AB0956 To what extend is nail ultrasound discriminative between psoriatic arthritis and healthy subjects?

Abstract

BackgroundClinical physical examination can detect superficial nail changes in psoriatic patients. However, the nail matrix and bed are not accessible for clinical assessment. Recently, ultrasonography (US) has emerged as a useful tool to assess nail involvement in psoriatic arthritis (PsA) patients.ObjectivesTo assess the discriminative utility of nail features detected by B-mode (BM) and color Doppler (CD) ultrasound (US) between patients with psoriatic arthritis (PsA) and healthy controls (HC).MethodsThis was a cross-sectional study including PsA patients and HC.All patients and controls underwent an US assessment of the fingernails that included the study of morphological changes based on Wortsman’s description [1]: focal hyperechoic involvement of the ventral plate without involvement of the dorsal plate (type I), loosening of the borders of the ventral plate (type II), appearance of wavy plates (type III) and loss of definition on both plates (type IV), blood flow disturbances and measurement of the thickness of nail bed (NBT), nail plate (TNP) and adjacent skin.ResultsA total of 536 nails were examined (PsA:326 nails, HC:210). Patients with PsA had significantly more morphological changes of the nails than healthy controls (23% vs 3.33%, p = 0.006).In PsA patients, the most frequently observed aspect was type III (47 nails, 14.4%), followed by type II (40 nails,12.3%) and type IV (38 nails, 11.6%). In HC, the only observed type was type (type II). US detected subclinical nail involvement in 37 healthy nails among PsA patients (11.34%). On the other hand, seven nails with clinical involvement did not demonstrate US changes: perionyxis (n=1), pitting (n=2), onycholyses (n=3), hemorrhage (n=1).The power Doppler signal of the nail bed and matrix was comparable between the groups (54% vs 61%, p= 0.603 and 41% vs 37.1%, p=0.432, respectively).NBT and skin thickness were higher in the HC group than the PsA group (1.90±0.22 mm vs 2.07±0.34 mm, p=0.047 and 2.25±0.69 vs 2.59±0.31 mm, p=0.002, respectively). While NPT was similar between the groups (0.38±0.09 vs 0.36±0.07mm, p=0.239).ConclusionUs detected morphological changes in clinically healthy fingernails in both PsA patients and healthy controls. However subclinical involvement was more common in PsA patients.Loosening of the borders of the ventral plate (type II) was the only aspect observed in HC. This would suggest that this type is not a specific feature of psoriatic nail.With regards to nail plate thickness, the measurements were similar between PsA patients and HC as previously reported by Mondal et al [2].However, unlike previous studies, we showed that the nail bed and skin thickness were significantly higher in healthy controls than PsA patients [3].