Reproducibility of measurements of blood pressure in a tropical environment

The reproducibility of measurements of the blood pressure of 65 adult male Gambians was investigated to assess the role that replication of measurements may have in epidemiological studies in a tropical environment. Observations were made at approximately seven week intervals over a period of 15 months and measurements were repeated three times on each occasion a subject was seen. The magnitude of the variation of an individual subject's BP between occasions, and between readings on the same occasion, was comparable with those which have been observed in studies in developed countries in temperate climates. The variation between occasions was greater than that between readings on the same occasion. There was a significant fall in systolic pressure between the first and third occasions, and a more gradual fall in diastolic pressure. The observations suggest that an individual subject's BP level would be better characterized by making a second reading on another occasion than by making three or more readings on the same occasion. These results have implications for the design of epidemiological studies and for the diagnosis of hypertension in the tropics.