Association of blood pressure with clinical outcomes in older adults with chronic kidney disease

Abstract

Background: in chronic kidney disease (CKD), hypertension is associated with poor outcomes at ages <70 years. At older ages, this association is unclear. We tested 10-year mortality and cardiovascular outcomes by clinical systolic blood pressure (SBP) in older CKD Stages 3 and 4 patients without diabetes or proteinuria.

Methods: retrospective cohort in population representative primary care electronic medical records linked to hospital data from the UK. CKD staged by CKD-EPI equation (≥2 creatinine measurements ≥90 days apart). SBPs were 3-year medians before baseline, with mean follow-up 5.7 years. Cox competing models accounted for mortality.

Results: about 158,713 subjects with CKD3 and 6,611 with CKD4 met inclusion criteria. Mortality increased with increasing CKD stage in all subjects aged >60. In the 70 plus group with SBPs 140-169 mmHg, there was no increase in mortality, versus SBP 130-139. Similarly, SBPs 140-169 mmHg were not associated with increased incident heart failure, stroke or myocardial infarctions. SBPs <120 mmHg were associated with increased mortality and cardiovascular risk. At ages 60-69, there was increased mortality at SBP <120 and SBP >150 mmHg.Results were little altered after excluding those with declining SBPs during 5 years before baseline, or for longer-term outcomes (5-10 years after baseline).

Conclusions: in older primary care patients, CKD3 or 4 was the dominant outcome predictor. SBP 140-169 mmHg having little additional predictive value, <120 mmHg was associated with increased mortality. Prospective studies of representative older adults with CKD are required to establish optimum BP targets.

Keywords: blood pressure; cardiovascular outcomes; chronic kidney disease; older people.