The role of nailfold capillaroscopy in interstitial lung diseases - can it differentiate idiopathic cases from collagen tissue disease associated interstitial lung diseases?

Abstract

Nailfold capillaroscopy (NFC) is a non-invasive diagnostic test that is mostly used for early diagnosis of collagen tissue diseases (CTDs). We aimed to evaluate whether NFC findings could be a clue for discriminating idiopathic interstitial lung diseases (ILD) from CTD associated ILDs (CTD-ILD). Additionally it was aimed to determine whether NFC could be helpful in discriminating usual interstitial pneumonia (UIP) pattern from non-specific interstitial pneumonia (NSIP) pattern. We grouped patients into three main groups: 15 CTD-ILD, 18 idiopathic ILD, and 17 patients in the control group. The CTD-ILD group was split into two subgroups: 8 patients with Sjögren's syndrome (SJS)-associated ILD and 7 with rheumatoid arthritis (RA)-associated ILD. The idiopathic-ILD group consisted of 10 idiopathic NSIP and 8 IPF patients. The control group consisted of 10 SJS and 7 RA patients without lung disease. None of the patients were on acute exacerbation at the time of examination, and none had Reynaud's phenomenon. Mean capillary density was significantly reduced only in the CTD-ILD group as compared to the control group (p= 0.006). In subgroup analysis, it was determined that RA-ILD, IPF, and SJS-ILD subgroups had more severe capillaroscopic abnormalities. Mean capillary density in patients with the UIP pattern was reduced compared to patients with the NSIP pattern and those in the control group; p values were 0.008 and < 0.001, respectively. This study is to be the first describing and comparing the nailfold capillaroscopic findings of patients with NSIP and UIP patterns. NFC findings can be helpful in discriminating UIP patterns from NSIP patterns. But to show its role in differentiating idiopathic disease, more studies with more patients are needed.