Improving the sensitivity and spesificity of skin pathergy test for diagnosis of behcet's disease

.IMPROVING THE SENSITIVITY AND SPESIFICITY OF SKIN PATHERGY TEST FOR DIAGNOSIS OF BEHCET'S DISEASE Objective: The sensitivty of skin pathergy test (SPT) has been declining over time despite the application of different techniques. We aimed to improve sensitivty and spesificity of SPT for diagnosis of Behcet's Disease (BD), and evaluation of cytokine release using a WBA-based in vitro SPT model. Method: In addition to traditonal 20G needle, 21G contact-activated lancets were used solely or with 23-valent polysaccharide pneumococcal vaccine, Alum or ATP as triggers and evaluated for the developement of erythema and induration at both 24th and 48th hours by the same observer. Study groups composed of BD patients with active disease and in remission, patients with other rheumatic diseases, inflammatory bowel disease, recurrent aphtous stomatitis, or with some findings of BD but not fulfilling the criteria, and healthy controls. Also, cytokine analysis was performed in a WBA-based in vitro model with the same triggers. Results: Combination of pneumococcal vaccine and 20G needle showed the highest sensitivity and spesificity for active BD (80.3% and 100%) and whole BD groups (64.3% and 100%). Usage of 21G lancet wth pneumococcal vaccine was the second most successful technique with 30% and 25.9% sensitivity for active and whole BD groups. Although erythema was observed in some other diseases and healthy controls at 24th hours, persistance of erythema was spesific for BD. Positivity of DPT was found to be related to the disease activity and usage of immunosuppressive drugs. With pneumococcal antigens, IL-1β and IL-1RA secretion increased in active BD group, while response to LPS was similar in all groups. 13 Conclusion: DPT with pneumococal polysaccharide antigens and 20G needle combination seems to be a candidate test for daily practise owing for its better sensitivity and spesificity scores compared to traditional DPT.