Effects of Intensive Blood Pressure Control on Chronic Kidney Disease Risk
Background of Blood Pressure Measurement
In a follow-up analysis of the SPRINT study, researchers investigated the impact of intensive blood pressure control on the development of chronic kidney disease. Blood pressure is measured in two levels: the systolic blood pressure (SBP) during heart contraction and the diastolic blood pressure (DBP) during heart relaxation. Normal resting blood pressure is defined as an SBP of up to 120 mmHg and a DBP of up to 80 mmHg. Consistently elevated blood pressure may harm organs, increasing the risk of heart disease, stroke, and kidney disease.
Role of Antihypertensive Medications
Antihypertensive medications are utilized to lower blood pressure and mitigate the risk of organ damage. Research indicates that SBP is a more critical risk factor for cardiovascular disease compared to DBP. Nevertheless, the optimal target level for SBP during treatment remains ambiguous, with variations likely necessary for different patient subgroups based on their medical history. Additionally, the advantages of more aggressive treatment must be weighed against potential side effects from higher dosages of antihypertensive medications.
Overview of the SPRINT Study
The SPRINT Study (Systolic Blood Pressure Intervention Trial) aimed to assess the effects of intensive SBP control—where medication was adjusted monthly to maintain an SBP below 120 mmHg—versus standard SBP control, which targeted an SBP between 135-139 mmHg. Conducted among patients without diabetes or prior strokes, the trial was terminated early after approximately three years due to significant reductions in heart attack, stroke, and cardiovascular-related mortality associated with intensive SBP control.
Concerns Regarding Kidney Function
Despite the cardiovascular benefits, concerns arose regarding the potential impact of intensive SBP control on kidney function, as kidney filtration depends heavily on hydrostatic pressure. The SPRINT Study revealed that participants undergoing intensive SBP treatment faced a 3.5-fold increased risk of developing signs of chronic kidney disease.
Subgroup Analysis Findings
The investigators analyzed a subgroup of 6,662 SPRINT participants who initially showed no signs of kidney disease. Kidney health was assessed through glomerular filtration rate tests. After three years, chronic kidney disease signs appeared in 3.7% of the intensive control group, compared to 1% in the standard therapy group. Notably, none of those with chronic kidney disease progressed to end-stage kidney failure, and approximately 25% of those in the intensive group regained kidney function. Conversely, the intensive treatment group exhibited a 4.9% incidence of cardiovascular events or mortality, compared to 7.1% in the standard treatment group.
Conclusions and Future Considerations
The researchers concluded that while intensive treatment elevated the risk of chronic kidney disease, this risk was overshadowed by the benefits of reduced cardiovascular events and overall mortality. However, the long-term effects of aggressive SBP management on kidney function remain to be determined. Clinicians must carefully balance the benefits of intensive SBP management with the potential adverse effects stemming from increased antihypertensive medications in individual patients.
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Reference
Beddhu S, Rocco MV, Toto R, et al. Effects of intensive systolic blood pressure control on kidney and cardiovascular outcomes in persons without kidney disease. Ann Int Med. 2017;167:375-383. doi:10.7326/M16-2966.