Unattended Blood Pressure Measurements in the Systolic Blood Pressure Intervention Trial

Abstract

enrolled 9361 participants aged ≥50 years in ≈100 expert medical centers and clinical practices throughout the United States. 1 SPRINT excluded patients with diabetes mellitus and stroke survivors since previous clinical trials included those populations. 2,3 Between 2010 and 2013, the SPRINT investigators randomly allocated the study participants into a standard treatment group receiving an average of 2 different blood pressure (BP) medications to achieve a systolic BP (SBP) target <140 mm Hg and into an intensive treatment group receiving an average of 3 BP medications to achieve a SBP target <120 mm Hg. The Director of the National Heart, Lung, and Blood Institute stopped SPRINT early because of a positive effect. The significant preliminary results of SPRINT were announced on September 11, 2015 4 and the study results were quickly and favorably commented on by the New York Times 5 and the Washington Post. 6 The target SBP <120 mm Hg had reduced rates of the composite primary outcome that included myocardial infarction (MI), other acute coronary syndromes, stroke, heart failure, or death from cardiovascular causes by 25% and the risk of death from all causes by 27%, when compared with the target SBP of <140 mm Hg. The primary results of the trial were presented at the Scientific Sessions of the American Heart Association in Orlando on November 9, 2015 and published on the same day. 7 The SPRINT study was published with an accompanying statement from the Editor of New England Journal of Medicine 8 saying that "This clinical trial will change practice, and we are proud to publish it and to defend the importance of the expedited peer-review and publication process that it has undergone. The report is now in the public domain, and the investigators' data interpretation, analysis, and clinical discussion are open to examination and comment." However, whether the results of the SPRINT study can be implemented into guidelines for the treatment of hypertension and clinical practice for the purpose of aiming at a lower target for SBP than the current SBP target of <140 mm Hg has yet not been settled. In this article, we aimed to review the measurement techniques for BP that was used in SPRINT and assess whether it is representative and applicable for practice outside the specific study. The reason for why we focus on the BP measurement technique in SPRINT is that if it varies substantially from other trials of similar design and aims, the results of SPRINT can only be included into hypertension guidelines and clinical practice with considerable reservation and utmost care. Similarities and differences with the Action to Control Cardiovascular Risk in Diabetes (ACCORD), 2 Secondary Prevention of Small Subcortical Strokes (SPS3), 3 and Hypertension Optimal Treatment (HOT) 9 studies, the other large outcome trials investigating BP targets, are therefore needed to discuss. At present, there are no data from ran-domized outcome-based trials on home and ambulatory blood pressure targets or BP variability. Therefore, a discussion on target blood pressure values in different trials and guidelines can only refer to office blood pressure. Similarities With the ACCORD, SPS3, and HOT Studies The design and the results of SPRINT could in many aspects be compared with those of the US National Institutes of Health sponsored ACCORD study, which randomized hyper-tensive patients with type 2 diabetes mellitus to the same SBP targets as in SPRINT and did not find statistically significant benefit in the intensive treatment group. 2 ACCORD enrolled a study population less than half the size of SPRINT that was younger than the SPRINT population and had normal renal function. Furthermore, ACCORD had a factorial design that included cholesterol and glucose-lowering treatments as well as BP reduction. For all these reasons, ACCORD was statistically underpowered to show a significant benefit of intensive BP reduction. However, ACCORD did show an 11% trend favoring the target SBP <120 mm Hg compared with <140 mm Hg for the composite primary end point and a significant 41% stroke reduction. These results suggest that the From the