Variation between pragmatic and standardised blood pressure measurements in a Nigerian primary care clinic

Background: A significant difference in the blood pressure (BP) value of a patient taken by different health workers has been a subject of discussion among health workers. This study investigated the variations between usual-care and guideline-concordant BP measurement protocols and evaluated the implications of the disparities on diagnosis and treatment decision. Methods: A cross-sectional study was conducted among 206 participants. The usual-care and guideline-concordant BP readings taken from each participant by the regular clinic nurses and research-trained nurses, respectively, were obtained. Results: Majority of the regular clinic nurses following the usual-care protocol used the left arm for BP measurement (59.7%). The systolic BP (SBP) and diastolic BP (DBP) readings were higher on the right arm in 55.3% and 39.2% of the participants, respectively. The mean guideline-concordant BP was 7.67 mmHg higher than the mean usual-care for SBP (p = 0.05) and 7.14 mmHg higher for DBP (p = 0.05). The proportion of participants classified as having hypertension and uncontrolled BP was 11.8% and 15.0% lower when using usual-care BP compared to guideline-concordant BP, respectively. Fifty-one (24.8%) respondents were advised incorrect treatment based on usual-care BP measurement. The Bland-Altman plot showed that limits of agreement were wider than within the 10 mmHg clinical reference range and unacceptable for clinical purposes. Conclusion: The usual-care and guideline-concordant BP measurement protocols were significantly different, and the disparity had significant consequences on the diagnosis and treatment of hypertension. Health workers should strictly adhere to the guidelines on BP measurement to avoid mismanagement of patients.