Prediction of atopy by skin prick tests in patients with asthma and/or persistent rhinitis

Patient history gives important clues about the likelihood of atopy. However, the accuracy of assessment of atopy based on detailed allergy history is low. The objective of this survey was to determine the successful prediction rate of atopy by a questionnaire and the effect of various factors on the successful prediction.

A standard questionnaire including detailed allergy history was filled in by two experienced allergists for 169 patients having bronchial asthma and/or persistent rhinitis symptoms. Skin prick test (SPT) results were predicted based on the clinical data obtained by a questionnaire. Final diagnosis was made after SPT. Sensitivity and specificity analysis of SPT results prediction was investigated using two different cut-off values (3mm and 5mm) for positive tests, and factors associated with successful atopy prediction were analysed.

SPT was predicted to be positive in 42.6% and was positive in 36.1%. Depending on SPT results with the cut-off value 3mm, prediction sensitivity was 77%, specificity was 65.3%, positive predictive value was 65%, and negative predictive value was 86%. Successful positive atopy prediction was associated with age; true negative prediction was also associated with age and high education. With the threshold of 5mm for a positive test, sensitivity, specificity, positive and negative predicted values were 91%, 61%, 14% and 99%, respectively.

It seems that the success rate of detailed history is high for negative prediction. However, detailed history alone does not seem to be efficient for atopy prediction.