Objectives. To investigate factors associated with joint damage in early RA, and how comorbid OA might influence patient assessment and outcomes.
Methods. Baseline radiographs of hands and feet from 512 participants in the Early RA Network cohort, and after 3 (±1) years, 166 of those participants yielded complete scores for RA [erosions, joint space narrowing (JSN)] and OA [JSN, osteophytes (OST)] using validated atlases. DAS28-P is the proportion of DAS28 attributed to patient-reported factors. Adjusted odds ratios were calculated using logistic regression.
Results. OA was common at baseline in early RA (40% hand and 48% foot) and associated with RA radiographic score. Higher baseline RA scores were associated with increasing age and ESR, and lower DAS28-P. OST scores were associated with higher age. DAS28 and patient-reported outcomes improved, whereas RA and OA radiographic scores deteriorated by follow-up. Erosive progression was predicted by higher baseline erosions, female gender, better mental health and lower DAS28-P. Hand OST progression was predicted by baseline OST scores. Inflammatory disease activity was associated with erosive, but not with OA progression. Baseline hand OA predicted worse physical function at follow-up, but radiographic progression did not explain changes in patient-reported outcomes.
Conclusion. OA is a common comorbidity that might confound radiographic and clinical assessment, but does not fully explain erosive progression or patient-reported outcomes in early RA. Early RA management should address psychosocial factors and comorbidities, as well as joint inflammation.