Background/Purpose: Nail fold capillaroscopy (NC) and infrared thermography (IRT) allow objective assessment of digital microvascular abnormalities in patients with Raynaud’s phenomenon (RP) and have an important role in disease classification, particularly in systemic sclerosis (SSc). The relationship between NC appearances and assessment of digital microvascular function with IRT in an unselected population of patients with RP symptoms has not previously been explored. 

Methods: A retrospective review of all patients investigated with both NC and IRT for symptoms of RP between August 2010 and November 2012 was undertaken. Thermographic assessment of the resting longitudinal thermal gradient of all fingers was undertaken by calculating the mean distal dorsal difference (DDD) at 23^oC (without prior knowledge of the clinical diagnosis or NC findings). NC images were reviewed (BV and MS) and categorized as normal, non-specific abnormalities and SSc-pattern abnormalities (Cutolo, Clin Exp Rheumatol. 2007). Indeterminate cases were reviewed by a 3^rd assessor (JP) and consensus reached. A subsequent case note review was undertaken to categorize patients according to the following diagnoses; primary RP (no clinical features of connective tissue disease and ANA negative), SSc (sclerodactyly in conjunction with a SSc-specific autoantibody), fibromyalgia (FMS) (1990 criteria) and other diagnoses.

Results: One hundred and forty one patients were identified. NC appearances, IRT analysis and diagnoses are summarized in the accompanying table. NC abnormalities were associated with a significantly lower median thermographic DDD indicating more severe peripheral microvascular function (p=0.017). There was no difference between thermographic findings of patients with non-specific and SSc-pattern NC abnormalities (possibly due to small patient numbers with SSc-pattern abnormalities). NC abnormalities were present in all patients with SSc and the majority (54.5%) had SSc-pattern changes. Patients with primary RP were significantly less likely to have NC abnormalities compared with SSc (p<0.0001). Non-specific NC abnormalities were identified in 15/46 (32.6) patients with primary RP but SSc-pattern abnormalities were not identified in any patients with primary RP. NC appearances were generally normal in FMS with only a small proportion of patients (3/18, 16.7%) exhibiting non-specific NC abnormalities.

	Normal NC appearance (n=83)	Nonspecific NC changes (n=48)	SSc-pattern NC changes (n=10)
Median average DDD across all fingers, oC, median (IQR) p value vs. normal NC appearance (Mann Whitney U)	+0.15 (4.16)	-1.98 (4.21) 0.017	-2.09 (3.71) 0.099
Proportion of patients with a mean DDD < -1, n (%)	35 (42.2)	25 (52.1)	7 (70)
Clinical diagnosis, n –        Primary RP –        SSc –        FMS –        Other rheumatic Diseases	31 0 15 37	15 5 3 25	0 6 0 4

Conclusion: The presence of NC abnormalities is associated with thermographic evidence of more profound digital microvascular dysfunction in patients under investigation for symptoms of RP. The presence of NC abnormalities differs between primary RP and SSc. Despite a high reported prevalence of RP symptoms in FMS, the majority of patients have normal NC and thermographic findings.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-between-nail-fold-capillaroscopy-abnormalities-and-thermographic-assessment-of-peripheral-microvascular-dysfunction-in-an-unselected-cohort-of-patients-under-investigation-for-symptoms-of/