Validation of the Adult Asthma Epidemiological Score: a secondary analysis of EPI-ASTHMA

Abstract

Background: The A2 score is an 8-question patient-reported outcome measure that has been validated for ruling in (score ≥4) and ruling out (score 0-1) asthma. However, this screening tool has been validated in a cohort similar to the derivation cohort used. Objective: This study aims to validate the predictive accuracy of the A2 score in a primary care population against general practitioner (GP) clinical assessment and to determine whether the proposed cut-offs are the most appropriate. Methods: This accuracy study is a secondary analysis of the EPI-ASTHMA population-based study. Random adult participants recruited from primary healthcare centers in Portugal were analyzed. Participants answered the A2 score by telephone interview. Those with an A2 score ≥1 (plus 5% with an A2 score of 0) were invited to a diagnostic visit carried out by a GP to confirm or not a diagnosis of asthma. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) curves. Results: A total of 1283 participants (median 54[p25-p75 43-66] years; 60% female) were analyzed. The A2 score showed high discriminatory power in identifying asthma, with an area under the ROC curve of 82.9(95%CI 80.4-85.4)%. The proposed cut-off ≥4 was the most appropriate to rule in asthma (specificity 83.1%, positive predictive value 62.4%, accuracy 78%). Similarly, the proposed cut-off <2 was the most suitable at excluding asthma (sensitivity 92.7%, negative predictive value 93.7%, accuracy 60.5%). Conclusion: The A2 score is a useful tool to identify patients with asthma in a primary care population.