The sphygmomanometer is a well-known device used widely for blood pressure (BP)measurement in primary cares to diagnose hypertension. It is also vastly used by patients to monitor BP for medication. Deviations in measurement might affect significantly the diagnosis. For example, a hypertensive patient might be diagnosed as normal and consequently not receive proper treatment or a healthy patient might be diagnosed as hypertensive and may receive treatment for a nonexistent disease. A measurement has two components, the error and the measurement uncertainty, both affecting the interpretation of the results yielded by the sphygmomanometer. As the impact of measurement uncertainty has not been considered properly, the present study aims to evaluate how it influences the misdiagnosis of hypertension.
A theoretical approach is applied, using two samples from the literature, simulating how the measurement uncertainty affects the diagnosis of a sample with known BP for a sphygmomanometer indicating the threshold pressures of diagnosis. We also carried out a study evaluating how the number of measurements taken affects the probability of misdiagnosis.
For one of the samples, the results show an increase in misdiagnosis of 227% for diastolic pressure and 225% for systolic pressure, considering the threshold of 90 and 140 mmHg, for a measurement error of −5 mmHg when considering a ±5 mmHg uncertainty in comparison with when it is disregarded. The probability of a correct diagnosis also converges to over 98% for four measurements taken.
The significant impact of misdiagnosis is an indicator of the importance of considering the uncertainties as a component to medical decision. The number of measurements taken also plays a major role in hypertension diagnosis.
aDepartment of Legal Metrology, National Institute of Metrology, Quality and Technology – Inmetro
bDepartment of Scientific and Industrial Metrology, Weights and Measures Institute of São Paulo – IPEM-SP, São Paulo, Brazil
Correspondence to Bruno A. Rodrigues Filho, PhD, National Institute of Metrology, Quality and Technology – Inmetro, São Paulo 04122-002, Brazil Tel: +55 113 581 2322; e-mail: email@example.com
Received December 13, 2017
Received in revised form February 8, 2018
Accepted March 27, 2018