From 1996 to 1998, 10,537 individuals, aged 20–59 years, registered with seven general practices in Southwest England were enrolled in a community based randomised controlled trial of eradication of Helicobacter pylori (H. pylori). The trial obtained ethics approval from Frenchay Hospital LREC (reference number: 95/83 20/01/1996) and participants provided written informed consent. Participants provided information on the frequency of dyspeptic symptoms experienced in the previous three months, including heartburn ("a burning or ache behind the sternum not due to heart trouble") and acid regurgitation ("a very sour or acid tasting fluid at the back of the throat") using a validated questionnaire [3]. In addition, blood pressure, height, and weight were measured and data on antihypertensive medication, smoking history, alcohol and coffee consumption, and adult social class (derived from current occupation) were collected. The current analysis is based on all participants who tested positive for H. pylori infection (n = 1,634) and a computer generated random sample of H. pylori negative participants (n = 3,268) to give a H. pylori negative to positive ratio of 2:1
Linear regression was used to examine the association between systolic and diastolic blood pressure and the frequency of heartburn and acid regurgitation (daily vs. less frequent). Analyses took account of the clustered nature of the data (by general practice), and the increased sampling of H. pylori positive participants – 33% of participants included in the database, but 15.5% of all participants screened – was dealt with by applying weights that were proportional to the inverse of the sampling fractions. Initial analyses were adjusted for age (years) and sex, while in fully-adjusted analyses we additionally controlled for body mass index (weight(kg)/height2(m), smoking habit (never; ex-smoker; current smoker, <20 a day; current smoker = 20 a day), weekly alcohol intake in units (none; <10; 10–19; = 20), daily coffee consumption in cups (none; 1–4; = 5) and adult social class (manual, non-manual). Similar analyses were conducted to examine whether the frequency of the occurrence of other dyspeptic symptoms (epigastric pain/discomfort, nausea, wind and belching) was associated with blood pressure. Since age-adjusted results were similar for the total sample and the 4,227 (86.2%) individuals with data available on all confounders we report only the latter here. Analyses were carried out using Stata 7.0 (College Station, Texas, USA).