Health benefits of intensive blood pressure control outweigh a slight risk of developing kidney disease
A new study found that in people who do not have chronic kidney disease (CKD), an intensive blood pressure control regimen increases risk of declining kidney function; this risk is generally outweighed by a reduced risk for cardiovascular events and death. Elevated blood pressure is relatively common in the U.S. population and is a risk factor for heart disease, stroke, and kidney disease. The Systolic Blood Pressure Intervention Trial (SPRINT) was designed to test whether using medications to reduce systolic blood pressure to a lower goal than currently recommended will reduce cardiovascular disease risk in people with high blood pressure but not diabetes. (“Systolic” refers to the higher of the two numbers in a blood pressure reading; it measures the pressure in the arteries when the heart beats. “Diastolic” refers to the lower of the two numbers and measures the blood pressure when the heart rests between beats).
SPRINT researchers previously reported that among the subset of study participants who did not have CKD at the start of the trial, those who received an intensive blood pressure control regimen for more than 3 years were at a slightly higher risk of developing CKD than those who received a standard blood pressure control regimen. Researchers have now followed up on this initial observation by performing a more detailed analysis of SPRINT data to understand the broader health benefits and risks of intense blood pressure control. The scientists analyzed data from more than 6,600 study participants without CKD, about one-third of whom were women, to determine the rates of CKD development, cardiovascular events, and death after about 3 years. The scientists defined new-onset CKD as a reduction in kidney function of at least a 30 percent, to a level of function considered less than normal. In the intensive group, 3.7 percent of participants developed CKD as compared to 1.0 percent in the standard group. The researchers also found that 4.9 percent of the intensive group experienced cardiovascular events or death, compared to 7.1 percent in the standard group. Further computational analysis of these data revealed that when compared with standard care, intensive blood pressure control led to a 2.6 percent increase in risk of developing CKD, but the risk of death or of cardiovascular events decreased by 2.2 percent. Through their calculations, the scientists predicted that statistically, for each death or cardiovascular event prevented by the intensive therapy regimen, there would be 1.2 cases of new-onset CKD.
In the intensive group, the reasons for and long-term consequences of the observed reduction in kidney function remain unclear. The researchers point out that because kidney filtration rates are dependent on blood pressure, reduced kidney function to some degree would be expected. Because cardiovascular events and, of course, death are far more serious outcomes, the health benefits of intensive blood pressure therapy outweigh the risk of developing CKD. However, the scientists note that additional follow-up time will help in understanding the longer-term risks and benefits of the two blood pressure control regimens described in the study. They also caution that in some cases, intensive therapy might not be the best option for blood pressure control because the risk of CKD development could be a higher priority than other health considerations. These findings, which add to those from other SPRINT studies, could help provide valuable insights that inform decisions made by patients and health care providers.