Affiliation:
1. Department of Epidemiology, University of Groningen, University Medical Center Groningen , Groningen , The Netherlands
2. Department of Preventive Medicine, Shantou University Medical College , Shantou, Guangdong , PR China
3. Department of Internal Medicine, Division of Nephrology, University of Groningen, University Medical Center Groningen , Groningen , The Netherlands
Abstract
Abstract
BACKGROUND
Previous studies have found associations of red blood cell (RBC) traits (hemoglobin and RBC count) with blood pressure; whether these associations are causal is unknown.
METHODS
We performed cross-sectional analyses in the Lifelines Cohort Study (n = 167,785). Additionally, we performed bidirectional 2 sample Mendelian randomization (MR) analyses to explore the causal effect of the 2 traits on systolic (SBP) and diastolic blood pressure (DBP), using genetic instrumental variables regarding hemoglobin and RBC identified in UK Biobank (n = 350,475) and International Consortium of Blood Pressure studies for SBP and DBP (n = 757,601).
RESULTS
In cross-sectional analyses, we observed positive associations with hypertension and blood pressure for both hemoglobin (odds ratio [OR] = 1.18, 95% confidence interval [CI]: 1.16–1.20 for hypertension; B = 0.11, 95% CI: 0.11–0.12 for SBP; B = 0.11, 95% CI: 0.10–0.11 for DBP, all per SD) and RBC (OR = 1.14, 95% CI: 1.12–1.16 for hypertension; B = 0.11, 95% CI: 0.10–0.12 for SBP; B = 0.08, 95% CI: 0.08–0.09 for DBP, all per SD). MR analyses suggested that higher hemoglobin and RBC cause higher DBP (inverse-variance weighted B = 0.11, 95% CI: 0.07–0.16 for hemoglobin; B = 0.07, 95% CI: 0.04–0.10 for RBC, all per SD). Reverse MR analyses (all per SD) suggested causal effects of DBP on both hemoglobin (B = 0.06, 95% CI: 0.03–0.09) and RBC (B = 0.08, 95% CI: 0.04–0.11). No significant effects on SBP were found.
CONCLUSIONS
Our results suggest bidirectional causal relationships of hemoglobin and RBC with DBP, but not with SBP.
Funder
China Scholarship Council
Publisher
Oxford University Press (OUP)