Pneumonia risk in asthma patients using inhaled corticosteroids: a quasi-cohort study

Studies have linked the use of inhaled corticosteroids (ICSs) to excess pneumonia risk in chronic obstructive pulmonary disease patients. The risk in asthma patients remains unclear. The objective of the present study was to examine the risk of pneumonia with ICSs in asthma patients aged 12-35 years.

We formed a cohort of asthma patients treated from 1990 to 2007 using Quebec health insurance databases. Subjects were considered currently exposed if they had had an ICS dispensed within the 60 days prior to their pneumonia index event or matched person-moment. Secondary analyses investigated the risk of pneumonia according to ICS dose and type. Rate ratios (RRs) and rate differences (RDs) were both estimated through a quasi-cohort approach.

The cohort included 152 412 subjects, of whom 1928 had a pneumonia event during follow-up. There was an increased risk of pneumonia associated with current use of ICSs [RR 1.83; 95% confidence interval (CI) 1.57, 2.14] or an excess risk of 1.44 cases per 1000 person-years (RD 1.44; 95% CI 1.03, 1.85). There was an excess pneumonia risk with low doses (RR 1.60; 95% CI 1.06, 2.45), moderate doses (RR 1.53; 95% CI 1.12, 2.08) and high doses (RR 1.96; 95% CI 1.64, 2.34) of ICSs, and with budesonide (RR 2.67; 95% CI 2.05, 3.49) and fluticasone (RR 1.93; 95% CI 1.58, 2.36), specifically relative to no use. When accounting for potential protopathic bias, the risk with current use of ICSs was attenuated (RR 1.48; 95% CI 1.22, 1.78).

ICS use in asthma patients appears to be associated with an increased risk of pneumonia and is present for both budesonide and fluticasone.