The Capillaroscopic Skin Ulcer Risk Index (CSURI) can be used to evaluate patients with systemic sclerosis for the risk of skin ulcerations on the fingers. It may also give insights to the severity of a microangiopathy. The authors are from University of Modena and Reggio Emilia in Italy.
Patient selection: systemic sclerosis
Method: nailfold videocapillaroscopy
The second through fifth fingers of both hands are examined, with at least one capillaroscopic nailfold image per finger.
Parameters:
(1) number of capillaries in the distal row (N)
(2) number of megacapillaries (M)
(3) maximum diameter of megacapillary in micrometers (D)
The finger image analyzed has the lowest N and highest M (sort by N and take the lowest value with at least one megacapillary; sort images with that N and choose the one with the highest M).
CSURI =
= (M value) * (diameter in micrometers) / ((N value)^2)
Interpretation:
• minimum score: 0 (when M = 0)
• The maximum score is affected by the diameter of the megacapillary.
• A cutoff of >= 2.94 was used in 2009 and >= 2.96 in 2012
Performance:
• The area under the ROC curve is 0.93 for new ulcer appearance for scores >=2.94.
• A cutoff value of 2.94 had a sensitivity of 0.94 and specificity of 86% for new skin ulcers.