Impact of achieved systolic blood pressure on renal function in hypertensive patients

There is strong evidence for the association of high blood pressure (BP) with depressed renal function. Although high BP at baseline is associated with greater progression of chronic kidney disease (CKD), randomized trials in CKD patients have found no significant relationship between more intensive BP control and glomerular filtration rate (GFR) decline. However, the relationship of GFR and change in GFR over time to lower achieved systolic BP (SBP) in hypertensive patients undergoing treatment is unclear.

Baseline estimated GFR (eGFR) and change in eGFR during follow-up were examined in relation to average on-treatment SBP in 8778 hypertensive patients with ECG left ventricular hypertrophy (LVH) randomly assigned to losartan- or atenolol-based treatment. GFR was estimated using the Modification of Diet in Renal Disease study equation. Patients with average on-treatment SBP ≤130 mmHg (lowest quintile at last measurement) and average SBP between 131 and 141 mmHg were compared with patients with average SBP ≥142 mmHg (median SBP at last measurement). Patients with an average on-treatment SBP ≤130 mmHg had significantly lower baseline eGFR than those with average SBP between 131 and 141 or average SBP ≥142 mmHg (65.5 ± 14.3 vs. 69.3 ± 14.3 vs. 69.0 ± 14.5 mL/min/1.73 m2, P < 0.001 using analysis of covariance adjusting for age, sex, race, randomized treatment, prior antihypertensive treatment, history of diabetes, myocardial infarction, ischaemic heart disease or heart failure, smoking status, baseline serum glucose, total and HDL cholesterol, albuminuria, and baseline LVH by Cornell product and Sokolow-Lyon voltage). However, the decrease in eGFR between baseline and Year 4 was significantly lower among patients with average SBP ≤130 mmHg (-6.3 ± 10.3 vs. -7.9 ± 11.1 vs. -9.2 ± 10.6 mL/min/1.73 m2, P = 0.001 when adjusting for the same variables and for change in Cornell product and Sokolow-Lyon voltage between baseline and Year 4). These differences in eGFR change persisted even after adjusting for baseline eGFR, and there were no significant interactions with randomized treatment, sex, race, or baseline presence of proteinuria.

Lower average on-treatment SBP (≤130 mmHg) was associated with a lower baseline eGFR but with a slower reduction in eGFR during 4-year follow-up in hypertensive patients with ECG LVH, independent of other possible risk factors for decreased GFR. Further study is necessary to determine whether randomized treatment to lower SBP goals is more protective of renal function than treatment to standard SBP goals.

http://clinicaltrials.gov/ct/show/NCT00338260?order=1; unique identifier: NCT00338260.