FRI0423 NAIL ULTRASONOGRAPHY FINDINGS IN GRAYSCALE AND POWER DOPPLER TO DIFFERENTIATE PSORIATIC ARTHRITIS, PSORIASIS AND CONTROL INDIVIDUALS

Background The early diagnosis of psoriatic arthritis (PsA) on patients with psoriasis (PsO) is challenging, but may prevent functional impairment. Patients with nail psoriasis have an odds ratio of nearly 3.0 of developing psoriatic arthritis. Ultrasonography is a replicable, radiation-free method that could be used to identify nail changes before clinical manifestations. Objectives To verify if nail changes identified via ultrasonography can differentiate between PsA and PsO patients as well as between PsA/PsO patients and a control group. Methods Single-center, cross-sectional study. PsA patients were consecutively enrolled, PsO and controls were matched by age and gender with the PsA group. PsO patients must have had the diagnosis of psoriasis of any subtypes. PsA patients had to fulfill the CASPAR criteria. Exclusion criteria, for all groups included: other joint inflammatory disease; dermatological or systemic disease that could modify the nail structure. Ultrasound examination was performed using a MyLab 50 system (Esaote Biomedica, Genova, Italy), equipped with a linear probe of 18 MHz in greyscale (GS) and 8.0 MHz in power doppler (PD). The exams were performed in a room with temperature between 22°C and 26°C, after a 10 minutes rest period. Patients were seated, with hands and fingers in a neutral position over the table. The nails were scanned on a longitudinal plane. The 2nd and 3rd fingernails of both hands were examined. Through GS, the following characteristics were assessed: 1) the trilaminar appearance of the nail plate (NP), that was classified according to Wortsman characterization of changes on psoriatic nails (I – IV), 2) the nail plate thickness (NPT), 3) the nail bed thickness (NBT), and 4) the nail matrix thickness (NMT). The signal of PD in the nail matrix and in the nail bed were evaluated together and classified according to Gutierrez et al.’s score (1-3). Comparisons between independent means were analyzed using ANOVA or Kruskal-Wallis test. The association between categorical variables was calculated by chi-squared test or Fisher’s exact test. Results In the trilaminar structure (TS) evaluation, 137(99.3%) of the nails from control group had no change in the TS; for PsO group, 32 of the analyzed nails presented TS alterations, as follows: 9 type I, 5 type II, 7 type III and 11 type IV. For PsA group, there were also 32 of the analyzed nails that presented TS changes; 4 type I, 15 type II, 9 type III and 4 type IV. The mean NPT± SD (mm) was higher on both PsA and PsO groups when compared to the control group: 0.73 ±0.14 and 0.72 ±0.15 vs.0.67±0.10 (p=0.001), respectively. NBT and NMT means did not differ among groups. There was also no statistical difference between groups regarding the degree of nail PD, as well as no difference in the grayscale and PD evaluated parameters between PsA/PsO nails both with or without clinical involvement. Conclusion Alterations of the trilaminar structure of the NP and the NPT show differentiation between psoriatic nails and the control group, but no differentiation between PsO and PsA nails. PD, NMT and NBT means also had no differences between groups. Studies with larger sample sizes are necessary to clarify the utility of these parameters in the evaluation of psoriatic patients. References [1] Wortsman C X, Holm EA, Jemec GB, Gniadecka M, Wulf HC. Ultrasonido de Alta Resolucion en el estudio de la una psoriatica. Rev Chil Radiol.2004;10(1). [2] Gutierrez M, Di Geso L, Salaffi F, Bertolazzi C, Tardella M, Filosa G, Filippucci E, Grassi W. Development of a preliminary US power Doppler composite score for monitoring treatment in PsA. Rheumatology. 2012Jul;51(7):1261-8. Disclosure of Interests None declared