Cardiovascular Benefits for Blood Donors? A Systematic Review

•Blood donation may protect against cardiovascular disease.•Results on cardiovascular disease events and risk factors were inconsistent.•Quality of included studies was generally poor.•High-quality RCTs or cohort studies are required to draw less biased conclusions. It has been proposed that blood donation could be protective against cardiovascular disease. The aim of this study is to systematically summarize and evaluate existing observational and experimental studies on effects of blood donation on cardiovascular risk and disease in donor and general populations. The electronic databases PubMed and EMBASE were searched until March 2019 for experimental and observational studies on blood donation and cardiovascular risk or disease. Excluded were studies performed in patient populations or with controls compared to a patient population, and studies performed in individuals aged 70. All identified studies were independently screened for eligibility and quality using validated scoring systems by 2 reviewers. A total of 44 studies met all criteria. We included 41 observational studies and 3 experimental studies. 14 studies had a quality assessment score of 7 or higher. Of those, a majority of 9 studies reported a protective effect of blood donation, while 5 studies found no effects on cardiovascular risk factors. Results on other various outcomes were inconsistent and study quality was generally poor. Whether or not blood donation protects against cardiovascular disease remains unclear. Studies showing beneficial effects may have inadequately dealt with the healthy donor effect. High quality studies are lacking and therefore definite conclusions cannot be drawn. Large RCTs or cohort studies of high quality with sufficient follow-up should be conducted to provide evidence on the possible association between blood donation and cardiovascular disease.