Background: The contribution of osteoarthritis (OA) at the base of the thumb (BT) and digits 2-5 interphalangeal joints (IP) to disability in the hand has never been assessed.
Objectives: To evaluate and compare disability in patients with clinical hand OA and more severe symptoms at BT or IP.
Design: Observational, prospective, correlational.
Setting: Rheumatology and rehabilitation departments in two tertiary care teaching hospitals.
Participants: One hundred and sixteen patients (107 women, mean age 62+/-7 years) fulfilling the American College of Rheumatology criteria for OA in the hand, with more symptomatic BT (67 patients) or IP (49 patients).
Main outcome measure: Disability assessment with Cochin hand functional scale (CHFS) was the primary outcome. Assessment of impairment by the visual analog scale of pain (VAS pain), Ritchie articular index (RAI), modified Kapandji index (mKI), Kallman radiological classification and handicap assessment with visual analog scale (VASHd) was the secondary outcome. Group comparisons were assessed by use of Student's t-test for quantitative variables and Chi-square test for categorical variables. Results of the CHFS analysis were assessed by factorial analysis followed by Varimax rotation. Correlation between scores of disability, impairment, and handicap measures were calculated with use of Spearman rank correlation coefficient.
Results: Demographic data, disease duration, and level of global pain were similar between the BT and IP groups. The BT and IP groups did not differ significantly according to disability and handicap level (P=0.42 and P=0.94 for CHFS total score and VASHd, respectively). Factor analysis of the CHFS revealed similar results for the two groups of patients, especially for the first extracted factor. Disability scores correlated best with global hand pain (r=0.65) in the BT group and with RAI scores (r=0.71) in the IP group.
Conclusions: Disability and perceived handicap levels are comparable in clinical hand OA patients with more symptomatic BT or IP. These two groups should not be considered different during trials assessing treatments for hand OA when the primary outcome measure assesses disability.