MEASUREMENT ERROR IN THE HAWKSLEY RANDOM ZERO SPHYGMOMANOMETER - WHATDAMAGE HAS BEEN DONE AND WHAT CAN WE LEARN

The Hawksley random zero sphygmomanometer is used in all aspects of bl ood pressure research, from clinical trials to evaluation of new blood pressure recorders. It is designed to reduce observer bias in blood p ressure measurement. The problem is that it also underestimates blood pressure. Furthermore, this was first reported more than two decades a go. In this paper Ronan Conroy and colleagues explore the consequences of using an inaccurate instrument for important research and why pres tigious organisations like the World Health Organisation continue to u se it.