Dr de Jager and colleagues from the Netherlands have extended their existing observations about a possible link between PPI use and community-acquired pneumonia (CAP). In a prospective, cohort study of consecutive patients attending a hospital emergency department with suspected CAP, they found that PPI use increased the risk of CAP due to Streptococcus pneumoniae more than two-fold. Indeed, this was the only pathogen studied that had an increased rate of infection among PPI users. Interestingly, the authors had sub-classified the CAP pathogens of interest according to their likely route of transmission (e.g. oropharyngeal spread or airborne transmission). The observation that PPI treatment was only associated with an increased rate of CAP with the major oropharyngeal pathogen is biologically plausible in that, theoretically at least, PPI-induced hypochlorhydria could promote proliferation and subsequent translocation of swallowed oropharyngeal flora.
While the authors are to be congratulated on their prospective, cohort study design, the size of the adjusted odds ratio for PPI use and S. pneumoniae CAP was still quantitatively quite small at 2.23. As the authors discuss, there is still possible unrecognised confounding and protopathic bias.
All drugs have both benefits and risks. Although there may be some inappropriate PPI use for unapproved indications, there is also much more appropriate and clinically valuable use of PPIs in the community. This is especially so among elderly patients with co-morbidity who are also among those at most risk of CAP. Therefore, it is potentially inappropriate to suggest, as the authors do, that patients at risk of CAP be identified and have their PPI use ‘curtailed’. In many of those patients, the benefits of PPI treatment outweigh the possible risks. Prescribers should continue to prescribe appropriate doses of PPIs for those patients who have a genuine requirement for them.