Rather than doing a new study, the researchers used a technique called meta-analysis to combine information from 10 selected previous studies. For a study to be included, it must have assigned patients at random to receive either combination therapies for H. pylori or therapies that were not active against H. pylori infection. Most of the combination therapies included three drugs. Treatment lasted for 1 to 2 weeks. The researchers asked patients about dyspepsia symptoms 6 weeks to 2 years after treatment, depending on the particular study.