In: Asthma14 Jun 2014
The study groups were relatively small in most of the reports. Only four studies had more than 20 subjects who completed the protocol (Table 1). This raises concerns that a beta error may have masked a beneficial effect of medical antireflux therapy. The average change in FEV1 in these studies was less than 5%, with an SD of approxi mately 30%. The required sample size, with an alpha of 0.05 and power of 0.80, would have required treating hundreds of patients. In the largest study, by Ekstrom and coworkers, only 48 patients were treated.
The presence of GER was not confirmed with objective testing in some studies. Relying on symptoms alone may lead to the inclusion of patients without abnormal GER, who would not be expected to respond to antireflux therapy. In Ekstrom et aFs study, only two thirds of the patients with GER symptoms had abnormal GER by ambulatory pH monitoring criteria. Inclusion of patients without GER may have masked or diluted the apparently beneficial response to therapy.
Some of the apparent lack of effect may be due to inadequate antireflux therapy. Canadian neighborhood pharmacy More info In some studies, neither subjective nor objective improvements in GER were documented. Reflux symptoms did not improve in two short-duration studies. The lack of improvement in asthma symptoms may have been due to inadequate antireflux therapy. The study by Harding and coworkers was the only one that confirmed that the patients were on an antireflux regimen that was sufficient to suppress GER.
Despite the considerable literature dedicated to asthma and GER throughout the past 35 years, the nature of the relationship remains controversial. Clearly, there is a strong association between the two conditions. Regular symptomatic GER is four to five times more common in patients with asthma than in other patient groups. Abnormal GER, hiatal hernia, and esophagitis are also prevalent in asthma patients. Moreover, many asthmatics experience RARS and use their β-agonist inhalers during symptomatic GER.
At first glance, the results of the medical antireflux therapy studies appear to be conflicting. Review of the data from the placebo-controlled trials indicates that treatment improves asthma symptoms and likely decreases the need for asthma medication. Paradoxically, however, lung function does not improve in the majority of patients. The challenge for future investigators will be to explain the paradox of the strong association between GER and asthma and between improvement in asthma symptoms with antireflux therapy and the absence of demonstrable changes in lung function. Which asthmatics will benefit from antireflux therapy remains to be determined.
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