Predictors of future exacerbations in a multi-ethnic Asian population with asthma

Exacerbations are important outcomes in asthma. Risk factors for exacerbations may differ in different populations. Although various demographic and clinical variables were examined in previous studies on exacerbation risks in asthma, important variables such as ethnicity, adherence, and medication titration were not included. This study examined independent predictors of future exacerbations in a multi-ethnic asthma population in Asia, while including the variables of ethnicity, medication adherence, and medication change in our analysis.

We recruited patients with physician-diagnosed asthma in a tertiary hospital in Singapore over a one-year period. Exacerbations requiring ≥3 days of systemic corticosteroids one year prior to study enrolment (previous exacerbations) and the year following enrolment (future exacerbations) were recorded from electronic medical records. Medication adherence was based on pharmacy refill. An increase or a decrease in the Global Initiative for Asthma treatment steps were considered to be medication up- and down-titration, respectively. A multivariate logistic regression model was constructed to determine independent predictors of future exacerbations.

The study cohort of 340 patients comprised mainly of Chinese (53.2%), Malay (32.9%), and Indian (9.7%) ethnicities. After multivariate analysis, only Indian ethnicity (OR 3.75, 95% CI 1.077-13.051, p = 0.038), Asthma Control Test score (OR 0.913, 95% CI 0.839-0.995, p = 0.037), and the number of previous exacerbations (OR 1.84, 95% CI 1.416-2.391, p < 0.001) were independent predictors of future exacerbations.

There are ethnic differences in exacerbation risk in Asian populations. Each incremental worsening of the asthma symptom control score and each additional exacerbation also increases the risk of future exacerbations.