Inhaled corticosteroid (ICS) use did not increase the already heightened risk for pneumonia among inpatients with chronic obstructive pulmonary disease (COPD)-bronchiectasis overlap, according to study findings published in Chest.
The observational study used data from the Clinical Practice Research Datalink and Hospital Episode Statistics from the United Kingdom to determine how pneumonia risk among inpatients with COPD-bronchiectasis overlap compared in those who used ICS vs those who did not. Patients were identified from January 1, 2004, to January 1, 2019.
An incident ICS new-user cohort also was created, from which 2 nested case-controls were derived. Nested case-control 1 (n=84,316) included all cases involving COPD and matched control individuals. To evaluate the association between pneumonia and blood eosinophil counts, the investigators conducted a second analysis, nested case-control 2 (n=2527), which included only those participants with COPD-bronchiectasis overlap and a recent blood eosinophil count (BEC) in both the ICS and control groups. Each patient in the ICS group was matched for age and gender with 3 to 4 control individuals.
All ICS prescription records in the year before the index date were obtained. The primary analysis explored the association between ICS use and cases of hospitalized pneumonia and any change with bronchiectasis.
The COPD cohort included 316,663 patients (median age, 67.9 years [interquartile range, 58.9-76.5]; 52.6% male). Of those, 48.1% were using ICS at enrollment and 2.5% had bronchiectasis. A 24% increased risk of hospitalized community-acquired pneumonia (CAP) associated with concomitant bronchiectasis was observed in this cohort (adjusted hazard ratio, 1.24; 95% CI, 1.15-1.33; P <.0001).
Our main finding is that although ICS use and concomitant bronchiectasis independently increase the risk of hospitalized pneumonia, there is no further augmentation from ICS use in patients with COPD-bronchiectasis overlap.
Researchers also found that a 26% increase in the odds for hospitalized CAP was associated with ICS use (adjusted odds ratio [AOR], 1.26; 95% CI, 1.19-1.32). Recent ICS use had the strongest association, and the association was not significant by 180 days after ICS use (0-30 days: AOR, 1.27; 95% CI, 1.20-1.35; 30-90 days: AOR, 1.32; 95% CI, 1.22-1.42; 90-180 days: AOR, 1.14; 95% CI, 1.00-1.29; and 180-365 days: AOR, 1.05; 95% CI, 0.90-1.22).
In the analysis of nested case-control 1, concomitant bronchiectasis was a significant modifier of the association between ICS and hospitalized CAP (likelihood ratio test, P <.01). Among patients with COPD-bronchiectasis overlap, ICS was not significantly associated with pneumonia (AOR, 1.01; 95% CI, 0.8-1.28) vs COPD without bronchiectasis (AOR, 1.27; 95% CI, 1.20-1.34). For the negative exposure analysis, interstitial lung disease was not an effect modifier, which indicates the unlikelihood of significant residual confounding in the model (likelihood ratio test, P >.05).
A high BEC (>0.3 x 109 /L) was not associated with hospitalized CAP (AOR, 0.89; 95% CI, 0.53-1.24), although a normal eosinophil count (≤0.3 x 109 /L) was associated with hospitalized CAP (AOR, 1.56; 95% CI, 0.78-1.41).
Among several limitations, information on patients’ adherence to their ICS prescriptions was not available, and bronchiectasis may have been underdiagnosed in the participants. Also, microbiology data or data on severity of bronchiectasis, pneumonia risk factors, and alcohol use were unavailable. Furthermore, only an increase in hospitalized pneumonia was assessed.
“Our main finding is that although ICS use and concomitant bronchiectasis independently increase the risk of hospitalized pneumonia, there is no further augmentation from ICS use in patients with COPD-bronchiectasis overlap,” concluded the researchers. “Additionally, in our smaller cohort of only those with COPD-bronchiectasis overlap, we found that an elevated BEC appears to protect patients from the ICS-associated increased pneumonia risk, reflecting findings found in previous COPD cohorts.”