Risk of pneumonia associated with use of angiotensin converting enzyme inhibitors and angiotensin receptor blockers: systematic review and meta-analysis
BMJ 2012; 345 doi: https://doi.org/10.1136/bmj.e4260 (Published 11 July 2012) Cite this as: BMJ 2012;345:e4260
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To the Editor
I have read the article by Caldeira and colleagues1 with interest especially for the racial difference in the protective effect of angiotensin-converting enzyme (ACE) inhibitors: the pneumonia protective effect was higher among Asian patients than in non-Asian. ACE inhibitors are believed to induce not only cough but also swallowing reflex2. Therefore, I am not sure if all the protective effect was brought by ACE inhibitors’ cough as the editorial issue concerned3, but this protective effect of pneumonia favorable in Asian pretty matched well about the fact that ACE inhibitors induce coughing specifically in Asian4. From this point of view, now I am also suggesting to clarify if the pneumonia protective effect was higher among women than in men.
In our previously reported prospective study1 from 60 consecutive participants (with both a previous history of pneumonia within the last 2 years and dysphagia), ACE inhibitor improved the dysphagia particularly in women (Figure). Furthermore, ACE inhibitor significantly elevated serum substance P levels in women, but not in men (Figure). All participants completed the medication for 6 months without any side-effects, including cough.
These results suggested that ACE inhibitors predominantly improved dysphagia in Asian women when compared with men. This predominant improvement was accompanied by further upregulation in serum substance P levels in women. Our previous study demonstrated that the upregulation in serum substance P was observed only in participants whose dysphagia was improved2. Futhermore, ACE inhibitors induce coughing predominantly in women than in men, as widely-accepted5. Taken together, I speculate that ACEi prevents pneumonia primarily in Asian women. These results warrant further clinical trials to clarify which population (sex and race) ACE inhibitors are truly effective.
Competing interests: No competing interests
Re: Risk of pneumonia associated with use of angiotensin converting enzyme inhibitors and angiotensin receptor blockers: systematic review and meta-analysis
The authors conclude that their meta-analysis shows an important role of ACE inhibitors, but not ARBs, in reducing the risk of pneumonia. However this is not proof that ACEIs are protective, but could simply be that those who can tolerate ACEIs are at less risk of developing pneumonia. Patients with a history of respiratory problems may also be put on an ARB for fear of making respiratory symptoms worse with an ACEI induced cough. I note that a single study also showed ARBs to reduce mortality. Although under-powered as the authors suggest, it is conceivable that by reducing pulmonary oedema, both groups of drugs could prevent clinical deterioration. We all know that bacteria grow faster when water is abundant.
Competing interests: No competing interests