Control of intragastric pH and its relationship to gastroesophageal reflux disease outcomes
Proton Pump Inhibitors
Pharmacologic treatment of gastroesophageal reflux disease (GERD) is accomplished almost exclusively with medications whose primary mechanism of action is to inhibit or neutralize gastric acidity, thus treating the disease by reducing exposure to the primary injurious agent and not by decreasing actual reflux. Although clinical trials assess healing of erosive esophagitis, improvement of GERD symptoms, and quality of life (the ultimate measures of therapeutic success), pharmacodynamic studies that measure gastric acid control have been used as 1 method of assessment of the potential clinical efficacy of acid suppressant medications. Continuous intragastric pH monitoring has been used extensively to evaluate therapeutic dosing for proton pump inhibitors and comparatively characterize their antisecretory efficacy. However, the link between observed changes in gastric pH and GERD outcomes is not well established. This review summarizes and critically evaluates available evidence linking intragastric pH and GERD outcomes. A search of the published literature for relevant studies, combined with the authors' knowledge of the field, revealed few studies that directly evaluated the correlation between intragastric pH and clinical outcomes. Despite the clinical relevance of heartburn and related symptoms as an outcome for GERD patients, most intragastric pH studies that did assess outcomes were limited in their evaluation of these symptoms because healing of erosions rather than symptom relief was specified as the primary endpoint. Well-designed, long-term outcome studies are still needed to elucidate the link among GERD symptoms, acid suppressive therapy, and 24-hour gastric pH profiles.