Insight from convergent validity of assessment of systemic sclerosis–associated Raynaud phenomenon with nailfold capillaroscopy

TL;DR

This study shows that a questionnaire for Raynaud phenomenon in systemic sclerosis correlates with nailfold capillaroscopy findings, supporting its validity.

Contribution

The study provides new evidence for the construct validity of the ASRAP questionnaire in systemic sclerosis patients.

Findings

Female patients reported higher ASRAP scores compared to males.

Nailfold capillaroscopy abnormalities like dilated capillaries and capillary dropout correlated with higher ASRAP scores.

The correlation between ASRAP and NFC was stronger in winter months.

Abstract

The assessment of systemic sclerosis–associated Raynaud phenomenon (ASRAP) questionnaire was recently developed. We tested the convergent validity of the ASRAP instrument with patient demographics and capillary morphology on nailfold capillaroscopy (NFC).

Participants completed the ASRAP (range 20–80; higher scores unfavourable) and underwent NFC using Dinolite™. We collected demographic and relevant clinical data. Two blinded assessors classified NFC images as ‘scleroderma pattern’ present or absent and recorded specific abnormalities. We assigned the NFC semi-quantitative score (range 0–3) based on the frequency of these abnormalities. Descriptive statistics were generated, and regression and correlation analyses were used to evaluate associations between ASRAP, NFC and clinical factors.

Seventy-five patients [87% women, 78% white, 77% with limited cutaneous SSc] with a mean (SD) age of 58 (14) were recruited from scleroderma clinics. ASRAP scores were 11.2 points higher in women compared with men with other significant variables held constant. The NFC semi-quantitative score weakly correlated with ASRAP (Spearman’s σ = 0.23, P = 0.05), with moderate correlation in winter (Spearman’s σ = 0.36, P = 0.04). Holding other variables constant, patients with dilated capillaries and capillary dropout had higher ASRAP scores by 6.1 and 6.8 points, respectively.

In SSc patients, females reported higher ASRAP scores. Greater proportion of ‘scleroderma pattern’ NFC abnormalities as well as specific abnormalities like dilated capillaries and capillary dropout were associated with higher ASRAP providing mechanistic insight and supporting the construct validity of ASRAP for assessing SSc-RP.

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