Does iodine fortification affect the risk of atrial fibrillation in incident hyperthyroidism? A national register-based cohort.

OBJECTIVE: Iodine fortification (IF) induces an initial increase followed by a decrease in the incidence of hyperthyroidism in the general population. Within the population of hyperthyroid patients, the sex-, age- and subtype distribution changes after IF. The risk of atrial fibrillation (AF) in hyperthyroid patients may be influenced by these factors. Therefore, we aimed to examine how the association between incident hyperthyroidism and AF was affected by IF increasing the population iodine intake from moderate-mild iodine deficiency to low adequacy. DESIGN, PATIENTS AND MEASUREMENTS: Incident hyperthyroid patients were included at the date of first inpatient or outpatient diagnosis, and AF diagnoses within 3 months before to 6 months after the index date were identified in Danish nationwide registers, 1997-2018. The relative risk (RR) of AF each calendar year (reference: 1997; IF introduced: 2000) was analyzed in Poisson regression models adjusted for age, sex, educational level, geographic region, and comorbidities. RESULTS: Overall, in 62,201 patients with incident hyperthyroidism 7.9% were diagnosed with AF. There was a minor nonsignificantly increased risk of AF during the first years after IF followed by a gradual decrease to RR 0.76 (0.62-0.94) in 2017. There were no statistically significant differences in the development in the risk of AF by sex, age group, or geographic region. CONCLUSIONS: Results indicate that IF may reduce the risk of concomitant AF in hyperthyroid patients. If these results are confirmed, IF may not only reduce the population incidence of hyperthyroidism but also reduce the burden of morbidity in the remaining hyperthyroid patients.

Population-based epidemiology: The Glostrup Population Studies 1964-2021.

The Glostrup Population Studies are population-based cohorts undertaken in the south-western part of Greater Copenhagen since 1964. The participants were randomly selected from the adult general population. The first cohort was established to assess cardiovascular risk factors and, since, the objectives have been broadened to describe and analyse the health of the general population. The studies are health-examination studies with clinical and biochemical data in addition to data from self-administered questionnaires and, in some studies, interviews. Fasting blood and urine samples were collected and stored in our biobank for further studies. Several of the cohorts were performed according to standardized methods in international consortia, hence data have been pooled with other, both Danish and international, cohorts. To date more than 30,000 individuals, both men and women, aged 15-85 years, have participated in The Glostrup Population Studies and participants have been re-examined up to eight times. The data can be used for disease-specific epidemiology, social epidemiology, genetic epidemiology, ageing, lifestyle and health interventions nested within the cohorts. The Glostrup Population Studies represent a great resource; the possibility of merging the different cohorts enables large datasets, as well as trends over time. Furthermore, the long follow-up in both the national registers and with follow-up examinations is unique. The purpose of this commentary is to inform about The Glostrup Population Studies and to invite collaborations to continue utilizing this great resource to combat current and future challenges within health promotion and disease prevention.

Associations of genetic determinants of serum vitamin B12 and folate concentrations with hay fever and asthma: a Mendelian randomization meta-analysis.

BACKGROUND/OBJECTIVES: Studies of the effect of vitamin B12 and folate on the risk of asthma and hay fever have shown inconsistent results that may be biased by reverse causation and confounding. We used a Mendelian randomization approach to examine a potential causal effect of vitamin B12 and folate on hay fever, asthma, and selected biomarkers of allergy by using 11 vitamin B12-associated single-nucleotide polymorphisms (SNPs) and 2 folate-associated SNPs as unconfounded markers. SUBJECTS/METHODS: We included 162,736 participants from 9 population-based studies including the UK Biobank. Results were combined in instrumental variable and meta-analyses and effects expressed as odds ratios (ORs) or estimates with 95% confidence interval (CI). RESULTS: Using genetic proxies for B12 and folate, instrumental variable analyses did not show evidence for associations between serum B12 and hay fever: OR = 1.02 (95% CI: 0.98, 1.05), asthma: OR = 0.99 (95% CI: 0.95, 1.04), allergic sensitization: OR = 1.02 (95% CI: 0.74, 1.40), or change in serum IgE: 10.0% (95% CI: -9.6%, 29.6%) per 100 pg/ml B12. Similarly, there was no evidence for association between serum folate and hay fever: OR = 0.74 (95% CI: 0.45, 1.21), asthma: OR = 0.80 (95% CI: 0.43, 1.49), or allergic sensitization: OR = 1.92 (95% CI: 0.11, 33.45), but there was a statistically significant association with change in serum IgE: 2.0% (95% CI: 0.43%, 3.58%) per 0.1 ng/ml serum folate. CONCLUSIONS: Our results did not support the hypothesis that levels of vitamin B12 and folate are causally related to hay fever, asthma, or biomarkers of allergy, but we found evidence of a positive association between serum folate and serum total IgE.

Multi-frequency bioelectrical impedance analysis (BIA) compared to magnetic resonance imaging (MRI) for estimation of fat-free mass in colorectal cancer patients treated with chemotherapy.

BACKGROUND: Changes in body composition in cancer patients during chemotherapy are associated with treatment related toxicities or mortalities. Thus, it is relevant to identify accessible, relatively inexpensive, portable and reliable tools for evaluation of body composition in cancer patients during the course of their treatments. OBJECTIVE: To examine relationships between single cross-sectional thighs magnetic resonance imaging (MRI), skeletal muscle mass (SM) as reference and multi-frequency bioelectrical impedance analysis (BIA) fat free mass (FFM) in patients with colorectal cancer undergoing chemotherapy. DESIGN: In an observational, prospective study we examine the relationships between single cross-sectional thighs MRI (T1-weighted (1.5 T) SM compared to FFM BIA (8-electrodes multi-frequency Tanita MC780MA)) and FFM skin-fold thickness (ST) (4-points (Harpenden, Skinfold Caliper)) and SM equation for non-obese persons from Lee et al. 2000 (L2000) (based on age, height, weight, sex and race). FFM and SM (kg) were calculated based on either area (MRI) or weight. RESULTS: 18 CRC patients (10 males and 8 females) with mean (SD) age 67 yr (6) were measured at baseline, and 13 were available for follow-up. BIA overestimated FFM kg for all 31 measurements with mean (SD) 18.0 kg (6.0) compared to the MRI. ST overestimated FFM kg with mean 12.4 kg (6.2) and L2000 underestimated SM kg in 18 measurements and overestimated in 13 with a total mean of -4.3 kg (6.8). CONCLUSIONS: BIA and ST were the best alternatives to MRI as they showed constant and thereby correctable errors. The equation, L2000, carried the smallest average measurement error but it was non-constant.