The relationship of primary hand osteoarthritis with serum leptin levels and body composition in women

Leptin is an adipose tissue hormone which plays a role in the pathogenesis of osteoarthritis (OA). Hand joints are an ideal target for investigating the effect of fat tissue and leptin hormone in the pathogenesis of obesity-associated OA, since they are not weight-bearing. İn this study we aimed to investigate the relation between serum levels of leptin and body composition with hand OA in middle age and older women. Fifty-one patients with symptomatic hand OA according to the American College of Rheumatology (ACR) clinical criteria and 46 healthy controls were included. Demographic data, anamnesis, and laboratory findings of patients and control groups were recorded. An 8-h fasting blood serum were collected for measurement of leptin plasma concentrations by enzyme-linked immunosorbent assay (ELISA). Body weight (kg), height (m), waist circumference (cm), and hip circumference (cm) were measured for all participants. Bioimpedance analyzer (Tanita MC 780 segmental body composition analyzer) was used for body composition measurement. Body mass index (BMI) (kg / m2), waist hip ratio, muscle mass (kg), muscle percentage, fat mass (kg), fat percentage, truncal fat mass (kg) and truncal fat percentage were recorded. Before the statistical analysis, the patients and the control group women were divided into 4 groups according to their BMI: normal weight (BMI = 18,5 to 24,99 kg/m2), overweight (BMI = 25 to 29,99 kg/m2), obese (BMI = 30 to 34,99 kg/m2), and very obese (BMI ≥ 35 kg/m2). Logistic regression analysis was performed to evaluate association of hand OA with leptin, waist circumference, waist hip ratio, fat percentage regardless of other variables. There was no statitistically significant difference in serum leptin levels between the patient and control group (p = 0,414). Serum leptin levels were lower in the patients than the controls in normal weight group(p=0,028); there was no difference between patient and control groups in the overweight, obese and very obese women, (respectively p= 0,282 , 0,613 , 0,234,). We found no statistically significant association between serum leptin and hand OA when assessed independently from age, BMI, and presence of OA in other joints (r = 1,048 p = 0,3761). There was a significant correlation between waist circumference and waist hip ratio and hand OA (respectively r = 1,362 p = 0,0348, r = <0,001 p = 0.0048). However, there was no correlation with BMI (r = 0,726 p = 0,3699). Fat percentages of patients were higher than control group (p = 0,049). Consequently, in contrast to some studies we did not find any evidence to support the hypothesis that high serum leptin levels is associated with hand OA. However, hand OA were associated with body composition measurements like fat percentage, waist circumference, and waist hip ratio. Therefore, further studies are needed to demonstrate the relationship between hand osteoarthritis and body fat distribution and to identify other adipose tissue hormones that may be effective in the pathogenesis of the disease. Key Words: Hand osteoarthritis, Leptin, Obesity, Body composition