Overweight is a risk factor for both erosive and non-erosive reflux disease.

Introduction: Studies have reported that the association between overweight and erosive oesophagitis is very strong, whilst seeming less consistent with non-erosive reflux disease. Aim: We have hypothesized that this difference may be due to the heterogeneity of endoscopy-negative population. Methods: We studied 81 patients with erosive oesophagitis, 48 controls and 295 endoscopy-negative patients classified by impedance-pH-testing as: (1) pH-POS (abnormal acid exposure); (2) hypersensitive oesophagus (normal acid exposure/SAP+); (3) functional heartburn (normal acid exposure/SAP−). Body mass index was also calculated. Results: Mean body mass index was significantly higher (p < 0.05) in erosive oesophagitis than in endoscopy-negative patients as a whole and controls [27 (18–40) vs. 25 (16–48) vs. 23 (16–34)]. However, the separation of endoscopy-negative patients showed that mean body mass index was higher (p < 0.05) in those with increased acid exposure time [26 (18–45)] than in hypersensitive oesophagus [24 (16–48)]. The former subgroup was similar to erosive oesophagitis, whilst the latter one to both functional heartburn [23 (16–34)] and controls (p = ns). Increased body mass index represented a risk factor for erosive oesophagitis (odds ratio 1.4; 95% confidence interval, 1.2–1.6) and non-erosive reflux disease pH-POS subgroup (odds ratio 1.35; 95% confidence interval, 1.2–1.5). Conclusion: Our study shows that overweight represents an important risk factor for erosive oesophagitis and pH-POS non-erosive reflux disease and not for hypersensitive oesophagus and functional heartburn. This provides an explanation for the previously reported lesser role of this variable in non-erosive reflux disease population.