By Austin Ulrich, PharmD, BCACP
Clinical Pharmacist Practitioner, UpStream Pharmaceutical Care, Greensboro, NC
SYNOPSIS: Blood pressures obtained in routine clinical practice frequently vary from research-quality blood pressure measurements, highlighting the importance of proper techniques and clinician awareness.
SOURCE: Drawz PE, Agarwal A, Dwyer JP, et al. Concordance between blood pressure in the Systolic Blood Pressure Intervention Trial and in routine clinical practice. JAMA Intern Med 2020;180:1655.
The authors of SPRINT, published in 2015, reported that intensive blood pressure (BP)-lowering in patients with elevated cardiovascular risk (but without diabetes) resulted in lower rates of a composite outcome, including myocardial infarction, other acute coronary syndromes, heart failure, stroke, or death from cardiovascular causes.1 However, BP measurement during the trial was based on an American Heart Association-recommended protocol: BP was measured after five minutes of rest with an automatic oscillometric device, proper patient and BP cuff positioning was ensured, and the obtained BP reading was the mean of three measurements.2 Often, clinicians do not follow these procedures in routine practice, possibly resulting in higher BP readings than would be found using more rigorous protocols.3 This could result in an overestimation of BP level and subsequent overtreatment of hypertension.3
Drawz et al sought to determine the concordance between BP measurements reported in SPRINT under those authors’ protocol and BP measurements for the same patients in routine clinical practice. In this prospective study, the authors evaluated 3,074 patients with three or more trial BP measurements recorded and three or more outpatient BP measurements available in the electronic health record (EHR). The mean age was 68.5 years. Compared with the overall SPRINT population, these patients were more likely to be white, less likely to be women, more likely to be treated with a statin or aspirin, and recorded a lower baseline BP. During the time from the six-month SPRINT visit to the end of the trial, the mean systolic BP was 7.3 mmHg (95% CI, 7.0-7.6 mmHg) and 4.6 mmHg (95% CI, 4.4-4.9 mmHg) lower at trial visits compared with the corresponding outpatient visits for the intensive treatment group and the standard treatment group, respectively. BP differences varied by individual and clinic site, but results generally were consistent for subgroups. However, mean BP differences between outpatient EHR and trial measurements were larger in women compared with men. The authors concluded systolic BP measurements in the routine clinical setting were 5 mmHg to 8 mmHg higher, on average, than systolic BP measurements at SPRINT visits. Additionally, there was a larger systolic BP difference for patients in the intensive treatment group, and variability of BP differences fluctuated at the patient and clinic levels.
This study highlights the need for proper BP monitoring techniques, which tends to be difficult in routine clinical practice for various reasons, including time constraints, lack of staff training or knowledge, limited clinic space, and lack of proper equipment.3 BP measurements are important data points to determine diagnosis and adequate control of hypertension. Patients may be incorrectly diagnosed or treated if clinicians use improper methods. Thus, physicians should be aware of these limitations and consider that without rigorous BP measurement protocol implementation, many routine clinic BP readings can prompt overdiagnosis and overtreatment of hypertension.
Additionally, Drawz et al identified substantial variability between different clinics’ BP measurements and between individual patients’ BP measurements, leading the authors to question the overall validity of using 10 mmHg in national guidelines as a correction factor to approximate clinical trial measurements. In addition to awareness of guideline recommendations and clinical evidence for hypertension management, accounting for patient characteristics, such as comorbid conditions and treatment preferences, can help determine an optimal BP target and treatment regimen.
- The SPRINT Research Group; Wright JT Jr, Williamson JD, Whelton PK, et al. A randomized trial of intensive versus standard blood-pressure control. N Engl J Med 2015;373:2103-2116.
- Muntner P, Shimbo D, Carey RM, et al. Measurement of blood pressure in humans: A scientific statement from the American Heart Association. Hypertension 2019;73:e35-e66.
- Drawz PE, Ix JH. BP measurement in clinical practice: Time to SPRINT to guideline-recommended protocols. J Am Soc Nephrol 2018;29:383-388.