BACKGROUND Inhaled corticosteroid (ICS) is recommended in the management of patients with asthma-chronic obstructive pulmonary disease overlap syndrome (ACOS), but its effectiveness has not been clearly proved.

OBJECTIVE To evaluate whether ICS has effects on outcomes of ACOS.

METHODS In this observational 12-year retrospective cohort study involving 125 patients with ACOS from Seoul National University Hospital, the annual rate of decrease in forced expiration volume in 1 second, the incidence rate of severe exacerbation, and overall mortality in an ICS-treated group were compared with those in a non-ICS-treated group.

RESULTS Of 125 patients with ACOS, 90 and 35 were categorized to the ICS and non-ICS treatment groups, respectively. There were no significant differences between the 2 groups in the annual rate of decrease in forced expiration volume in 1 second (9.61 mL/year in ICS treatment group vs 15.68 mL/year in non-ICS treatment group, P = .598). Compared with the non-ICS treatment group, the ICS treatment group did not show a decrease in the risk of severe exacerbation (adjusted incidence rate ratio 1.24, 95% confidence interval 0.44-3.46). Time to death also did not differ between the 2 groups. Even when analyses with propensity score matching were performed, the results were similar.

CONCLUSION In the management of ACOS, the use of ICS was not significantly associated with improvements in the annual rate of decrease in forced expiration volume in 1 second, the incidence of severe exacerbations, and overall mortality compared with the non-ICS treatment group.