Heartburn and acid regurgitation are the characteristic gastro-oesophageal reflux symptoms (GORS). GORS are associated with reduced quality of life and increased risk of oesophageal adenocarcinoma. GORS are highly prevalent in Western populations, but the changes in prevalence, incidence, and loss of GORS over time are unsettled. Overweight and tobacco smoking are known risk factors of GORS. However, whether weight loss or tobacco smoking cessation improves GORS is unclear. The aims of this thesis were to address changes in the occurrence of GORS in the same population over time and the associations between weight loss and tobacco smoking cessation and improvement in GORS.
Materials and methods
The thesis is based on data from the Nord-Trøndelag Health Study (HUNT), a series of population-based health surveys conducted in Nord-Trøndelag County, Norway. In HUNT 2 (1995 to 1997) and HUNT 3 (2006 to 2009) all adult residents of the county were invited. The participants received questionnaires on several health related topics, including complaints with GORS, and clinical measurements were performed at examination sites. In addition, data on antireflux medication was collected through the Norwegian Prescription Database. The prevalence of any, severe, and at least weekly GORS during HUNT 2 and HUNT 3 and the cumulative incidence and loss of GORS
Epidemiology of gastro-oesophageal reflux between HUNT 2 and HUNT 3 were calculated. The association between weight loss and GORS and between tobacco smoking cessation and GORS was assessed by multivariable logistic regression, providing odds ratios (OR) and 95% confidence intervals (CI), while taking potential confounding factors into consideration.
In HUNT 2 and HUNT 3, 58 869 and 44 997 participants answered the GORS questionnaire, respectively. This corresponded to response rates of 64% and 49%, respectively. Of the HUNT 2 participants, 29 610 individuals were prospectively followed up at HUNT 3, corresponding to a response rate of 61%. During the average 11-year period between 1995 to 1997 and 2006 to 2009, the prevalence of any, severe, and at least weekly GORS increased by 30% (from 31.4% to 40.9%), 24% (from 5.4% to 6.7%), and 47% (from 11.6% to 17.1%), respectively. The average annual incidence of any and severe GORS was 3.07% and 0.23%, respectively. In women, but not men, the incidence of GORS increased with increasing age. The average annual spontaneous loss (not due to antireflux medication) of any and severe GORS was 2.32% and 1.22%, respectively. The spontaneous loss of GORS decreased with increasing age. Weight loss was dose-dependently associated with reduction of GORS and an increased treatment success with antireflux medication. Among individuals with >3.5 units decrease in body mass index (BMI), the OR of loss of any (minor or severe) GORS was 1.98 (95% CI 1.45 to 2.72) when using no or less than weekly antireflux medication, and 3.95 (95% CI 2.03 to 7.65) when using at least weekly antireflux medication. The corresponding ORs of loss of severe GORS was 0.90 (95% CI 0.32 to 2.55) and 3.11 (95% CI 1.13 to 8.58). Among individuals using less than weekly antireflux medication, there was no association between tobacco smoking cessation and improvement in GORS (OR 0.95, 95% CI 0.39 to 2.30). However, when antireflux medication was used at least weekly, cessation of daily tobacco smoking was associated with improvement in GORS from severe to no or minor complaints (OR 1.78, 95% CI 1.07 to 2.97), compared with persistent daily smoking. This association was present among individuals within the normal range of BMI (OR 5.67, 95% CI 1.36 to 23.64), but not among overweight individuals.
Between 1995 to 1997 and 2006 to 2009 the prevalence of GORS increased substantially. At least weekly GORS increased by 47%. The average annual incidence of severe GORS was 0.23%, and the corresponding spontaneous loss was 1.22%. The incidence and spontaneous loss of GORS were influenced by sex and age. Weight loss was dose-dependently associated with both a reduction of GORS and an increased treatment success with antireflux medication. Tobacco smoking cessation was associated with improvement in severe GORS in individuals of normal BMI using at least weekly antireflux medication.