Get a grip on factors related to grip strength in persons with hand osteoarthritis: Results from the Nor-Hand study

Objective To compare levels of grip strength in persons with hand osteoarthritis (OA) with normative values, and examine how hand OA severity and other biopsychosocial factors are associated with grip strength. Methods Levels of grip strength across age groups were compared with normative values from the general population in sex‐stratified analyses using two‐sample T‐tests. Associations between radiographic hand OA severity (Kellgren‐Lawrence sum score) in different joint groups and grip strength of the same hand were examined in 300 persons from the Nor‐Hand study using linear regression. Analyses were repeated using markers of pain, demographic factors, comorbidities, psychological and social factors as independent variables. We adjusted for age, sex and body mass index. Results Persons with hand OA had lower grip strength than the general population, especially in persons below 60 years. In thumb base joints, increasing radiographic severity (range 0‐8) and presence of pain were associated with lower grip strength (beta=‐0.83, 95% CI ‐1.12, ‐0.53 and beta=‐2.15, 95% CI ‐3.15, ‐1.16, respectively). Negative associations with grip strength were also found for women, low education, higher comorbidity index and higher resting heart rate. Conclusion Persons with hand OA have lower grip strength than the general population. Our results support that studies on thumb base OA should include grip strength as an outcome measure. However, other biopsychosocial factors should also be considered when the grip strength is being interpreted, as other factors such as sex, socioeconomic factors, physical fitness, and comorbidities are negatively associated with grip strength