Use of acid-suppressive drugs and risk of pneumonia: systematic review and meta-analysis

CMAJ © 2010 Canadian Medical Association or its licensors 1 Recently, the medical literature has paid considerable attention to unrecognized adverse effects of commonly used medications and their potential public health impact. One group of medications in widespread use is acid-suppressive drugs, which represent the second leading category of medication worldwide, with sales totalling US$26.9 billion in 2005. Over the past 40 years, the development of potent acidsuppressive drugs, including proton pump inhibitors, has led to considerable improvements in the treatment of acid-related disorders of the upper gastrointestinal tract. Experts have generally viewed proton pump inhibitors as safe. However, potential complications such as gastrointestinal neoplasia, malabsorption of nutrients and increased susceptibility to infection have caused concern. Of special interest is the possibility that acid-suppressive drugs could increase susceptibility to respiratory infections because these drugs increase gastric pH, thus allowing bacterial colonization. Several previous studies have shown that treatment with acid-suppressive drugs might be associated with an increased risk of respiratory tract infections and community-acquired pneumonia in adults and children. However, the association between use of acid-suppressive drugs and risk of pneumonia has been inconsistent. Given the widespread use of proton pump inhibitors and histamine2 receptor antagonists, clarifying the potential impact of acid-suppressive therapy on the risk of pneumonia is of great importance to public health. Previous meta-analyses have focused on the role of acid-suppressive drugs in preventing stress ulcer, but none have examined pneumonia as the primary outcome. The aim of this study was to summarize the association between the use of acid-suppressive drugs and the risk of pneumonia in observational studies and randomized controlled trials.