April 20, 2017

expert reaction to research on inhaled asthma steroids and pneumonia risk

Publishing in the British Journal of Clinical Pharmacology, researchers looked at the relationship between use of inhaled corticosteroids and pneumonia risk in COPD patients.

Prof. David Spiegelhalter, Winton Professor for the Public Understanding of Risk at the University of Cambridge, said:

“To put the main result in perspective, nearly 700 people using inhaled corticosteroids for one year was associated with one extra hospitalisation for pneumonia.  And the authors acknowledge that any real causal effect is probably even weaker.”

Prof. Patrick Wolfe, Professor of Statistics at UCL, said:

“This is an appropriately caveated study where the authors point out that their results are at odds with previously published studies.  While they conclude an increase in the relative risk of pneumonia amongst a certain population of asthma sufferers who use inhaled corticosteroids, the authors note that the absolute risk reported is small – less than 1.5 extra cases per 1000 person-years – and may be due to other factors that were not available in the data studied such as smoking, environmental exposures, etc.

“This is a study of the relationship between inhaled corticosteroids (ICS) and hospitalisation for pneumonia, which the authors note ‘disagrees with the conclusions of the only other study published that directly assessed this relationship’.

“It is important to note that the authors conclude: ‘Per 1000 person-years, the overall use of ICS was found to be associated with 1.44 extra cases of hospitalized pneumonia.’  The authors’ reported increase in relative risk is still present, but at a much reduced level of 32% (noting that 9%-60% captures the 95% confidence interval for this figure), ‘when considering the possibility that prescriptions for an ICS near a pneumonia event might actually be due to early signs of pneumonia (protopathic bias) and when restricting the comparison group to subjects with more active treatment for respiratory disease.’ The authors note that this scenario is ‘likely more representative of the true magnitude of effect of ICS on pneumonia risk in asthma patients with similar levels of severity.’

“The authors appropriately and correctly highlight a number of limitations, both concerning the population under study and noting that ‘the possibility of residual confounding arising from unmeasured factors remains a concern. For example, in this study, had the data been available, smoking and other environmental exposures would be important factors to consider.’

“The senior author of the study summarises it effectively when he states: ‘While the increase in risk of pneumonia with the use of inhaled corticosteroids is well recognized in chronic obstructive pulmonary disease (COPD), in asthma patients the evidence has been equivocal. Our study suggests the risk may be present in asthma, although pneumonia in patients with asthma remains unusual and inhaled corticosteroids remain the best therapy available.’

“It’s important to focus on the absolute numbers in this study, since the risks are so small relative to the benefits of asthma medication use.  Moreover, as the authors rightly note, there may be other factors such as smoking or environmental conditions which could account for the reported increase in risk.”

* ‘Pneumonia Risk in Asthma Patients using Inhaled Corticosteroids: A Quasi-Cohort Study’ by Christina Qian et al. published in the British Journal of Clinical Pharmacology on Thursday 20 April 2017.

Declared interests

None declared