Association between magnesium in drinking water and atrial fibrillation incidence: a nationwide population-based cohort study, 2002-2015.

BACKGROUND: Atrial fibrillation (AF) is a common heart rhythm disorder and a risk factor of adverse cardiovascular diseases. Established causes do not fully explain the risk of AF and unexplained risk factors might be related to the environment, e.g. magnesium in drinking water. Low magnesium levels in drinking water might be associated with higher risk of cardiovascular diseases including AF. With detailed individual data from nationwide registries and long-term magnesium exposure time series, we had a unique opportunity to investigate the association between magnesium in drinking water and AF. OBJECTIVE: We evaluated the association between magnesium concentration in drinking water and AF risk. METHODS: A nationwide register-based cohort study (2002-2015) was used including individuals aged ≥30 years. Addresses were linked with water supply areas (n = 2418) to obtain time-varying drinking water magnesium exposure at each address. Five exposure groups were defined based on a 5-year rolling time-weighted average magnesium concentration. AF incidence rate ratios (IRRs) between exposure groups were calculated using a Poisson regression of incidence rates, adjusted for sex, age, and socioeconomic position. Robustness of results was investigated with different exposure definitions. RESULTS: The study included 4,264,809 individuals (44,731,694 person-years) whereof 222,998 experienced an incident AF. Magnesium exposure ranged from 0.5 to 62.0 mg/L (mean = 13.9 mg/L). Estimated IRR (95% CI) compared to the referent exposure group (< 5 mg/L) was 0.98 (0.97-1.00) for the second lowest exposure group (5-10 mg/L), and 1.07 (1.05-1.08) for the two highest exposure groups (15-62 mg/L). Strongest positive associations were observed among those aged ≥80 years and with lowest education group. An inverse association was found among individuals with highest education group. CONCLUSION: There might be a small beneficial effect on AF of an increase in magnesium level in drinking water up to 10 mg/L, though an overall positive association was observed. The unexpected positive association and different associations observed for subgroups suggest a potential influence of unaccounted factors, particularly in vulnerable populations. Future research on magnesium in drinking water and cardiovascular diseases needs to focus on contextual risk factors, especially those potentially correlating with magnesium in drinking water.

Geographical variation and clustering are found in atrial fibrillation beyond socioeconomic differences: a Danish cohort study, 1987-2015.

BACKGROUND: The prevalence and incidence rate of atrial fibrillation (AF) increase worldwide and AF is a risk factor for more adverse cardiovascular diseases including stroke. Approximately 44% of AF cases cannot be explained by common individual risk factors and risk might therefore also be related to the environment. By studying geographical variation and clustering in risk of incident AF adjusted for socioeconomic position at an individual level, potential neighbourhood risk factors could be revealed. METHODS: Initially, yearly AF incidence rates 1987-2015 were estimated overall and stratified by income in a register-based cohort study. To examine geographical variation and clustering in AF, we used both spatial scan statistics and a hierarchical Bayesian Poisson regression analysis of AF incidence rates with random effect of municipalities (n = 98) in Denmark in 2011-2015. RESULTS: The 1987-2015 cohort included 5,453,639 individuals whereof 369,800 were diagnosed with an incident AF. AF incidence rate increased from 174 to 576 per 100,000 person-years from 1987 to 2015. Inequality in AF incidence rate ratio between highest and lowest income groups increased from 23% in 1987 to 38% in 2015. We found clustering and geographical variation in AF incidence rates, with incidence rates at municipality level being up to 34% higher than the country mean after adjusting for socioeconomic position. CONCLUSIONS: Geographical variations and clustering in AF incidence rates exist. Compared to previous studies from Alberta, Canada and the United States, we show that geographical variations exist in a country with free access to healthcare and even when accounting for socioeconomic differences at an individual level. An increasing social inequality in AF was seen from 1987 to 2015. Therefore, when planning prevention strategies, attention to individuals with low income should be given. Further studies focusing on identification of neighbourhood risk factors for AF are needed.

Social inequity in chiropractic utilisation - a cross-sectional study in Denmark, 2010 and 2017.

BACKGROUND: Inequity in healthcare utilisation refers to differences between groups that remain after adjustment for need for health care. To our knowledge, no previous studies have aimed to assess social inequity in chiropractic utilisation in a general population. Therefore, the objective of this study was to evaluate social inequity in chiropractic utilisation in the general Danish population adjusted for health status as a proxy of need for chiropractic care. METHODS: A population-based repeated cross-sectional study design was used based on the Danish National Health Survey in 2010 and 2017. Overall, we included 288,099 individuals aged 30 years or older in 2010 or 2017. For each individual, information on chiropractic utilisation, socioeconomic status, and health status as a proxy of need for chiropractic care was retrieved from nationwide registers using the unique personal identification number. Measures of health status included demographics, poor self-rated physical health, activity limitations, musculoskeletal pain, number of musculoskeletal conditions, and number of chronic diseases. We investigated social inequity in chiropractic utilisation (yes, no) using logistic regression adjusted for health status, stratified by sex and year. Three characteristics of socioeconomic status (educational level, employment status and income) were investigated. To further quantify the degree of social inequity in chiropractic utilisation, we estimated the concentration index of inequity for each of the three characteristics of socioeconomic status. RESULTS: We found significantly higher odds of chiropractic utilisation among individuals with short or medium/long education compared with individuals with elementary education, and among employed individuals compared with individuals who were unemployed, receiving disability pension or retired. Furthermore, the odds of chiropractic utilisation increased with higher income. The concentration index indicated social inequity in chiropractic utilisation in favour of individuals with higher socioeconomic status, with income and employment status contributing more to inequity than educational level. CONCLUSION: The study demonstrated social inequity in chiropractic utilisation in Denmark beyond differences in health status as a proxy of need for chiropractic care in the general population. The results suggest that new strategies are required if equal treatment for equal need is the goal.

Geographical Distribution and Pattern of Pesticides in Danish Drinking Water 2002-2018: Reducing Data Complexity.

Pesticides are a large and heterogenous group of chemicals with a complex geographic distribution in the environment. The purpose of this study was to explore the geographic distribution of pesticides in Danish drinking water and identify potential patterns in the grouping of pesticides. Our data included 899,169 analyses of 167 pesticides and metabolites, of which 55 were identified above the detection limit. Pesticide patterns were defined by (1) pesticide groups based on chemical structure and pesticide-metabolite relations and (2) an exploratory factor analysis identifying underlying patterns of related pesticides within waterworks. The geographic distribution was evaluated by mapping the pesticide categories for groups and factor components, namely those detected, quantified, above quality standards, and not analysed. We identified five and seven factor components for the periods 2002-2011 and 2012-2018, respectively. In total, 16 pesticide groups were identified, of which six were representative in space and time with regards to the number of waterworks and analyses, namely benzothiazinone, benzonitriles, organophosphates, phenoxy herbicides, triazines, and triazinones. Pesticide mapping identified areas where multiple pesticides were detected, indicating areas with a higher pesticide burden. The results contribute to a better understanding of the pesticide pattern in Danish drinking water and may contribute to exposure assessments for future epidemiological studies.

Maternal exposure to arsenic in drinking water and risk of congenital heart disease in the offspring.

INTRODUCTION: Prenatal exposure to arsenic is suspected to impair fetal health, including congenital malformations. Few studies investigated an association between maternal exposure to arsenic and congenital heart disease. OBJECTIVE: To examine the association between maternal exposure to arsenic through drinking water and congenital heart disease among offspring. METHODS: This nationwide cohort study included all liveborn children in Denmark, 1997-2014. Maternal addresses at fetal age 4 weeks were linked to drinking water supply areas. Exposure was arsenic concentration in drinking water in first trimester in four categories (<0.5 µg/L, 0.5-0.9 µg/L, 1.0-4.9 µg/L, ≥5.0 µg/L). Outcomes were defined as congenital heart disease diagnosed within the first year of life, with sub-categorization of severe, septal defects and valvular heart defect. Associations between arsenic levels and congenital heart disease were analysed using logistic regression, presented as odds ratios (OR) with 95% confidence interval (CI), and adjusted for year of birth, mother's educational level and ethnicity. RESULTS: A total of 1,042,413 liveborn children were included of whom 1.0% had a congenital heart disease. The OR of congenital heart disease was higher among children exposed to all levels of arsenic above 0.5 µg/L; the OR was 1.13 (95% CI: 1.08-1.19) for exposure of 0.5-0.9 µg/L, 1.33 (95% CI: 1.27-1.39) for 1.0-4.9 µg/L and 1.42 (95% CI: 1.24-1.63) for ≥5.0 µg/L. Similar associations were observed for congenital septal defects. The OR was also higher for severe congenital heart disease but at the same level among all exposure levels ≥0.5 µg/L. The OR of congenital valvular heart defects was only higher among children with maternal exposure to arsenic in drinking water ≥5.0 µg/L. The associations were similar for boys and girls. CONCLUSION: The findings indicate that maternal exposure to arsenic in drinking water even at low concentrations (i.e., 0.5-0.9 µg/L) increased the risk of congenital heart disease in the offspring.

Implications for cardiac arrest coverage using straight-line versus route distance to nearest automated external defibrillator.

AIM: Quantifying the ratio describing the difference between "true route" and "straight-line" distances from out-of-hospital cardiac arrests (OHCAs) to the closest accessible automated external defibrillator (AED) can help correct likely overestimations in AED coverage. Furthermore, we aimed to examine to what extent the closest AED based on true route distance differed from the closest AED using "straight-line". METHODS: OHCAs (1994-2016) and AEDs (2016) in Copenhagen, Denmark and in Toronto, Canada (2007-2015 and 2015, respectively) were identified. Three distances were calculated between OHCA and target AED: 1) the straight-line distance ("straight-line") to the closest AED, 2) the corresponding true route distance to the same AED ("true route"), and 3) the closest AED based only on true route distance ("shortest true route"). The ratio between "true route" and "straight-line" distance was calculated and differences in AED coverage (an OHCA ≤ 100 m of an accessible AED) were examined. RESULTS: The "straight-line" AED coverage of 100 m was 24.2% (n = 2008/8295) in Copenhagen and 6.9% (n = 964/13916) in Toronto. The corresponding "true route" distance reduced coverage to 9.5% (n = 786) and 3.8% (n = 529), respectively. The median ratio between "true route" and "straight-line" distance was 1.6 in Copenhagen and 1.4 in Toronto. In 26.1% (n = 2167) and 22.9% (n = 3181) of all Copenhagen and Toronto OHCAs respectively, the closest AED in "shortest true route" was different than the closest AED initially found by "straight-line". CONCLUSIONS: Straight-line distance is not an accurate measure of distance and overestimates the actual AED coverage compared to a more realistic true route distance by a factor 1.4-1.6.

Stability of Major Geogenic Cations in Drinking Water-An Issue of Public Health Importance: A Danish Study, 1980⁻2017.

Concentrations and spatial variations of the four cations Na, K, Mg and Ca are known to some extent for groundwater and to a lesser extent for drinking water. Using Denmark as case, the purpose of this study was to analyze the spatial and temporal variations in the major cations in drinking water. The results will contribute to a better exposure estimation in future studies of the association between cations and diseases. Spatial and temporal variations and the association with aquifer types, were analyzed with spatial scan statistics, linear regression and a multilevel mixed-effects linear regression model. About 65,000 water samples of each cation (1980⁻2017) were included in the study. Results of mean concentrations were 31.4 mg/L, 3.5 mg/L, 12.1 mg/L and 84.5 mg/L for 1980⁻2017 for Na, K, Mg and Ca, respectively. An expected west-east trend in concentrations were confirmed, mainly explained by variations in aquifer types. The trend in concentration was stable for about 31⁻45% of the public water supply areas. It is therefore recommended that the exposure estimate in future health related studies not only be based on a single mean value, but that temporal and spatial variations should also be included.