years and incident hand OA and no associations in cross-sectional analyses suggest that this may be a chance finding.
Disclosure of Interest None declared
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