Risk subgroups emerge from white-coat hypertension
medwireNews: The prognostic significance of white-coat hypertension varies according to whether all non-office blood pressure (BP) readings are normal, research suggests.
Giuseppe Mancia (University of Milano-Bicocca, Milan, Italy) and team found patients' risk for mortality over follow up lasting 16 years was higher if they had an abnormal reading for either home or ambulatory BP than if both were normal.
In an editorial accompanying the study in Hypertension, Alejandro de la Sierra (University of Barcelona, Terrassa, Spain) warns against "artificial categorization of continuous variables with a continuous relationship to the incidence of complications."
The overall study population comprised 2051 people, of whom 51.9% had normal BP, 23.5% had hypertension, and 24.6% had white-coat hypertension. Patients with white-coat hypertension had an all-cause mortality rate between that of hypertensive and normotensive participants, with cumulative rates of 19.7%, 30.0%, and 6.4%, respectively. There was a similar trend for cardiovascular mortality, although this lost significance after accounting for confounders, whereas the difference in all-cause mortality remained significant.
The team defined white-coat hypertension according to usual clinical practice, so patients had elevated office BP readings, but either their home or ambulatory readings, or both, were normal, effectively placing their BP between that of the normotensive and hypertensive groups.
"In this respect, it is not surprising that they are on an intermediate level of risk of complications between the other 2 groups," says de la Sierra.
However, Mancia et al found that the all-cause mortality rate in the subgroup with "true" white-coat hypertension (normal home and ambulatory readings) was 13.4%, which was not significantly different from rates in the normotensive group after accounting for confounders.
By contrast, the mortality rate was 24.2% among patients who had an abnormal reading for either home or ambulatory BP. This equated to a significant 58% increased mortality risk relative to normotensive participants, after multivariate adjustment, similar to the 48% risk increase among hypertensive patients.
"It would therefore appear that the 3 forms of measuring BP are complementary measurements, enabling us to position patients on a somewhat more precise risk scale than with the use of 1 form of these measurements alone," comments de la Sierra.
"A risk score depending on the degree of elevation of each type of BP measurement method could be more useful than definitions based on the differences between measurements with regard to whether they are normal or elevated."
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By Eleanor McDermid, Senior medwireNews Reporter