Adult asthma and gastro-oesophageal reflux: the effects of omeprazole therapy on asthma.

Background: Approximately 40-60% of patients with asthma have gastro-oesophageal reflux (GOR) and it has been postulated that this may worsen asthma severity.

Aims: To investigate the effect of the potent gastric acid inhibitor omeprazole 40 mg orally daily on peak expiratory flow rate (PEFR), asthma symptoms and histamine bronchial responsiveness in adult patients with both asthma and GOR.

Methods: This was a double blind, randomised, placebo controlled, crossover study. Upper gastrointestinal endoscopy, 24 hour oesophageal pH measurements, spirometry and histamine bronchoprovocation test (HIT) were performed prior to entry. Phase 1:2 week placebo run-in period, with baseline recording of PEFR, asthma and GOR symptoms, and use of inhaled beta 2-agonist. Phase 2: patients randomised to receive either placebo or omeprazole 40 mg/d for four weeks. Phase 3: placebo for two weeks. Phase 4: patients crossed over to opposite treatment from that of phase 2. Spirometry, and diary cards were assessed at beginning and end of phases 2 and 4. HIT was performed at the end of phase 2 and at the beginning and end of phase 4.

Results: Twenty patients (eight female and 12 male) completed the study. The evening but not morning PEFR (% predicted) were significantly higher on omeprazole vs placebo (82 +/- 4% SEM vs 79 +/- 4% SEM; p < 0.05). No significant differences were found in FEV1, FVC, histamine bronchial responsiveness and diurnal variation of PEFR between placebo and omeprazole treatments. Similarly, there were no significant differences during placebo and omeprazole periods in day time wheeze, cough, breathlessness, beta 2-agonist use or night time wheeze and breathlessness. Day and night heartburn symptoms were significantly better on omeprazole vs placebo (p < 0.05).

Conclusions: Omeprazole 40 mg daily improved evening PEFR in asthma patients with GOR. However, asthma symptoms, inhaled beta 2-agonist use and histamine bronchial responsiveness did not change.