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.