Background: Overweight and obesity are well-known risk factors for osteoarthritis (OA) in weight-bearing joints. However, the role of increased body mass index (BMI) and waist circumference in OA of the non-weight-bearing joints is more controversial. Few hand OA studies have explored the associations between increased BMI/waist circumference and pain.
Objectives: The aim of this study was to explore whether BMI and waist circumference were associated with self-reported pain in the hands, feet, knees and hips as well as pain sensitization in persons with hand OA. Further, we examined whether synovitis could partly explain the association between BMI/waist circumference and pain, due to a low-grade inflammatory state in overweight persons.
Methods: The Nor-Hand study is an observational study of 300 participants with hand OA. We measured their height and weight in addition to their waist circumference. Participants completed Numeric Rating Scales (NRS) (0-10) about pain during the last 24 hours in their hands and feet, in addition to the Western Ontario and McMaster Universities OA Index (WOMAC) knee/hip pain subscale (0-20). Pressure pain thresholds (PPTs) (kg/cm2) were measured at both a painful and a non-painful interphalangeal joint of the hand, the left distal radioulnar joint and at the tibialis anterior and trapezius muscles. Temporal summation (TS) was measured with a weighted probe that was tapped 10 times at the left distal radioulnar joint. We considered TS to be present if the pain rating increased by ≥2 (i.e., >smallest detectable change) points on the NRS during the test. Ultrasound was used to score grey-scale synovitis on 0-3 scales in a total of 30 joints in the hands, 26 joints in the feet and the bilateral knees. We evaluated the relation of BMI and waist circumference to the pain scales and synovitis sum scores using linear regression, and to presence of pain sensitization assessed by PPT values and TS using linear and logistic regression, respectively. All analyses were adjusted for age, sex and education.
Results: The majority of participants were female (n=266, 89%), and the median (IQR) age was 61 (57-66) years. Persons with higher BMI and waist circumference reported higher pain intensity in their hands, feet, knees and hips (Table). Higher BMI and waist circumference were associated with lower PPTs at the tibialis anterior muscle (Table). No associations were found between BMI/waist circumference and PPTs at the other test sites (data not shown). Persons with higher BMI and waist circumference were more likely to have TS (Table). Increased BMI and waist circumference were not associated with more synovitis in the hands, feet or knees (data not shown).
Conclusion: In the Nor-Hand cohort, persons with higher BMI and waist circumference reported higher pain intensity in their hands, feet, knees and hips. This relation was not explained by higher levels of synovitis in the joints. However, the association may at least partly be driven by a higher prevalence of central pain sensitization in persons with higher BMI. Due to the cross-sectional study design we cannot conclude about causality.
Disclosure of Interests: Marthe Gløersen: None declared, Pernille Steen Pettersen: None declared, Tuhina Neogi Grant/research support from: Pfizer/Lilly, Consultant of: Pfizer/Lilly, EMD-Merck Serono, Novartis, Tore K. Kvien Grant/research support from: Received grants from Abbvie, Hospira/Pfizer, MSD and Roche (not relevant for this abstract)., Consultant of: Have received personal fees from Abbvie, Biogen, BMS, Celltrion, Eli Lily, Hospira/Pfizer, MSD, Novartis, Orion Pharma, Roche, Sandoz, UCB, Sanofi and Mylan (not relevant for this abstract)., Paid instructor for: Have received personal fees from Abbvie, Biogen, BMS, Celltrion, Eli Lily, Hospira/Pfizer, MSD, Novartis, Orion Pharma, Roche, Sandoz, UCB, Sanofi and Mylan (not relevant for this abstract)., Speakers bureau: Have received personal fees from Abbvie, Biogen, BMS, Celltrion, Eli Lily, Hospira/Pfizer, MSD, Novartis, Orion Pharma, Roche, Sandoz, UCB, Sanofi and Mylan (not relevant for this abstract)., Karin Magnusson: None declared, Hilde Berner Hammer Consultant of: Has received fees as consultant from Roche, AbbVie and Novartis., Speakers bureau: Has received fees for speaking from AbbVie, BMS, Pfizer, UCB, Roche, MSD and Novartis, Ida K. Haugen: None declared
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