The role of gastro-oesophageal pressure gradient and sliding hiatal hernia on pathological gastro-oesophageal reflux in severely obese patients.

BACKGROUND AND AIMS: The relationship between gastro-oesophageal pressure gradient (GOPG), sliding hiatal hernia (SHH) and gastro-oesophageal reflux disease (GORD) is under investigation. We assessed whether GOPG and SHH are predictors of pathological reflux in severely obese patients.
METHODS: Ninety-four consecutive patients were prospectively studied with oesophageal manometry, 24-h pH monitoring, upper gastrointestinal endoscopy and barium swallow X-ray. Inspiratory and expiratory GOPGs were measured at manometry testing, whereas SHH was characterized by X-ray. Patients were classified as having physiological or pathological reflux depending on pH monitoring. Patients with oesophagitis but normal pH testing were excluded.
RESULTS: Eighty-nine patients composed the study sample (25 men, 38.3+/-11.1 years; BMI 45+/-6.9 kg/m). Sixty-two patients (70%) had pathological reflux, whereas 27 patients (30%) had physiological reflux. Pathological reflux was predicted either by inspiratory GOPG [prevalence ratio (PR) =1.05; 95% confidence interval (CI): 1.03-1.08; P<0.001] or by expiratory GOPG (PR=1.07; 95% CI: 1.03-1.11; P=0.001). Accordingly, an increment of 1 mmHg in inspiratory and expiratory GOPGs raises the risk of pathological reflux in 5 and 7%, respectively. Pathological reflux was also predicted by SHH (PR: 1.54, 95% CI: 1.19-2.00; P=0.001), which increases the risk of abnormal reflux in 54%.
CONCLUSION: In severely obese patients, either inspiratory GOPG, expiratory GOPG or SHH are predictors of pathological reflux. These findings give pathophysiological support to the high prevalence of GORD in this population.