INTRODUCTIONThe presence of trigger factors may help to distinguish asthma from chronic obstructive pulmonary disease (COPD). Knowing and avoiding trigger factors for both asthma and COPD can facilitate the design of comprehensive management programmes that can aid disease control. This study aimed to describe the relative frequency and range of various trigger factors in asthma and COPD.

METHODSWe conducted a telephone-based survey involving asthma and COPD patients on follow-up at a university hospital in Singapore.

RESULTSA total of 779 asthma patients and 129 COPD patients participated in this study. Among these patients, 93.8% of those with asthma and 42.6% of those with COPD had trigger factors (p < 0.001). The median number of trigger factors was greater among asthma patients than among those with COPD (3 vs. 0, p < 0.001). Trigger factors found to be significantly more prevalent among asthma patients compared to those with COPD include tobacco smoke, alcohol, upper respiratory tract infections, incense smoke, perfume, laughter, a dusty environment, air-conditioning, heavy rain, heavy traffic fumes, citrus fruits, gastro-oesophageal reflux, household pets, flowers/pollen, medications and psychological triggers. Trigger factors that were not previously described, such as bathing, fatigue, insufficient sleep, crowded places and overeating, were also reported.

CONCLUSIONTrigger factors, although found in both groups of patients, were more common among asthma patients. Knowledge of these trigger factors may be useful in distinguishing between the two diseases and optimising disease management.