Statistical definition of nail fold capillary pattern in patients with systemic sclerosis

Image analysis of videographs of nail fold capillaries was performed in patients with systemic sclerosis (SS), and the capillary patterns were defined by canonical discriminant analysis. Forty-eight of 55 SS patients were significantly differentiated from patients with systemic lupus erythematosus and normal controls. Normal controls and patients with systemic lupus erythematosus showed identical nail fold capillary patterns; in patients with dermatomyositis the pattern was similar to that of SS. The canonical discriminant analysis revealed that only 5 of 55 (9%) SS patients showed a normal capillary pattern. The abnormal capillary pattern in SS patients correlated with microvascular disturbances such as Raynaud's phenomenon, digital pitting scars and low finger temperature. Our results indicate that quantitative analysis of the nail fold capillaries is useful in evaluating the microvascular disturbances in SS patients.