Diagnostic value of pathergy test in Behcet’s disease according to the change of incidence over the time

Abstract

Pathergy test (PT) is used for the diagnosis of Behcet's disease (BD). It is a criterion in many classification/diagnosis criteria. PT is mainly seen in BD but can be seen in other conditions too. PT has been reported with high frequency from most countries along the Silk Road. The sensitivity of pathergy phenomenon (PP) is declining over the time. The aim of this study was to look for the diagnostic value of PT in the past and at the present time. The BD registry (Rheumatology Research Center, Tehran University of Medical Sciences) has the data of 6,607 BD and 4,292 control patients. Patients and controls were divided in four groups of 1,650 BD and 1,073 controls. Sensitivity, specificity, positive and negative predictive value (PPV-NPV), positive and negative likelihood ratio (PLR-NLR), diagnostic odds ratio (DOR), and Youden's index (YI) were calculated for each group. The first and the fourth quartiles were compared. Sensitivity of PT decreased from 64.2% (first quartile) to 35.8% (fourth quartile). Specificity improved from 86.6% to 98.4%. PPV improved from 82.7% to 95.7%. NPV decreased from 82.7% to 60.5%. PLR improved from 4.8 to 22.4, while NLR deteriorated from 0.41 to 0.65. DOR improved from 11.6 to 34.3. Yuden's index worsened from 0.5 to 0.34. Although sensitivity of PP decreased, the increase of specificity is a plus value for diagnosis. As a result, PPV, PLR, and DOR improved, while NPR, NLR, and YI deteriorated. Although the pathergy test lost its sensitivity during the past 35 years, it has not lost its value as a diagnostic test, improving many of its characteristics. In a practical view, the chances of getting a positive test have decreased over the time. However, a positive test is rather the synonym of Behcet's disease, with a probability of 98.4%.

Inflammatory diseases of the aorta

“…A hint to the diagnosis can be obtained from the "pathergy test", which consists of the intradermal injection of 0.1 ml 0.9 % saline to the forearm skin and is positive if a papule or pustule emerges within 24 -48 hrs. Specifi city of the test is > 90 %, but sensitivity decreases over time, presently rated to be 30 -50 % in developed countries [39] and less in patients with vascular involvement in comparison to those without (46 vs. 56 % [38]). …”

The real-world use of different anti-tumor necrosis factor agents in a Northern European population of patients with Behçet’s disease

“…It is more commonly observed among BD populations along the Silk Route and is detected more frequently in patients with HLA-B * 51 and active disease (16)(17). Its sensitivity has declined over time yet continues to carry significant diagnostic value, especially in the highly prevalent countries (16,18). The phenomenon is, however, rarely observed within the Northern European populations (19)(20)(21).…”

The Epidemiology of Behçet’s Disease

“…However, it is rarely observed in patients from Northern Europe, USA and Australia [1,56]. Although the pathergy test lost its sensitivity during the past 35 years, it is still a valuable diagnostic test [57]. Some studies from Japan and Turkey have reported a decrease in the positive pathergy reaction in BD [56].…”