Background: To determine the longitudinal construct validity of assessing hand OA progression on digital photographs over 7 years compared with progression determined from radiographs, clinical features and change in symptoms.
Methods: Participants were community-dwelling older adults (≥50 years) in North Staffordshire, UK. Standardized digital hand photographs were taken at baseline and 7 years, and hand joints graded for OA severity using an established photographic atlas. Radiographic hand OA was assessed using the Kellgren and Lawrence grading system. Hand examination determined the presence of nodes, bony enlargement and deformity. Symptoms were reported in self-complete questionnaires. Radiographic and clinical progression and change in symptoms were compared to photographic progression. Differences were examined using analysis of covariance and Chi-Square tests.
Results: Of 253 individuals (61% women, mean age 63 years) the proportion with photographic progression at the joint and joint group-level was higher, though not statistically significantly, in those with radiographic or clinical progression compared to those without. At the person-level, those with moderate photographic progression over 7 years had significantly higher summed radiographic and clinical scores after adjustment for baseline scores compared to those with no or mild photographic progression. Similar findings were observed for change in symptoms, although differences were small and not statistically significant.
Conclusion: Assessing hand OA on photographs shows modest longitudinal construct validity over 7 years compared with change in radiographic and clinical hand OA at the person-level. Using hand photographs for determining long-term change may be a reasonable alternative when hand examinations and radiographs are not feasible.