Hypertension guidelines should not reflect suboptimal practice

Editor—T J Scanlon and colleagues point out that blood pressures taken in normal practice may differ from those obtained in clinical trials.1 Their evidence is based on the fact that clinicians in West Sussex used Korotkoff phase IV to measure diastolic blood pressure, while recommended guidelines are based on phase V and are therefore “artificially high.” There has been controversy over whether to use Korotkoff phase IV or phase V since 1912, but current recommendations based on sound epidemiological, therapeutic, and clinicopathological evidence strongly favour the use of phase V.2

Colleagues and I have recently published evidence3 (which was highlighted in an editorial by Peter Rubin4) that phase IV cannot be adequately reproduced between observers. Although our paper primarily concerned pregnancy (for which the use of phase IV has been recommended), we showed …