Toenail abnormalities in rheumatoid arthritis patients are associated with radiographic damage and impact disability: a cross sectional study nested within a cohort.

Objectives: Cutaneous involvement is an extra-articular manifestation of rheumatoid arthritis (RA). This includes nail abnormalities, which are often overlooked. We described nail findings in RA patients currently attending an early arthritis cohort (n=145), and associated them with disease activity and/or damage, as well as patient-reported outcomes.
Methods: A standardised nail examination was performed in 122 patients (84.1% of the cohort), concomitant to the rheumatic assessment. Disability, quality of life and perceived nail-related health were also assessed. Nail findings and their location were recorded and classified according to standardised definitions. Logistic and linear regression models were used to investigate predictors of nail findings and to identify the impact of toenail findings on disability, which was evaluated with the HAQ. Patients consented to participate.
Results: Patients were primarily middle-aged females, with median follow-up of 9 years, and had disease under control. Most patients (62.3%) had at least one nail finding and these patients scored lower their nail-related health. The median (IQR) of findings/abnormalities per patient was 3 (2-5) and the number of nails affected per patient was 10 (2-12). Age (OR: 1.04, 95%CI: 1.007-1.074) and erosive disease (OR: 2.26, 95%CI: 1.1-5.1) were associated with nail findings. Toenail involvement was consistently associated with HAQ score out of normal range (OR=3.4, 95%CI=1.24-9.35, p=0.02). There was a linear association between the number of toenails affected and the HAQ score.
Conclusions: Nail abnormalities are common and heterogeneous findings in RA patients; they are associated with erosive damage and impact disability.