Background: Many United Kingdom patients with asthma and rhinitis are allergic, but in primary care few diagnostic and management decisions are made with formal allergy assessment. Arguably, knowing a patient's atopic status might be helpful in distinguishing the cause of disease and in selecting appropriate treatments.
Objectives: Our objective was to estimate the extent to which a formal allergy assessment (a structured allergy history and skin prick tests to 5 common aeroallergens) would improve the precision of allergy diagnosis compared with a patient's self-report or the structured allergy history alone.
Methods: One hundred twenty-seven patients with asthma, rhinitis, or both were recruited from 4 general practices in Wessex, United Kingdom. Allergy status based on the patient's opinion and on structured allergy history alone was compared with formal allergy assessment. Assessments were validated by an independent allergy specialist reviewing the files. Patients were given written advice specific to their allergies and followed up 3 months later to assess satisfaction, recall, and effect on health and behavior.
Results: Self-reporting misclassified allergic status in many patients. A structured allergy history alone was little better and resulted in false-positive rates for cat allergy of 32%, grass pollen of 48%, house dust mite of 75%, tree pollen of 54%, and dog of 27% compared with formal allergy assessment. Skin prick testing combined with a structured history was essential to reach a correct causative diagnosis. Three months later, 41% patients had made changes to lifestyle, medications, or both, and 18% reported clinical improvement.
Conclusions: Skin prick testing improves the accuracy of an assessment of allergic status based on patient opinion or a structured allergy history alone.