Background Nail disease is a common feature of psoriasis and psoriatic arthritis (PsA) and can impact quality of life significantly. The assessment of nail disease, unlike skin disease, is challenging with no tissue biomarkers feasible. Commonly used clinical outcomes include the Nail Psoriasis Severity Index (NAPSI) or the modified NAPSI system which are subjective. Optical Coherence Tomography (OCT) can detect changes in psoriatic nails and is a potential tool to assess response to therapy (1).

Objectives To evaluate OCT imaging changes in cases with nail psoriasis following 6 month-therapy with Apremilast, a PDE4 inhibitor with known efficacy for nail disease in psoriasis and PsA.

Methods Forty fingernails from four psoriatic patients were imaged at baseline and after 6 month-treatment with Apremilast 30 mg bd using Vivosight OCT scanner (Michelson Diagnostics Ltd., Kent, UK). Three OCT scans were collected from each fingernail (1 transverse and 2 longitudinal – proximal and distal) totalling 240 scans available for analysis. OCT scoring of the forty fingernails, at baseline and six months later, was carried out for changes including: 1. leukonychia/white spots; 2. pitting/localized surface irregularities; 3. diffuse surface waving; 4. onycholysis; 5. subungual hyperkeratosis. OCT score was arbitrarily calculated based on the absence (=0) or presence (=1) of each feature on the three scans of the corresponding fingernail (range 0–15). Macroscopic nail features were scored at baseline and 6 months later using the NAPSI scoring system by a Dermatologist blinded to OCT findings and compared with OCT score. Data were expressed as median (range). Comparison between baseline and follow up measurements was performed using Wilcoxon matched-pairs signed rank test. Difference between two groups and correlation were calculated using Mann-Whitney test and Spearman's test respectively. Statistical analysis was carried out using GraphPad Prism software V.7.0.

Results Based on NAPSI, twenty-eight/40 fingernails (70%) improved or remained stable after 6 months with the median NAPSI per nail falling from 3.5 (0–7) to 0 (0–6) (p<0.0001). The OCT evaluation showed that the entire gamut of nail changes exhibited improvement or stabilization in thirty-three/40 (82.5%) nails after 6 months with median OCT score per nail falling from 8 (3–14) to 4 (1–9) (p<0.0001). Difference of the change (Δ) of OCT score between baseline and follow-up significantly correlated with Δ-NAPSI (r=0.71, p<0.0001).

Conclusions OCT is able to identify all common psoriasis related nail pathology and changes after treatment. Further studies with larger numbers are needed to validate its potential role as a biomarker for nail disease.

References

1. Aydin SZ et al. Dermatology 2013.

References

Disclosure of Interest None declared