CURRENT ALLERGIC-ASTHMA AND RHINITIS - DIAGNOSTIC EFFICIENCY OF 3 COMMONLY USED ATOPIC MARKERS (IGE, SKIN PRICK TESTS, AND PHADIATOP(R)) - RESULTS FROM 8329 RANDOMIZED ADULTS FROM THE SAPALDIA STUDY

Total serum IgE, Phadiatop(R), and the skin prick test (SPT) are commo nly used to diagnose atopic diseases. However, no large study has ever been done to test their diagnostic efficiency. We studied the diagnos tic value of these three atopic markers in 8329 well-randomized adults from the Swiss Population Registry. The prevalence of current allergi c asthma (CAA) was 1.8% and of current allergic rhinitis (CAR) 16.3%. The prevalences of positive Phadiatop, positive SPT (at least, one out of eight SPT to common aeroallergens with a wheal of 13 mm), and posi tive total IgE (IgE greater than or equal to 100 kU/1) were 29, 23, an d 23%, respectively. To diagnose CAA and CAR, the sensitivity of Phadi atop was significantly higher than that of SPT (72.5% vs 65.4%, 77.1% vs 68.4% respectively; P<0.01 and <0.001) and IgE (72.5% vs 56.9%, 77. 1% vs 43.9%, respectively; both P<0.001). The sensitivity of SPT was s ignificantly higher (68.4% vs 43.9% P<0.001) than that of IgE to diagn ose CAR. When CAA and CAR were excluded, the SPT specificity was signi ficantly higher than that of Phadiatop (77.8% vs 71.9% and 85.9% vs 80 .5%, respectively; both P<0.001): when CAR was excluded, SPT was signi ficantly higher than IgE (85.9 vs 81.4%; P<0.001). SPT had significant ly the best positive predictive value for CAA (5.2% for SPT vs 4.6% fo r both IgE and Phadiatop; both P<0.001) and CAR (48.7% for SPT vs 43.5 % for Phadiatop and 31.6% for IgE; both P<0.001). The three markers of atopy had roughly the same negative predictive value (NPV) for CAA, b ut IgE had a significantly lower NPV for CAR than SPT and Phadiatop (8 8.1% vs 93.3% and 94.7%, respectively; both P<0.001). The diagnostic e fficiency of SPT was significantly higher than that of Phadiatop (83.1 % vs 79.9% and 77.6 vs 71.9%, respectively; both P<0.001) to diagnose CAR and CAA. IgE and SPT had equal efficiency (77.6%), which was signi ficantly higher than that of Phadiatop, to diagnose CAA (71.9%; both P <0.001). In conclusion, SPT have the best positive predictive value an d the best efficiency to diagnose respiratory atopic diseases. Further more, SPT give information on sensitivity to individual allergens and should therefore be used primarily by clinicians to assess respiratory allergic diseases. Moreover, they are cheaper and provide immediate, educational information for both patient and physician.