ObjectiveTo systematically review and perform a meta-analysis of radiation associated risks of cardiovascular disease in all groups exposed to radiation with individual radiation dose estimates.DesignSystematic review and meta-analysis.Main outcome measuresExcess relative risk per unit dose (Gy), estimated by restricted maximum likelihood methods.Data sourcesPubMed and Medline, Embase, Scopus, Web of Science Core collection databases.Eligibility criteria for selecting studiesDatabases were searched on 6 October 2022, with no limits on date of publication or language. Animal studies and studies without an abstract were excluded.ResultsThe meta-analysis yielded 93 relevant studies. Relative risk per Gy increased for all cardiovascular disease (excess relative risk per Gy of 0.11 (95% confidence interval 0.08 to 0.14)) and for the four major subtypes of cardiovascular disease (ischaemic heart disease, other heart disease, cerebrovascular disease, all other cardiovascular disease). However, interstudy heterogeneity was noted (P<0.05 for all endpoints except for other heart disease), possibly resulting from interstudy variation in unmeasured confounders or effect modifiers, which is markedly reduced if attention is restricted to higher quality studies or those at moderate doses (<0.5 Gy) or low dose rates (<5 mGy/h). For ischaemic heart disease and all cardiovascular disease, risks were larger per unit dose for lower dose (inverse dose effect) and for fractionated exposures (inverse dose fractionation effect). Population based excess absolute risks are estimated for a number of national populations (Canada, England and Wales, France, Germany, Japan, USA) and range from 2.33% per Gy (95% confidence interval 1.69% to 2.98%) for England and Wales to 3.66% per Gy (2.65% to 4.68%) for Germany, largely reflecting the underlying rates of cardiovascular disease mortality in these populations. Estimated risk of mortality from cardiovascular disease are generally dominated by cerebrovascular disease (around 0.94-1.26% per Gy), with the next largest contribution from ischaemic heart disease (around 0.30-1.20% per Gy).ConclusionsResults provide evidence supporting a causal association between radiation exposure and cardiovascular disease at high dose, and to a lesser extent at low dose, with some indications of differences in risk between acute and chronic exposures, which require further investigation. The observed heterogeneity complicates a causal interpretation of these findings, although this heterogeneity is much reduced if only higher quality studies or those at moderate doses or low dose rates are considered. Studies are needed to assess in more detail modifications of radiation effect by lifestyle and medical risk factors.Systematic review registrationPROSPERO CRD42020202036

Background: Ionizing radiation use for medical diagnostic purposes has substantially increased over the last three decades. Moderate to high doses of radiation are well established causes of cancer, especially for exposure at young ages. However, cancer risk from low-dose medical imaging is debated. Objective: We aim to review the literature on cancer risks associated with prenatal and postnatal medical diagnostic ionizing radiation exposure among children and to assess this risk through a meta-analysis. Methods: A literature search of five electronic databases supplemented by hand search was performed to retrieve relevant epidemiological studies published from 2000 to 2019, including patients aged < 22 years exposed to medical imaging ionizing radiation. Pooled Odds Ratio (OR pooled ) and pooled Excess Relative Risk (ERR pooled ) representing the excess of risk per unit of organ dose were estimated with a random-effect model. Results: Twenty-four studies were included. For prenatal exposure (X-ray or computed tomography (CT)), no significant increased risk for all-cancer, leukemia and brain tumors were reported. For postnatal exposure, increased risks were observed only for CTs, mostly for leukemia: ERR pooled =26.9 Gy -1 (95% confidence interval: 2.7, 57.1) and brain tumors: ERR pooled =9.1 Gy -1 (95% confidence interval: 5.2, 13.1). Conclusion: CT exposure in childhood appears to be associated with increased risks of cancer while no significant association was observed with diagnostic X-rays. Methodological limitations of the studies considered would be handled in upcoming large international studies. Results support optimization efforts to minimize doses to pediatric patients.

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