How effective are medicines that suppress stomach acid for the treatment of indigestion in adults with no other major disease?
Acid suppression is a possible treatment for functional dyspepsia (indigestion), which is recurring pain over the stomach, bloating, burping or the feeling of being full. Several medicines are used to treat functional dyspepsia; proton pump inhibitors (PPIs) and H2 receptor antagonists (H2RAs) reduce stomach acid, and prokinetics accelerate stomach emptying. There is no clear evidence that one medicine is more effective than another. Although these are considered safe, a few people have side effects. The most common side effects are headache, tummy (abdominal) pain, bloating, diarrhoea and feeling sick (nausea). Long-term use of PPIs has been associated with infectious diarrhoea (inflammation of the stomach and small intestine), bone fracture and bacterial overgrowth. Therefore, we need to know whether these medications are effective and safe for people with indigestion.
We searched medical databases for clinical trials in which treatment was allocated by chance (called randomized controlled trials) in adults with functional dyspepsia up to May 2017. We included results from 25 studies from 27 publications. We found two studies awaiting further details and no other ongoing studies.
We included 25 studies (with 8453 participants). There were six studies (2304 participants) comparing low-dose PPIs versus standard-dose PPIs (the dose used in clinical practice); 18 studies (6172 participants) comparing PPIs with placebo (pretend treatment); two studies (740 participants) comparing PPIs with H2RAs; five studies (1033 participants) comparing PPIs with prokinetics and two studies (407 participants) comparing PPIs plus prokinetics versus prokinetics alone.
The duration of the treatment lasted at least two weeks. Seven studies reported treatment for two weeks, 12 studies reported treatment for four weeks and five studies reported more than six weeks of treatment. The treatment period was unclear in one study.
Study funding sources
Seventeen of the 25 studies were sponsored or funded by a pharmaceutical company and two by an institution grant. There was no information on funding in eight studies.
Our review showed that PPIs are more effective than placebo, and are probably slightly more effective than prokinetics for the treatment of functional dyspepsia. Low-dose and standard-dose PPIs were similarly effective on the relief of indigestion, so we combined the results of the two doses of PPI. PPI was more effective than placebo, with 31% of the PPI group reporting no or minimal symptoms compared with 26% of the placebo group. The effect of PPI was probably slightly more effective than H2RAs; however, the two studies involved in the analysis were so different that it may have influenced the results. There was no difference in the number of reported side effects when comparing PPIs, H2RAs and prokinetics.
Quality of the evidence
The studies evaluating the effect of PPIs compared to placebo or PPIs combined with prokinetics versus prokinetics were in general of good quality. However, the studies that compared PPIs versus H2RAs and prokinetics had serious quality issues.