Assessment of the Reliability and Validity of Blood Pressure Monitors in Community Pharmacies

Introduction: Measuring blood pressure is a habitual practice in community pharmacies as well as in patients’ homes. Therefore, it is important to have a technique to verify the reliability and validity of blood pressure monitors, both the ones in the pharmacies as well as the ones that users have at home.

Material and methods: For this, we propose and carry out a practical case of assessing reliability using the Bland and Altman technique, and of assessing validity by means of a t-test for matched data and an adaptation of the criteria of the European Society of Hypertension (ESH).

Results: In the practical case we deal with, the monitor assessed was found to be re­liable in comparison with our reference monitor with regard to the SBP as well as the DBP, showing a bias in the DBP, measuring on average 5.1 mmHg more than the reference moni­tor. The monitor assessed did not pass, with regard to ours, the ESH’s validation criteria.

Discussion: As a personal contribution, an Excel^® spreadsheet was created that did all the above-mentioned calculations, including the t-test power, as well as the Bland and Altman graphs on introducing the results of the monitoring in question.