A case-control study of the role of cold symptoms and other historical triggering factors in XXXX exacerbations.

@entity1 @entity565 @entity230 @entity1729
BACKGROUND: Asthma exacerbations can be provoked by many triggers such as allergens, @entity1729 . The relative importance of these has not been prospectively documented in a case-control study. OBJECTIVE: To assess the relative importance of colds and other nonclimatic historical triggers of @entity565 exacerbations. METHODS: One hundred and nineteen adults and @entity1 with @entity565 in two Canadian cities participated in a one-year study of the role of exacerbating factors in @entity565 . Among these, 36 pairs (21 adult, 15 @entity1 ) completed the case-control study. @entity1 were considered cases if they developed an acute @entity565 exacerbation and notified the centre within 24 h to allow the completion of a questionnaire and viral studies (cultures of nasopharyngeal swabs and serology). Control @entity1 with @entity565 were matched for sex, age and area of residence, had no exacerbation during the preceding four weeks and participated within 48 h of the case @entity1 . RESULTS: Case @entity1 versus control @entity1 had a mean age of 22 years versus 20 years, 50% versus 55% were male, and 92% versus 86% had at least one positive aeroallergen skin test. Cases were more likely to have taken regular inhaled @entity230 (63% versus 33%, P<0.002). Cases were more likely to report the following within the previous week: fever (P<0.001), sore throat (P<0.001), increase in nasal symptoms (P<0.01), increased dust exposure (P<0. 05), exposure to others with a cold (P<0.001) and, over the previous year, increased passive smoke exposure (P<0.05). Viral cultures and paired serology were negative. CONCLUSIONS: Symptomatic colds were the most common trigger of @entity565 exacerbations in the winter and spring, while a transient increase in dust exposure was also identified as a significant trigger. The association with chronic, passive smoke exposure and the use of inhaled costicosteroid medications likely reflected less stable pre-study @entity565 in those with exacerbations.
