Receiver operating characteristic curve analysis of cutaneous skin test reactions to predict hay fever and asthma symptoms in the Normative Aging Study

Background: We used receiver operating characteristic (ROC) curves to deter mine optimal cutoff values and to evaluate the ability of ragweed, mixed gr asses, mixed trees. and house-dust antigens to predict symptoms of hay feve r and asthma. Methods: Between 1984 and 1993, 1386 members of the Normative Aging Study c ohort had at least one examination that included evaluation of cutaneous hy persensitivity to common aeroallergens by skin prick testing. Standard ques tionnaires based on the American Thoracic Society DLD-78 questionnaire obta ined information on respiratory symptoms, illness. and smoking habits. Results: Ragweed was the best univariate predictor for both hay fever and a sthma symptoms: the area under the ROC curve for hay fever was 0.71 (95%;, Ct 0.67-0.74). for asthma, it was 0.65 (95% CI 0.55-0.75). For hay fever, d ichotomizing the average reaction to four antigens at 2 mm gave a sensitivi ty of 56% and a specificity of 83%; at 3 mm, the sensitivity was 38% and sp ecificity 92%. For asthma. dichotomizing the skin test reaction at 2 mm gav e a sensitivity ranging from 30% for reaction to mixed grasses to 56%;, for the ragweed antigen reaction. Conclusions: Although in this older population skin test reactivities did n ot predict current asthma symptoms with high sensitivity, our results suppo rt the use of cutoff values of 2 or 3 mm as commonly used in studies of hay fever symptoms.