Prevalence of end-digit preference in recorded blood pressure by nurses: a comparison of measurements taken by mercury and electronic blood pressure-measuring devices

Abstract

Objectives: When compared with the use of a mercury sphygmomanometer, the use of a validated digital blood pressure (BP) measuring device eliminates the risk of exposure to mercury. Digital devices are also associated with a lesser degree of end-digit preference (EDP). EDP refers to the occurrence of a particular end digit more frequently than would be expected through chance alone. There have been only a few reports from Africa on the occurrence of EDP in BP measurement. This study examined EDP in BP taken by nurses before and after the introduction of a digital BP-measuring device. Design: The design was a retrospective study. Settings and subjects: We reviewed the BP readings of 458 patients who presented at the dedicated clinic for people living with human immunodeficiency virus/acquired immune deficiency syndrome of Ladoke Akintola University of Technology Teaching Hospital, Osogbo, Nigeria, before and after the introduction of the digital BP-measuring device. Outcome measures: The prevalence of end-digit zero of systolic and diastolic BP readings before and after the introduction of the digital device was compared using McNemar’s test. Results: There was a large and significant fall in end-digit zero when BP readings that were taken using the mercury and digital devices were compared (systolic 98.1% vs. 10.9%, p-value < 0.001; diastolic 97.1% vs. 14.9%, p-value < 0.001 (McNemar’s test). Conclusion: There was a significant reduction in the frequency of end-digit zero when BP was taken with the digital device rather than the mercury device. Regular training and certification of healthcare workers in BP measurement is recommended to ensure a high quality BP measurement standard.