In: Asthma12 Jun 2014
These studies may have been too short to allow the complete benefit from antireflux therapy to become apparent. One surgical series presented 5-year follow-up data indicating an improvement in lung function. One half of the patients in another study were free of respiratory symptoms 77 months after antireflux surgery. Perhaps improvement in pulmonary function would only become apparent in a study that continued medical therapy for years instead of weeks.
Patients may have difficulty distinguishing chest pain of different etiologies canadian drug mall. Esophageal pain, chest wall pain, and angina are frequently confused. Patients may present with chest pain that is initially considered to be due to coronary disease but is subsequently ruled out by coronary angiography and properly attributed to esophageal disease by motility testing or ambulatory pH monitoring. Goodall et al reported a correlation between the severity of GER and asthma symptoms in their subjects. Gustafsson et al found a correlation between the percentage of time that esophageal pH was abnormal before treatment and the improvement in asthma symptoms with ranitidine therapy, even though spirometric values and bronchial reactivity did not improve. Asthma patients may interpret GER symptoms as discomfort due to asthma, accounting for their higher asthma symptom scores and medication use when GER is untreated.
Gastroesophageal reflux may cause dyspnea in otherwise healthy patients with normal lung function and bronchial reactivity. Ambulatory pH monitoring in these patients has shown that dyspnea is temporally related to GER and can be relieved with antireflux therapy. Although the mechanism is unclear, it would not be unreasonable to speculate that if GER causes dyspnea in patients with normal lung function, its effects in asthmatics may be even greater.
Shortcomings of the Studies of Medical Antireflux Therapy in Asthma
The 12 studies of medical antireflux therapy in asthmatics with GER have several design flaws. Three were open studies and one study used an untreated group as a control (Table 1). The absence of a placebo control likely led to an overestimate of the effect of treatment. The importance of the placebo-controlled design is emphasized by the findings of response rates as high as 40% in the placebo or control group in asthma therapy studies. The placebo effect is due to several factors, such as the effects of patient education that includes instruction in proper asthma medication delivery device technique and adherence to prescribed regimens, and the regular medical follow-up that asthmatics receive while participating in research trials. Unless the investigators have used a placebo-controlled group for comparison, it is uncertain whether improvement is due to the effects of treatment or to the benefits of participating in the trial.
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