Age and Outcomes Associated with BP in Patients with Incident CKD

Abstract

Background and objectives: Hypertension is the most important treatable risk factor for cardiovascular outcomes. Many patients with CKD are elderly, but the ideal BP in these individuals is unknown.

Design, setting, participants, & measurements: From among 339,887 patients with incident eGFR<60 ml/min per 1.73 m(2), we examined associations of systolic BP (SBP) and diastolic BP (DBP) with all-cause mortality, incident coronary heart disease (CHD), ischemic strokes, and ESRD from the time of developing CKD until the end of follow-up (July 26, 2013, for mortality, CHD, and stroke, and December 31, 2011, for ESRD) in multivariable-adjusted survival models categorized by patients' age.

Results: Of the total cohort, 300,424 (88%) had complete data for multivariable analysis. Both SBP and DBP showed a U-shaped association with mortality. SBP displayed a linear association with CHD, stroke, and ESRD, whereas DBP showed no consistent association with either. SBP>140 mmHg was associated with higher incidence of all examined outcomes, but with an incremental attenuation of the observed risk in older compared with younger patients (P<0.05 for interaction) The adjusted hazard ratios and 95% confidence intervals associated with SBP≥170 mmHg (compared with 130-139 mmHg) in patients <50, 50-59, 60-69, 70-79, and ≥80 years were 1.95 (1.34 to 2.84), 2.01 (1.75 to 2.30), 1.68 (1.49 to 1.89), 1.39 (1.25 to 1.54), and 1.30 (1.17 to 1.44), respectively. The risk of incident CHD, stroke, and ESRD was incrementally higher with higher SBP in patients aged <80 years but showed no consistent association in those aged ≥80 years (P<0.05 for interaction for all outcomes).

Conclusions: In veterans with incident CKD, SBP showed different associations in older versus younger patients. The association of higher SBP with adverse outcomes was present but markedly reduced in older individuals, especially in those aged ≥80 years. Elevated DBP showed no consistent association with vascular outcomes in patients with incident CKD.

Keywords: blood pressure; chronic kidney disease; clinical epidemiology; follow-up studies; humans; hypertension; incidence; kidney failure, chronic; renal insufficiency, chronic; risk factors.