['Few population-based studies have examined comorbidity in relation to gastro-oesophageal reflux disease (GERD).', 'To study the association between cardiovascular disease, diabetes, gastrointestinal symptoms and GERD.', 'Population-based, cross-sectional, case-control study based on a large Norwegian health survey conducted in 1995-97. Among 65,333 participants, 3153 persons reporting severe reflux symptoms were defined as cases, and 40,210 persons without such symptoms were defined as controls. Data on cardiovascular disease, diabetes, gastrointestinal symptoms and potential confounders were collected through questionnaires. Odds ratios (OR) with 95% confidence intervals (CI) were estimated using unconditional logistic regression, in crude and adjusted models.', 'In the crude models, positive associations were observed between myocardial infarction (OR 1.7, 95% CI 1.4-2.1), angina pectoris (OR 2.5, 95% CI 2.1-2.9) and stroke (OR 1.6, 95% CI 1.2-2.1) and risk of GERD. The associations were attenuated in the adjusted models, but remained significant for angina pectoris (OR 1.9, 95% CI 1.6-2.2). No association was observed between diabetes and GERD. Strong positive associations were seen between all studied gastrointestinal symptoms, i.e. nausea, diarrhoea and constipation, and risk of GERD.'] Are severe symptoms of gastro-oesophageal reflux disease associated with cardiovascular disease and other gastrointestinal symptoms , but not diabetes : a population-based study?