The Effect of Intensive vs. Usual Blood Pressure Control on Kidney Function Among Persons With Prior Lacunar Stroke: A Post-Hoc Analysis of the SPS3 Randomized Trial
Background—The effect of intensive blood pressure (BP) lowering on kidney function among persons with established cerebrovascular disease and preserved estimated glomerular filtration rate (eGFR) is not established.
Methods and Results—Among 2610 participants randomized to lower SBP target (<130 mmHg) vs. higher (130-149 mmHg) with repeated measures of serum creatinine, we evaluated differences by study arm in annualized eGFR decline and rapid decline (eGFR decline >30%) using linear mixed models and logistic regression, respectively. We assessed associations of both treatment and kidney function decline with stroke, major vascular events (MVE) and the composite stroke, death, MVE or myocardial infarction, using multivariable Cox regression, separately and jointly including test for interaction. Analyses were conducted by treatment arm. Mean age was 63±11; 949 (36%) were diabetic, mean eGFR was 80±19 ml/min/1.73m2. At 9 months, achieved SBP was 137±15 in higher vs. 127±14 mmHg in lower BP group, and differences were maintained throughout follow-up (mean 3.2 years). Compared with higher, lower BP target had -0.50 (95%CI - 0.79 to -0.21) ml/min/1.73m2/year faster eGFR decline. Differences were most pronounced during the first year (-2.1 ml/min/1.73m2 (95%CI -0.97 to -3.2)), whereas rates of eGFR decline did not differ after year 1 (-0.095, -0.47 to 0.23). A total of 313 (24%) persons in the lower BP group had rapid kidney function decline, compared with 247 (19%) in higher (OR 1.4 (95%CI 1.1 to 1.6)). Differences in rapid decline by treatment arm were apparent in the first year (OR 1.4, 1.1-1.8), but were not significant after year 1 (OR 1.0, 0.73-1.4). Rapid decline was associated with higher risk for stroke, MVE and composite after full adjustment among persons randomized to the higher BP target (Stroke HR 1.93 (1.15 to 3.21), but not the lower BP arm, stroke HR 0.93 (0.50 to 1.75) (all p interaction <0.06).
Conclusions—In persons with prior lacunar stroke and relatively preserved kidney function, intensive BP lowering was associated with greater likelihood of rapid kidney function decline. Differences were primarily observed during the first year of anti-hypertensive treatment. Rapid kidney function decline was not associated with increased risk for clinical events among those undergoing intensive BP lowering.
Clinical Trial Registration Information—ClinicalTrials.gov. Identifier: NCT00059306.
- Received September 30, 2015.
- Revision received December 11, 2015.
- Accepted December 21, 2015.