The relationship of gastroesophageal reflux (GER) disease to asthma is controversial. Recent studies have suggested that reflux to the proximal esophagus may provoke asthma. The prevalence of proximal reflux in children has not been established. Diagnostically, it is not clear what the sensitivity and specificity of noninvasive techniques such as barium swallow and scintiscan are compared with the “gold standard,” pH probe, in this population. Furthermore, there is limited information on the effectiveness of combined therapy with H2 blockers and prokinetic agents in controlling reflux in children. The purpose of this study was threefold: 1) to determine the prevalence of proximal and distal GER in asthmatic children, 2) to determine the value of barium swallow and scintiscan relative to the pH probe in diagnosing GER, and 3) to determine the effectiveness of standard antireflux medical therapy in children.
Seventy-nine children and adolescents ages 2 to 17 years with “difficult to control” severe asthma requiring residential care were evaluated. None of these patients had symptoms of GER. Asthma medication included the usual inhaled antiinflammatory and bronchodilator medication, in addition to methylxanthines and oral steroids in some cases.
A 24-hour 2-channel pH probe evaluation was carried out on all patients and the prevalence of proximal and distal GER established. In addition, 63 patients had barium swallow and 62 scintiscan with Technetium 99. Using the pH probe data as the “gold standard,” sensitivity, specificity, and positive and negative predictive values were calculated. Finally, in 11 subjects a follow-up pH probe was performed after 3 weeks of antireflux therapy with ranitidine and metoclopromide.
Reflux into the distal esophagus occurred in 73% (58/79) and reflux into the proximal esophagus occurred in 64.5% (51/79) of the patients. Compared with the pH probe, the barium swallow and scintiscan faired poorly with sensitivity of 46% and 15%, specificity 82% and 73%, positive predictive value of 82% and 50%, and negative predictive values of 51% and 32%, respectively. Of 11 subjects studied by repeat pH probe, 10 had persistent GER.
Abnormal reflux into the proximal esophagus occurs in the majority of “difficult to control” asthmatic children. Barium swallow and scintiscan compared poorly with the pH probe in diagnosing reflux, particularly when they are negative. Treatment of gastroesophageal reflux with an H2 blocker and prokinetic agents had a high failure rate in this population.
This study is important because it suggests that GER, particularly into the proximal esophagus, may be an important contributor to asthma. To make that diagnosis, one needs a pH study. It is interesting to note that none of the 73% of pH positive patients had signs and symptoms of GER. However, the data are somewhat suspect because one doesn't know precisely what the severity of the patients were in terms of the usual criteria, nor whether the drugs they were receiving, ie, methylxanthines, could have contributed to the GER. In addition, there was no attempt to correlate GER with asthma status because the authors felt these children stabilized in the residential setting. Future studies need to not only establish the prevalence of GER in asthmatic children, but attempt to better characterize the type of patients who would be the best candidates for diagnosis and treatment. Finally, the effect of therapy needs to be assessed in terms of both GER and asthma to help establish a cause-and-effect relationship.