AB1345 PREDICTIVE MODEL FOR THE DIAGNOSIS OF PSORIATIC ARTHRITIS IN DERMATOLOGY REFERRALS ACCORDING TO PURE-4 SCALE

Abstract

BackgroundThe rate of psoriatic arthritis progression is increased in those patients presenting with established disease greater than 2 years duration, so it is necessary to find tools that allow early diagnosis to prevent joint damage1. Prevalence of psoriatic arthritis varies according to the screening strategies used. The COMPAQ study compared four screening questionnaires for psoriatic arthritis (PEST, ToPAS, PASE and EARP), whose sensitivities ranged from 44 to 91%, with the EARP questionnaire showing the highest sensitivity2. A new, shorter questionnaire, PURE-4 scale, has been developed, with a sensitivity of 85.7%3.ObjectivesTo evaluate the usefulness of PURE-4 scale in real clinical practice conditions to identify patients with psoriatic arthritis in patients with psoriasis referred from a dermatology department to a rheumatology department.MethodsRetrospective descriptive study of patients diagnosed with psoriasis who have been referred from the Dermatology Department in the last 12 months for suspected joint domain according to PURE-4 scale used by this department. The following variables were collected: age, sex, obesity, dyslipidaemia, smoking, family history of psoriasis, form of psoriasis (plaque, palmoplantar, scalp, nail), previous treatment (topical, methotrexate, other, none), PASI index, compliance with CASPAR criteria, rheumatological diagnosis (psoriatic arthritis yes/no), PURE-4 score, morning stiffness in hands, Achilles enthesitis, inflammatory low back pain and need for anti-inflammatory drugs for joint pain in the last 3 months. Descriptive statistics was performed and Chi-square test was used to compare the diagnosis of psoriatic arthritis with PURE-4 values (at the response threshold ≥ 1 it has a sensitivity of 85.7% and a specificity of 83.6%).ResultsIn the last 12 months the Dermatology Department of our hospital made 33 referrals for suspected psoriatic arthritis in patients diagnosed with psoriasis. Mean age was 46.4 ± 12.4 years, 51.5 % were men. Fifty-one percent of the patients had a BMI ≥25, 30.3% had dyslipidaemia and 45.5% were smokers; 10% of the patients had family history of psoriasis. The most prevalent form of psoriasis was plaque (18%) followed by nail (6%), palmoplantar (3%), scalp (3%) and droplet (3%) involvement; 51.5% of patients were on topical treatment, 9% on methotrexate and 39.4% on biologic treatments; mean PASI was 6.2 ± 7.5. Seventy-five percent of the referred patients did not meet CASPAR criteria; 33.3% were diagnosed with psoriatic arthritis by the rheumatologist. Of the 33 patients, 4 (12.1%) scored 0 points on PURE-4 scale; 21 (63.6%) scored 1 point; and 8 (24.3%) scored 2 points. Once assessed by a rheumatologist, 75.5% had no morning stiffness in the hands, 93.9% had no Achilles enthesitis and 87.9% had no inflammatory low back pain; only 24.2% of patients had required NSAIDs in the previous 3 months for joint pain. Finally, the diagnosis of psoriatic arthritis was analyzed against the PURE-4 cut-off point (Table 1).Table 1.Psoriatic arthritis diagnosis based on total score on PURE-4 scalePURE-4 ScoreChi-squared testp value≧ 10.250.61= 10.100.74= 20.690.41ConclusionPURE-4 scale with a score ≥ 1 does not seem to improve the diagnosis of arthritis in psoriatic patients. It would be necessary to implement other questionnaires that are more complete, but at the same time affordable, when carried out during the dermatology consultation in order to increase the sensitivity to refer or not to the rheumatologist.