Climate is associated with prevalence and severity of radiographic hand osteoarthritis

The aim of this study was to evaluate whether geographic location and climatic factors are associated with prevalence and severity of radiographic hand osteoarthritis (OA) in several samples of the same ethnicity. The total sample included 2079 ethnic Russians (900 males and 1179 females), belonging to 7 samples from different geographic locations in the former USSR. Places of residence were characterized by latitude, longitude, altitude and climatic parameters (mean temperatures, humidity, and daylight duration of January and July). Radiographs of the left hand were obtained from each individual. Osteoarthritis (OA) was evaluated in 14 hand joints according to Kellgren and Lawrence's grading system. OA was characterized by the presence of at least one affected joint and its severity by the number of affected joints (NAJ). Statistical analysis included prevalence estimation, polynomial and logistic regressions, ANOVA and correlation analyses. Prevalence of hand OA and NAJ were significantly associated with latitude and altitude and with most climatic parameters (except the inter-seasonal temperature amplitude and the mean atmospheric pressure of January and July). The highest correlations of hand OA prevalence were found with altitude (r=0.29, p<0.001), annual precipitation (r=-0.26, p<0.001) and the mean temperatures of July (r=0.26, p<0.001). The highest correlations of NAJ were found with altitude (r=0.51, p<0.001), mean humidity in January (r=-0.44, p<0.001) and the mean day duration in January (r=0.0.37, p<0.001). The present study demonstrates that the differences in prevalence and severity of radiographic hand OA among Russian samples are most likely dependent on climatic conditions in the place of residence.