Assessing hypertension control in the community: the need for follow-up measurements to ensure clinical relevance.

In community surveys of hypertension control the diagnosis is often based on blood pressure measurements taken on only one visit. The clinical diagnosis of hypertension requires demonstration of sustained blood pressure elevation. We conducted a survey that contrasted the results of these two approaches to determining the prevalence of hypertension and the extent to which hypertension is detected and treated. A multistage random sample of 2737 people was selected, examined and interviewed on up to three occasions. Rates of hypertension prevalence and control were computed from data from one, two and three visits. The prevalence of hypertension was overestimated by 30% when the diagnosis was based on data from one rather than three visits, the rates being 149 and 115/1000. The prevalence of undetected hypertension was overestimated by 350%, the rates being 27 and 6/1000. The proportion of subjects with controlled hypertension was underestimated by 23%, at 56%, compared with 73%. These results confirm the need for follow-up measurements to provide a valid assessment of hypertension control in the community.