Development and validation of a screening questionnaire for allergy airway diseases (ASF Screening Questionnaire)

Background: Aim of this study was the development of a screening questionnaire for allergic respiratory diseases. The questionnaire should be as short as possible and easy to administer. Methods: The test version consisted of 33 items asking for the occcurrence of typical symptoms and whether these symptoms were associated with specific circumstances (e.g. season, contact to animals). Additionally, the severity of symptoms was rated on a 10-point scale. The questionnaire was tested on a sample of patients from the practices of 185 dermatologists, ENT physicians, pulmonologists and pediatricians who were all specialized in allergology. Each study physician should include all subsequent patients who visited the practice for the first time during a specified period (April-July 2003). Of 13,604 documented cases 8,822 patients could be included in the analysis. Excluded patients had either incomplete data or diagnostic assessment was not finished. Allergic airway disease was confirmed by positive skin or laboratory tests in 1,562 of these patients (prevalence 17.7%). Logistic regression analyses were performed to identify the questionnaire items most predictive of a diagnosis of allergic airway disease. For these items, a simplified scoring procedure was defined leading to the calculation of the additive ASF Score (range 0-24) for each patient. To determine cut-points of the ASF Score for the diagnosis of allergic airway disease we calculated the sensitivities, specificities and predictive values for all possible values of the score and for 3 prevalences. Results: The multivariate regression model identified 12 items (Nagelkerke R-2 = 0.532). Depending on the study purposes, 2 cut-points of the ASF Score are recommended that yield positive predictive values (at prevalence 17,7%) of 50% or of 67%, respectively. Conclusion: The ASF Questionnaire is an effective screening test to identify patients with possible allergic air-way disease that is very short and easy to administer.