Validity and factor structure of the AUSCAN Osteoarthritis Hand Index in a community-based sample

The AUStralian CANadian Osteoarthritis Hand Index (AUSCAN) is a self-report assessment of hand pain, stiffness, and function. Prior studies have examined its validity in small clinical samples and family-based samples. This study examined measurement properties of the AUSCAN in a large, community-based sample, extending knowledge about the scale's generalizability.

Participants (N=1730, mean age=61 years, 65% female, 30% African American) were enrolled in the Johnston County Osteoarthritis Project. We examined the internal consistency, construct validity, and factor structure of the AUSCAN among the total sample, as well as in subgroups according to gender, race, presence of hand pain, and presence of radiographic hand osteoarthritis (OA).

Internal consistency was high for the total scale and subscales among the full study sample and all subgroups (Cronbach's alphas=0.89-0.96). Construct validity was also supported, as grip and pinch strength were more strongly correlated with the AUSCAN function subscale than with the pain and stiffness subscales. Factor analysis showed that for the full sample and most subgroups, all pain items loaded on one factor (standardized regression coefficients 0.59-0.81) and all function items loaded on another (standardized regression coefficients 0.61-0.78), supporting the intended subscale structure of the scale. However, for African Americans, a different factor pattern emerged, with three function items loading on a factor with the pain items.

Results support the validity of the AUSCAN in a general sample of adults, as well as across demographic and clinical subgroups, although the subscale structures differed slightly by race.