In a predictive model based substudy of the SPRINT trial published in the Journal of American College of Cardiology, Dr. Robert A. Phillips and his colleagues from Houston Methodist Hospital were able to show that patients with a higher 10-year cardiovascular disease (CVD) risk could achieve more benefit than harm from intensive blood pressure control, with a set target of systolic blood pressure (SBP) of < 130mm Hg.
The SPRINT trial had indicated that lowering systolic blood pressure (SBP) to a target below 120 mm Hg compared to the standard target of less than 140 mm Hg reduced the rate of adverse clinical outcomes in non-diabetic patients who had an elevated risk of cardiovascular disease. The net clinical benefit of employing this intensive anti-hypertensive treatment came at the cost of increased serious adverse events (SAEs), including hypotension, syncope, electrolyte imbalances and acute kidney injury.
Subsequently, Phillips et al stratified the population from the SPRINT trial into quartiles based on 10-year CVD risk in order to identify a sub-group that may potentially benefit more from aggressive blood pressure control, with the least amount of harm from serious adverse events (SAEs).
[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]“Our findings support the emerging paradigm of risk-based decisions regarding the intensity of blood pressure treatment. The SPRINT study did not originally account for the level of risk; and therefore, we investigated the impact of baseline level of 10-year cardiovascular risk on the primary outcomes and serious adverse events in SPRINT.”- Dr. Robert Phillips[/perfectpullquote]
The primary outcome was a composite of myocardial infarction, acute coronary syndrome not resulting in myocardial infarction, stroke, acute compensated heart failure or death from cardiovascular causes. The authors then used a predictive model to determine the benefit-to-harm ratio as a function of 10-year CVD risk quartile for SPRINT populations. The results showed that intensive anti-hypertensive treatment in the participants with a 10-year CVD risk of < 18.2 % was associated with a greater harm of SAEs than benefit of reduced primary outcome events (benefit-to-harm ratio <1.00). On the other hand, intensive blood pressure control in those who had a 10-year CVD risk of ≥ 18.2 % had greater benefit than harm (benefit-to-harm ratio >1.00). They were also able to show that as the cardiovascular risk increases, the net clinical benefit also increases. Moreover, the hazard ratios for primary outcome events and all-cause mortality favored the intensive treatment group in all quartiles. The authors concluded that a SBP target of <130 mm Hg would be appropriate for hypertensive individuals with 10-year CVD risk greater than equal to 18.2%.
The substudy under discussion was limited by the lack of data from randomized clinical trials taking CVD risk into account when deciding the intensity of blood pressure control. Secondly, the original population enrolled in the SPRINT trial was not intended to be analyzed by comparing the effectiveness of intensive versus standard treatment based on baseline CVD risk. Echoing these sentiments, Dr. Phillip stated, ” Our findings support the emerging paradigm of risk-based decisions regarding the intensity of blood pressure treatment. The SPRINT study did not originally account for the level of risk; and therefore, we investigated the impact of baseline level of 10-year cardiovascular risk on the primary outcomes and serious adverse events in SPRINT.”
Explaining the impact of the study findings on clinical practice, the authors commented that,”Our findings will spare millions of Americans from unnecessary intensive blood pressure treatment. For patients with 10-year CVD risk between 10% and 18.1%, a standard blood pressure target of <140/90 mm Hg would be appropriate.”