Association of CKD and Stroke Risk Attenuated by Adjustment for Hypertension

Results of studies have suggested that chronic kidney disease (CKD) is an independent predictor of stroke; the studies have proposed various mechanisms for this association. Epidemiological studies have demonstrated that low estimated glomerular filtration rate (eGFR) is a risk factor for stroke independent of cardiovascular risk factors; however, a systematic assessment of the impact of more complete adjustment for blood pressure on the association has been lacking.

Dearbhla Kelly, MB MCh, BAO, MSc, MRCPI, MRCP, and Peter M. Rothwell, MD, PhD, FRCP,  at the University of Oxford, Oxford, United Kingdom, recently conducted a MEDLINE/EMBASE systematic review to February 2018 for cohort studies or randomized controlled trials reporting the incidence of stroke in adults based on baseline eGFR. Results of the review were reported during a poster session at Kidney Week 2019 in a poster titled Does CKD Predict Stroke Rick Independent of Blood pressure? A Systematic Review and Meta-Regression.

The researchers extracted study and participant characteristics and relative risks (RR). A random effects model was used to combine estimates; heterogeneity was assessed with x2 statistics and by subgroup strata and meta-regression.

A total of 168 studies were identified, representing data on 5,611,939 individuals with 115,770 stroke outcomes. The meta-analysis included 85 studies representing 3,417,098 participants with 72,996 stroke events.

The risk of incident stroke was increased among participants with eGFR <60 mL/min/1.73 m2 (RR, 1.73; 95% confidence interval [CI], 1.57-1.90; P<.001). There was substantial heterogeneity between studies (P<.001). Further, following adjustment for cardiovascular risk factors, the association was reduced, with progressive attenuation after additional adjustment for hypertension: single baseline blood pressure measure (RR, 1.63; 95% CI, 1.34-1.99; P<.001); history or treated hypertension (RR, 1.35; 95% CI, 1.24-1.46; P<.001); and multiple blood pressure measurements over months to years (RR, 1.10; 95% CI, 1.02-1.18; P=.01).

In summary, the researchers said, “The apparently independent relationship between CKD and stroke may be confounded by their shared association with long-term prior blood pressure, rendering other proposed mechanisms and related treatments unnecessary.”

Source: Kelly D, Rothwell PM. Does CKD predict stroke risk independent of blood pressure? A systematic review and meta-regression. Abstract of a poster presented at the American Society of Nephrology Kidney Week 2019 (Abstract TH-PO681), November 7, 2019, Washington, DC.