Nailfold capillaroscopy: a blinded study of its discriminatory value in scleroderma, systemic lupus erythematosus, and rheumatoid arthritis.

The appearances of the nailfold capillaries can be used to distinguish between various connective tissue diseases. In a study of 30 patients (10 with scleroderma, nine with systemic lupus erythematosus, and 11 with rheumatoid arthritis), photographs were taken of the eight nailfolds of each patient (thumbs excluded) and then coded. Each of the photographs was later analysed by a rheumatology registrar and an attempt was made to predict the patient's diagnosis using only the appearance of the nailfold. The diagnostic specificity and sensitivity were 89% and 80%, respectively. The results indicate that nailfold capillaroscopy, performed by a relatively inexperienced observer, can accurately distinguish between patients with scleroderma and those with systemic lupus erythematosus or rheumatoid arthritis.