Figure 2

Diagnostic procedures. With the exception of skin prick testing – SPT, case history (paying particular attention to the presence of a past or present history of asthma and/or previous asthma symptoms or asthma medication intake), physical examination and simple spirometry were repeated at baseline (1990–91) and follow-up visits (2000). Bronchial provocation testing – BPT with inhaled methacholine were carried out in selected cases on both visits.