Respiratory tract infection-induced asthma exacerbations in adults with asthma: assessing predictors and outcomes.

Objective: To evaluate clinical and economic burden associated with respiratory tract infection (RTI)-induced asthma exacerbations and to identify risk factors associated with these exacerbations. Factors associated with these exacerbations are understudied and little information is available about consequent expenditures. Methods: In this retrospective case-control study, medical records and pharmacy data in King Abdullah University Hospital in Northern Jordan were reviewed for adults with asthma aged 40 years and older, over the period 2013-2016. Cases of RTI-induced asthma exacerbations were identified, and controls were selected randomly from asthmatic adults who did not experience any RTI-induced asthma exacerbation during the same period. Independent-samples t-tests and chi-square tests were conducted to compare patient characteristics of cases and controls. Predictors of RTI-induced asthma exacerbations and the resultant complications were evaluated using multivariable logistic regression. Multivariable regression on log-transformed charges was used to predict expenditures of these exacerbations. Results: A total of 137 cases and 548 controls were identified. Using inhaled corticosteroid + long-acting beta-agonists (ICS + LABA) was significantly associated with lower odds of RTI-induced asthma exacerbations (OR = 0.4; 95% CI, 0.21-0.77; p = 0.006), and lower odds of resultant serious complications (OR = 0.23; 95% CI, 0.07-0.69; p = 0.009), compared to being untreated with any asthma maintenance treatment. Asthma severity and co-morbidities were associated with increased susceptibility to these exacerbations. The average charges of RTI-induced asthma admissions and outpatient exacerbations were 1042.9 JD ($1471.0) and 81.1 JD ($114.4), respectively. Conclusions: ICS + LABA, asthma severity and co-morbidities appeared to affect the clinical and economic burden associated with RTI-induced asthma exacerbations. Efforts to prevent these exacerbations in patients with risk factors are warranted.