According to the authors of this article, previous research from Canada suggested that inhaled corticosteroid (ICS) use could increase the risk of developing tuberculosis (TB). The incidence of TB is however very low in this population and therefore the potential impact could have been underestimated.
The purpose of the current study therefore was to evaluate the association between ICS use and development of TB in South Korea, where the incidence of TB is higher (97 cases per 100,000 population per year). It was a nested case-control study based on the Korean national claims database, which includes information on all medical services rendered (along with diagnostic codes) and all prescription medicines dispensed.
A total of 853,439 new users of respiratory medicines (ICS, muscarinic antagonists and/or beta-2 agonists) who had no documented history of TB were identified and made up the source population. Cases of TB (defined as ICD-10 diagnosis and ≥2 anti-TB medicines prescribed within 90 days) occurring after the date of initiation were then identified within this cohort and matched to up to five controls according to age, sex, diagnosis of COPD or asthma, and initiation date.
A total of 4,139 individuals with newly diagnosed TB were matched with 20,583 controls. Use of ICS (prescription for 30 days or longer identified during the one-year period prior to the index date) was associated with an increased rate of TB diagnosis (adjusted odds ratio (aOR) 1.20; 95% CI 1.08-1.34). This association was found to be dose-dependent (p for trend <0.001). Of note, oral corticosteroid use was also associated with an increased risk of TB development (aOR 1.83; 95% CI 1.58-2.12), and a subgroup analysis suggested that ICS only increased TB risk in those who were not using oral corticosteroids.
The authors discuss the limitations of their study, including the inclusion of heterogeneous patients and the lack of information on smoking status. Based on their findings, they suggest that testing for latent TB should be considered in patients who require long-term use of a high-dose ICS inhaler, and say that clinicians should be aware of the possibility of TB development in these patients.