Association between nail-fold capillary findings and disease activity in dermatomyositis

Although findings of nail-fold capillary changes and reduced red blood cell velocity in SSc patients are well established, studies in adult-onset DM patients are scarce. Our objective was to assess the changes and red blood cell velocity in finger nail-fold capillaries using nail-fold video capillaroscopy (NVC) in patients with adult-onset DM.

This study included 50 patients with adult-onset DM and 20 healthy subjects. A semi-quantitative rating scale was used to score capillaroscopy changes. Red blood cell velocity was evaluated using frame-to-frame determination of the position of capillary plasma gaps.

Thirty-seven (74%) patients showed the scleroderma NVC pattern. Patients with the scleroderma pattern exhibited elevated serum creatine kinase levels more frequently and increased visual analogue scale of muscle disease activity. Scores of loss of capillaries were associated with muscle and global disease activity, whereas scores of haemorrhages were associated with skin disease activity. However, NVC findings were not significantly associated with lung involvement. The scores of irregularly enlarged capillaries, haemorrhages and loss of capillaries were reduced after stabilization of disease activity by treatment. The mean red blood cell velocity was not significantly reduced in DM patients compared with healthy controls and was not changed by treatment.

Our results suggest that changes in nail-fold capillaries reflect disease activity in DM. Furthermore, the differences found in red blood cell velocity may reflect somewhat distinct microcirculation injuries in DM and SSc.