Predictors of respiratory symptoms in a rural Canadian population: A longitudinal study of respiratory health.

backgroundPredictors of new and long-term respiratory symptoms for rural residents are not well defined.

objectiveTo identify early predictors of respiratory symptoms in a rural community population.

methodsThe study population consisted of 871 adults living in the rural community of Humboldt, Saskatchewan, who participated in two cross-sectional respiratory studies conducted in 1993 and 2003. Questionnaire information obtained at both time points included respiratory symptoms (cough, phlegm and wheeze), history of allergy, smoking, and information regarding home and farm environments. Transitional modelling, in which measurement in a longitudinal sequence is described as a function of previous outcomes, was used to predict later outcomes of cough, phlegm and wheeze. Asymptomatic individuals in 1993 were assessed to determine factors associated with the development of symptoms during the study period.

resultsThe prevalences of cough, phlegm and wheeze in 1993 were 16.1%, 18.1% and 25.5%, respectively. Change in symptoms over time was significant for cough, phlegm and wheeze. The adjusted ORs (95% CI) from separate transitional models for each respiratory outcome in 1993 that predicted the same symptom in 2003 were 6.32 (4.02 to 9.95) for cough, 14.36 (9.01 to 22.89) for phlegm and 6.40 (4.40 to 9.32) for wheeze. For asymptomatic individuals in 1993, home dampness, allergic reaction to inhaled allergens and cigarette smoking were major risk factors associated with respiratory symptoms that were reported in 2003.

conclusionThe presence of previous respiratory symptoms, allergies and environmental exposures can predict the occurrence of future respiratory symptoms in adults.