Background/Purpose: Raynaud’s phenomenon (RP) is commonly seen in rheumatology practice. Differentiating primary from secondary RP is important for disease management and prognosis. How does capillaroscopy compare to color Doppler ultrasound (US) of the finger arteries for distinguishing primary from secondary RP? How often do these imaging techniques detect abnormalities in nailfold arteries or finger arteries in patients with connective tissue diseases?

Methods: Consecutive patients with RP or with suspected connective tissue disease and healthy controls who presented within a 12-month period in a tertiary rheumatology referral center were examined.

Nailfold capillaroscopy of the 2^nd to 5^th fingers was done bilaterally with a Nikon Stereoscopic Zoom Microscope SMZ1000 including a camera control unit DS-Us, in search for scleroderma, dermatomyositis and other connective tissue disease patterns as previously described (Cutolo M, et al. Best Pract Res Clin Rheumatol 2008;22:1093-108).

Bilateral color Doppler US of the radial, ulnar, all common palmar and all proper digital arteries was performed after a hot water bath of the hands in search for occlusions and stenoses as previously described (Schmidt WA, et al. J Rheumatol 2008;35:1591-8). An Esaote MyLab Twice US machine, equipped with a 6-18 MHz linear probe, was used.

Capillaroscopy and US images were stored electronically. Both investigators were not aware of the results of the other examination. After diagnostic work-up the results of US and capillaroscopy were compared with the final diagnosis.

Results: Twenty healthy controls and 165 patients were included. Final diagnoses included primary RP (52 patients), systemic sclerosis (49 patients), myositis (15 patients), other connective tissue diseases such as SLE (13 patients), MCTD (12 patients), UCTD (10 patients), Sjögren’s syndrome (4 patients) and vascular diseases such as vasculitis (5 patients), anti-phospholipid syndrome (3 patients), and arteriosclerosis (2 patients). Table 1 shows the results.

Table 1:

Diagnosis	N	Consistent   results of US and capillaroscopy	Only   US positive	Only   capillaroscopy positive	Kappa
Controls	20	100%	0%	0%	N.A.
Primary RP	52	71%	10%	19%	-0.10
Systemic   sclerosis	49	88%	8%	4%	0.81
Myositis	15	67%	7%	27%	0.68
Other   connective tissue diseases	39	80%	5%	15%	0.73
Vascular   disease	10	50%	20%	30%	0.51
Total	185	79%	7%	14%	0.58

The highest rate of abnormalities was found in systemic sclerosis (capillaroscopy, 92%;  US 96%). In myositis (87%; 67%) and other connective tissue diseases (82%; 72%) capillaroscopy more often displayed abnormal results than US. In primary RP, US and capillaroscopy were positive in 10% and 19% respectively. None of these patients showed abnormalities in both US and capillaroscopy.

Conclusion: Although capillaroscopy and US are assessing different anatomical structures, each technique helps distinguish primary from secondary RP. Abnormalities are particularly common in systemic sclerosis. Capillaroscopy is more sensitive in other connective tissue diseases. However, it is more frequently positive also in primary RP. The agreement between US and capillaroscopy is good to moderate.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/capillaroscopy-compared-with-color-doppler-ultrasound-of-digital-arteries-for-distinguishing-primary-from-secondary-raynauds-phenomenon/