Decrease in handgrip strength in rheumatoid arthritis (RA): is there a sex-related difference?

Rheumatoid arthritis occurs two to three times more often in women than in men and it has been less studied in men. The results of gender influence on clinical course of the disease are contradictory. The aim of this study is to determine the difference in handgrip strength between female and male RA patients in comparison to healthy individuals. The study included 100 RA patients and 100 healthy individuals (50% were male in both groups). Handgrip strength was measured in both hands using a dynamometer. A two-way ANCOVA was used to analyse the data and age was included in the study as covariate. The results show that both male and female RA patients have lower handgrip strength compared to healthy individuals. The analysis of gender and disease interaction has shown that male RA patients have lower handgrip strength than female RA patients in comparison with the healthy group, age adjusted. This interaction is evident and statistically significant in both right hand (F 1, 195) = 14.62; p < 0.01) and left hand (F 1, 195) = 20.54; p < 0.01). The common-language effect size has shown that there is 92% (right hand) and 93% (left hand) chance that male individual will have stronger handgrip than his female counterpart. In RA patients, there is 77% chance for both hands that male will have stronger handgrip. Men and women with RA have significantly lower handgrip strength compared to healthy individuals and the difference is more pronounced in men which was not previously observed in the literature.