POS1361 EVALUATION OF PATIENTS WITH (SUSPECTED) BEHÇET SYNDROME; DIAGNOSTIC VALUE OF PATHERGY TESTING AND OPHTHALMOLOGIC EXAMINATION

Abstract

Background:Behçet syndrome (BS) is a multisystem vasculitis of unknown etiology. A positive pathergy test (PT) is part of the ISG criteria for the classification of BS [1]. The added value of PT in the diagnostic workup is unknown. Also, it is unknown whether real time assessment of the pathergy reaction after 48 hours by a physician can be replaced by patient assessment.The diagnostic value of routine eye examination in patients with suspected BS is unclear.Objectives:Assess the diagnostic value of PT and ophthalmologic examination in (suspected) BS patients. Examine the correlation between physician and patient assessment of PT results.Methods:This prospective cohort study in (suspected) BS patients was conducted from 2009 to 2020.At baseline, patients were classified as “true” (≥3 criteria), “probable” (2 criteria) or “no” (0-1 criteria) BS according to ISG criteria and were referred to a dermatologist and/or ophthalmologist for PT and/or eye examination. The percentage of positive PT and eye examination in each group was assessed and the percentage of patients with a changed classification (probable to true BS) was determined.PT results were scored by both patients and physicians.Results:Baseline characteristics are reported in Table 1. Figure 1 displays the flowchart of diagnostic value of PT.Figure 1.Flowchart of the results of PT in (suspected) BS patientsIn 22 patients with two ISG criteria, grade I uveitis was diagnosed in 1 patient (4.5%, 95% CI [0.8,21.8]) and retinal vasculitis in 1 patient (4.5%, 95% CI [0.8,21.8]). He had shortly experienced photophobia 3 months earlier. Both patients (9%, 95% CI [2.5,27.8]) changed from “probable” to “true” BS, the latter also had a positive PT.47 patients assessed the results of their own PT. The dermatologist scored PT as positive in one patient. This patient scored the results as unsure on all six PT points. In 46 patients, the dermatologist scored PT as negative, a total of 26 patients (56.5%, 95% CI [42.2,69.7]) scored their results negative as well.Conclusion:The added diagnostic value of PT in patients fulfilling 2 features of the ISG criteria was limited in our study, i.e. 5.7% 95% CI [1.6,18.6]. Furthermore, half of patients scored their true negative PT result as negative. The added diagnostic value of routine eye examination in probable BS patients was limited in our study.