The predictive value of quantitative nailfold capillary microscopy in patients with undifferentiated connective tissue disease.

The present prospective study was undertaken to follow the natural history of patients with Raynaud's phenomenon and to document in these patients the frequency with which secondary disorders develop. Seventeen patients with primary Raynaud's phenomenon (PRP) and 43 patients with undifferentiated connective tissue disease (UCTD) were examined after 6-8 years to see whether they had developed into UCTD or systemic sclerosis (SSc), respectively. Their nailfold capillary parameters were analysed statistically to ascertain whether they would predict for the development of the diseases into UCTD or SSc. Two patients with PRP(12%) developed into UCTD, and 10 patients with UCTD (23%) into SSc. In PRP, all three parameters of the patients who developed into UCTD showed a tendency to be larger than in those who did not develop UCTD. In UCTD, the apical limb width (P < 0.02), capillary width (P < 0.01) and capillary length (P < 0.01) of the subjects who developed SSc were significantly larger than those who did not. Of the clinicolaboratory findings in patients with UCTD, the occurrence rate of abnormal apical limb width (relative risk 20. 7, P < 0.01), abnormal capillary width (relative risk 10.7, P < 0. 01), abnormal capillary length (relative risk 9.2, P < 0.02) and antinuclear antibody (relative risk 9.6, P < 0.05) showed a significant predictive value for the development of UCTD into SSc. These results indicate that quantitative nailfold capillary microscopy, as well as antinuclear antibody, will provide exact predictive information in patients with UCTD in clinical practice.