Characterization of microvascular disease in patients with sickle cell disease using nailfold capillaroscopy

Sickle cell disease (SCD) is a disorder characterized by repetitive vaso-occlusive crises causing microvascular obstruction, tissue ischemia and pain that may lead to chronic multi-organ ischemic sequelae. Nailfold videocapillaroscopy (NFC) is a non-invasive imaging technique used in clinical rheumatology to directly visualize capillaries located near the fingertip. To characterize NFC abnormalities in the setting of SCD, we performed NFC on 71 SCD patients and 70 age matched controls using a video capillaroscope on 8 digits. As compared to controls, mean capillary number was lower and the final capillary score (measure of capillary dropout inversely related to capillary density) was higher in the SCD group. The SCD group had a lower percentage of stereotype hairpin shapes and a higher percentage of crossing type capillaries. On multivariate linear analyses, both mean capillary number and final capillary score were independently associated with SCD after adjusting for age, body mass index, and gender. SCD was associated with more dilated capillaries but similar numbers of hemorrhages. In conclusion, SCD is associated with lower capillary density and more dilated capillaries on NFC. These changes appear unrelated to markers of disease severity including frequency of sickle crises, number of transfusions, and HbS levels. The relation between NFC and target organ involvement merits further study.