[The effects of different settings on outcome when screening for high blood pressure.]

It has become increasingly popular to offer blood pressure measurements under circumstances that differ from the usual setting, for example measurements in supermarkets, pharmacies, at exhibitions etc. It is well known that environmental factors as well as doctor and patient relationship can affect blood pressure measurement. This must be considered in the diagnosis and treatment of hypertension. The aim of this study was to evaluate some of these phenomena.

Subjects attending local supermarket in a rural community were offered blood pressure measurement two Friday afternoons. All measurements were done in a sitting position with a fully automatic blood pressure recorder, AND UA-767. Hypertension was diagnosed if blood pres notsure exceeded 140 mm Hg systolic and/or 90 mmHg diastolic (according to WHO standards). Those who had hypertension were followed by two office and six home measurements. For the statistical analysis, a t-test for paired data was used. RESULTS are reported as means.

Total of 125 subjects had their blood pressure measured. By the WHO criteria 64 (51.2%) of the subjects had hypertension. Mean blood pressure was significantly higher in the supermarket compared to office both for systolic, 17.1 (C.I:12.8-21.4)mmHg, and diastolic, 5.2 (0.1:2.7-7.7) mmHg, blood pressure. Eighty per cent of the subjects had normal blood pressure at home. Compared to supermarket the mean blood pressure reduction was 29.3 (0.1:24.7-33.9) mmHg for systolic and 10.1 (0.1:7.2-13.0) mmHg for diastolic. A "white coat effect" (office vs. home BP) was present. Mean blood pressure reduction 12.9 mmHg (0.1:10.1-15.7) mmHg for systolic and 5.0 mmHg (0.1:3.4-6.6) for diastolic.

This unconventional approach to blood pressure screening seems to be both cheap and acceptable for the public. Blood pressure measurements under these circumstances on the other hand are not directly comparable to the standard values given by WHO and should be looked on as reflecting the blood pressure each given time. Environmental factors therefore influence the blood pressure measurement greatly. The interaction between the physician and the patient seems to be a major factor in the office vs. home blood pressure difference, the so called white coat effect. On the other hand there must be another explanation for the difference between blood pressure measurement in supermarket "and at home. Different circumstances and their effect on reference values when offering blood pressure measurements must be taken into consideration. This should be kept in mind when diagnosing hypertension.