Relationship between incidence and mortality of asthma with PM2.5, ozone, and household air pollution from 1990 to 2106 in the world: An ecological study

Background Asthma is a chronic airway disease characterized by an overreaction of the airways to a wide range of stimuli. Objective To determine the relationship between the incidence and mortality rate of asthma and the levels of PM2.5, ozone, and household air pollution (HAP) from 1990 to 2016 in the world. Materials and methods This ecological study was conducted across 194 countries. The asthma incidence and mortality rates were extracted from IHME Global Burden of Disease databases. Data on average annual population-weighted HAP, PM2.5, and ozone were obtained from the State of Global Air website. A model-based clustering with a finite mixture of matrix-variate normal distributions was used to identify countries with a similar pattern of three air pollution index values. The number of clusters was determined by the Bayesian information criterion, and R software was used for integrated completed likelihood criterion. The random-effects model was applied to evaluate the relationship between asthma incidence in groups and different years by using the SAS software. Results The countries were classified into five clusters in terms of the mean of PM2.5, ozone, and HAP. The incidence rates had a decreasing trend during 1990–2005 and an increasing trend during 2011–2016 in the clusters. The lowest incidence and mortality rates were observed for countries of cluster 3. The highest incidence and mortality rates were observed for countries in clusters 1 and 2, respectively. The incidence and mortality ratio trends experienced an increase in cluster 1 and a decrease in other clusters. Conclusions Depending on the mortality and incidence trends of asthma in countries in each cluster, effective national and international intervention measures are recommended to deal with such pollutants.