Cost-effectiveness of hypertension treatment: a population-based study

Study sample Power calculations were conducted in the preliminary phase of the study. These suggested that a sample of 1,800 individuals would be required to obtain a prevalence ratio of 1.6 with 80% power and a 5% alpha error for presentations ranging from 25 to 75%. An additional 10% of patients were enrolled to account for potential refusals, and a further 15% to ensure sufficient power for a multivariate analysis. A total of 1,257 families were identified, but 57 did not fulfil the age criterion and 4.5% could not be reached or refused to participate. Thus, the final sample comprised 1,145 families (95.4%) containing 2,177 persons, although only 1,968 (90.4%) were interviewed.