Asthma control and hot weather-related respiratory symptoms

Abstract

<b>Background:</b> Climate changes continues to increase hot days in polar regions. <b>Objective</b> We assessed whether asthma control plays a role in experiencing hot weather-related respiratory symptoms among adults. <b>Methods:</b> We conducted a population-based cross-sectional study of 1995 adult subjects with doctor-diagnosed asthma (response rate 40%) living in Northern Finland. They answered two questionnaires, one of which inquired about occurrence of hot weather-related respiratory symptoms, including, shortness of breath, wheezing, prolonged cough, phlegm production, and chest pain. The other questionnaire included questions assessing asthma control based on the Asthma Control Test (ACT). These included: Disadvantage related to and occurrence of asthma-related symptoms, waking up earlier in the morning because of asthma symptoms, use of asthma bronchodilating medication, and self-assessment of asthma control during the past four weeks. The sum of ACT points ranged between 5 and 25. ACT was divided into quartiles with the score 24-25 as the reference category. Adjusted prevalence ratios (PR) were from Poisson regression. <b>Results:</b> The more poorly controlled was the person’s asthma, the more increased were the PRs of hot weather-related respiratory symptoms when compared to those with very well-controlled asthma. This trend was particularly clear for shortness of breath, wheezing, and prolonged cough. Among those with the poorest asthma control, the PR for shortness of breath was 4.99 (95% CI 3.73, 6.68), the PR for wheezing was 10.09 (4.67, 21.81), and the PR for prolonged cough was 6.11 (4.10, 9.13). <b>Conclusions:</b> Subjects with poor control of their asthma experience increased risk of having hot weather-related respiratory symptoms.