The natural course of atopy determined by skin prick tests in patients with bronchial asthma and/or rhinitis.

BACKGROUND The skin prick test (SPT) is the cheapest, most widely used and practical method for the diagnosis of allergic diseases. The results of repeat test might show variations due to aging. OBJECTIVE To perform repeat SPTs to determine possible changes in the atopy rate in general as well as changes in the allergen spectrum of atopic patients occurring over time and to identify the factors that could affect this change. METHODS A total of 222 patients who received a diagnosis of bronchial asthma and/or persistent rhinitis in our Adult Allergy Unit and who attended follow-up visits in the outpatient unit over a 2-year period were enrolled. SPT with 10 visit common aeroallergens were performed at the first and the second test was performed after an interval of at least 2 years. RESULTS The mean age was 36.4 +/- 11.4 years and 77.5 % of the patients were women. The mean interval between the two tests was 43.4 +/- 20.0 (minimum = 24-maximum = 105) months. Repeat tests showed that the atopy rate decreased from 58.6 % to 47.7 %; sensitivity rates to 10 allergens also decreased. These differences were statistically significant (p <0.05). CONCLUSION The atopy rate determined by SPTs tends to decrease over time. The most important factor affecting this decrease is time itself.