Inhaled Steroids May Increase Risk for Lung Infection

Lara C. Pullen, PhD

September 20, 2018

Use of inhaled corticosteroids (ICS) may increase the risk for nontuberculosis mycobacterial (NTM) pulmonary infection, according to a study published online September 14 in the Annals of the American Thoracic Society.

"The magnitude of the effect revealed in this analysis and the very substantial clinical consequences of NTM pulmonary infection raise the important question of whether the broad and increasing use of ICS for [chronic obstructive pulmonary disease] needs to be reconsidered," write Vincent X. Liu, MD, a research scientist at Kaiser Permanente in Oakland, California, and colleagues.

The prevalence of NTM pulmonary infection, which is caused by an environmental organism, is increasing. Although the reasons for the rise remain unclear, recent studies have suggested that ICS use may be a factor.

To further investigate the possibility, Liu and colleagues performed a case-control study among patients treated for chronic airway disease, including asthma, chronic obstructive pulmonary disease, and bronchiectasis, between 2000 and 2010 in the Kaiser Permanente Northern California health system.

Overall, the team identified 549 patients with NTM pulmonary infection, as diagnosed by sputum cultures, for an estimated rate of 16.4 cases per 10,000 airway disease-treated subjects.

The team then compared use of ICS, use of other airways disease medications, and healthcare use among 248 patients with NTM infections with those of a matched cohort of patients drawn randomly from the chronic airway disease cohort.

In an adjusted analysis, any ICS use in the prior year was tied with a nearly threefold increased risk for NTM infection (odd ratio [OR], 2.80; 95% confidence interval [CI], 1.79 - 4.37; P < .01), and ICS use within the last 120 days was associated with a 2.51-fold increased risk (95% CI, 1.40 - 4.49; P < .01).

Moreover, duration of ICS use appeared to be a factor. "Each month of high-dose ICS use was independently associated with greatly increased odds of developing NTM pulmonary infection, even after adjusting for other airway disease treatments and healthcare utilization metrics," Liu and colleagues write.

"Our analysis of a large patient population reveals a significant association between ICS use in patients with chronic airways diseases and an increased risk of NTM infection, and complements and extends" the results of two other recent studies, they conclude. They note that all three studies showed evidence of a dose-response relationship.

Thus, although researchers remain uncertain as to the exact cause of this increased prevalence of NTM infection, ICS therapy appears to be contributing to NTM disease pathogenesis. This may be because corticosteroids alter immune function, thereby impairing the critically important host defense against pathogens.

Liu and colleagues note several limitations of their study, including significant baseline differences between the case and matched control groups, in terms of medications and healthcare utilization, and despite adjustments, there may be residual confounding.

The authors have disclosed no relevant financial relationships.

Ann Am Thorac Soc. Published online September 14, 2018. Abstract

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