In: Asthma10 Jun 2014
Because there have been relatively few studies using each antireflux medication, all of the English-language, peer-reviewed, placebo-controlled studies of the effects of antireflux medication on asthma were combined for analysis. The inclusion of studies using the different antireflux regimens is justified by the similarity of their outcomes. The combined data show that the majority of patients experienced an improvement in asthma symptoms and their asthma medication requirements decreased, even though lung function did not improve (Fig 1).
There are several explanations for the apparently paradoxical findings of medical antireflux therapy producing an improvement in asthma symptoms but not in lung function. Most authors have concluded that treatment of GER has only a minor effect on asthma; ie, enough to control symptoms but not enough to affect pulmonary function. Another interpretation is that treatment of GER has an effect on some but not all asthmatics with GER Demeester et al performed ambulatory pH monitoring in patients with chronic cough and GER. Asthma inhalers this They found that GER only triggered cough in some patients with both GER and cough. An analogous situation may exist in asthmatics. A variety of triggers, including viral infection, antigen exposure, exercise, cold air, and smoke, affect some but not all asthmatics. Gastroesophageal reflux may also affect only some asthmatics. In one study, regurgitation and proximal GER correlated with a beneficial asthma response and the presence of RARS did in another. Perhaps there are features that make GER more irritative to some asthmatics and explain the variable response to therapy.
The presence of esophagitis may be necessary for GER to adversely affect asthma control. Refluxate may contain bile acids and trypsin, which can cause esophagitis despite adequate acid suppression. This may explain the apparent lack of response to acid suppression in some patients.
Another possibility is that asthma improves with antireflux therapy and allows patients to reduce their asthma medication requirements. However, the reduction in asthma medication masks the improvement in lung function.
Figure 1. Effects of medical antireflux therapy on asthma symptoms, asthma medication use, peak expiratory flow rate (PEFR), and spirometry in the eight randomized, placebo-controlled trials. Each pair of columns shows the number of patients in the studies that improved (black bar) and did not improve (gray bar).
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