ObjectiveTo investigate the influence of demographic and socioeconomic factors on the COVID-19 case-fatality rate (CFR) globally.DesignPublicly available register-based ecological study.SettingTwo hundred and nine countries/territories in the world.ParticipantsAggregated data including 10 445 656 confirmed COVID-19 cases.Primary and secondary outcome measuresCOVID-19 CFR and crude cause-specific death rate were calculated using country-level data from the Our World in Data website.ResultsThe average of country/territory-specific COVID-19 CFR is about 2%–3% worldwide and higher than previously reported at 0.7%–1.3%. A doubling in size of a population is associated with a 0.48% (95% CI 0.25% to 0.70%) increase in COVID-19 CFR, and a doubling in the proportion of female smokers is associated with a 0.55% (95% CI 0.09% to 1.02%) increase in COVID-19 CFR. The open testing policies are associated with a 2.23% (95% CI 0.21% to 4.25%) decrease in CFR. The strictness of anti-COVID-19 measures was not statistically significantly associated with CFR overall, but the higher Stringency Index was associated with higher CFR in higher-income countries with active testing policies (regression coefficient beta=0.14, 95% CI 0.01 to 0.27). Inverse associations were found between cardiovascular disease death rate and diabetes prevalence and CFR.ConclusionThe association between population size and COVID-19 CFR may imply the healthcare strain and lower treatment efficiency in countries with large populations. The observed association between smoking in women and COVID-19 CFR might be due to the finding that the proportion of female smokers reflected broadly the income level of a country. When testing is warranted and healthcare resources are sufficient, strict quarantine and/or lockdown measures might result in excess deaths in underprivileged populations. Spatial dependence and temporal trends in the data should be taken into account in global joint strategy and/or policy making against the COVID-19 pandemic.

BackgroundThe findings of prospective cohort studies are inconsistent regarding the association between dietary magnesium intake and serum magnesium concentration and the risk of hypertension. We aimed to review the evidence from prospective cohort studies and perform a dose-response meta-analysis to investigate the relationship between dietary magnesium intake and serum magnesium concentrations and the risk of hypertension.MethodsWe searched systematically PubMed, EMBASE and the Cochrane Library databases from October 1951 through June 2016. Prospective cohort studies reporting effect estimates with 95% confidence intervals (CIs) for hypertension in more than two categories of dietary magnesium intake and/or serum magnesium concentrations were included. Random-effects models were used to combine the estimated effects.ResultsNine articles (six on dietary magnesium intake, two on serum magnesium concentration and one on both) of ten cohort studies, including 20,119 cases of hypertension and 180,566 participates, were eligible for inclusion in the meta-analysis. We found an inverse association between dietary magnesium intake and the risk of hypertension [relative risk (RR) = 0.92; 95% CI: 0.86, 0.98] comparing the highest intake group with the lowest. A 100 mg/day increment in magnesium intake was associated with a 5% reduction in the risk of hypertension (RR = 0.95; 95% CI: 0.90, 1.00). The association of serum magnesium concentration with the risk of hypertension was marginally significant (RR = 0.91; 95% CI: 0.80, 1.02).ConclusionsCurrent evidence supports the inverse dose-response relationship between dietary magnesium intake and the risk of hypertension. However, the evidence about the relationship between serum magnesium concentration and hypertension is limited.Electronic supplementary materialThe online version of this article (doi:10.1186/s12937-017-0247-4) contains supplementary material, which is available to authorized users.

OBJECTIVES:Physical fitness may reduce systemic inflammation levels relevant to the risk of symptomatic Crohn's disease (CD) and ulcerative colitis (UC); we assessed if fitness in adolescence is associated with subsequent inflammatory bowel disease (IBD) risk, independent of markers of risk and prodromal disease activity.METHODS:Swedish registers provided information on a cohort of 240,984 men (after exclusions) who underwent military conscription assessments in late adolescence (1969–1976). Follow-up started at least 4 years after the conscription assessment until 31 December 2009 (up to age 57 years). Cox's regression assessed the association of physical fitness with CD (n=986) and UC (n=1,878) in separate models, with adjustment including: socioeconomic conditions in childhood; physical fitness, height, body mass index, and erythrocyte sedimentation rate (ESR) in adolescence; and subsequent diagnoses of IBD.RESULTS:Low fitness was associated with a raised risk of IBD, with unadjusted hazard ratios (and 95% confidence intervals) of 1.62 (1.31–2.00) for CD and 1.36 (1.17–1.59) for UC. The results were attenuated by adjustment, particularly for markers of prodromal disease activity to 1.32 (1.05–1.66) and 1.25 (1.06–1.48), respectively. Raised ESR in adolescence was associated with increased risks for subsequent CD (5.95 (4.47–7.92)) and UC (1.92 (1.46–2.52)).CONCLUSIONS:The inverse association of physical fitness with IBD risk is consistent with a protective role for exercise. However, evidence of disease activity before diagnosis was already present in adolescence, suggesting that some or all of the association between fitness and IBD may be due to prodromal disease activity reducing exercise capacity and therefore fitness.