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/m2). 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.