Association between thyroid function and assessment of hepatic fat and iron contents by magnetic resonance imaging.

The associations of thyroid function parameters with non-alcoholic fatty liver disease (NAFLD) and hepatic iron overload are not entirely clear. We have cross-sectionally investigated these associations among 2734 participants of two population-based cross-sectional studies of the Study of Health in Pomerania. Serum levels of thyroid-stimulating hormone (TSH), free tri-iodothyronine (fT3), and free thyroxine (fT4) levels were measured. Liver fat content (by proton-density fat fraction) as well as hepatic iron content (by transverse relaxation rate; R2*) were assessed by quantitative MRI. Thyroid function parameters were associated with hepatic fat and iron contents by median and logistic regression models adjusted for confounding. There were no associations between serum TSH levels and liver fat content, NAFLD, or hepatic iron overload. Serum fT4 levels were inversely associated with liver fat content, NAFLD, hepatic iron contents, and hepatic iron overload. Serum fT3 levels as well as the fT3 to fT4 ratio were positively associated with hepatic fat, NAFLD, hepatic iron contents, but not with hepatic iron overload. Associations between fT3 levels and liver fat content were strongest in obese individuals, in which we also observed an inverse association between TSH levels and NAFLD. These findings might be the result of a higher conversion of fT4 to the biologically active form fT3. Our results suggest that a subclinical hyperthyroid state may be associated with NAFLD, particularly in obese individuals. Furthermore, thyroid hormone levels seem to be more strongly associated with increased liver fat content compared to hepatic iron content.

Association of sex-specific differences in lipoprotein(a) concentrations with cardiovascular mortality in individuals with type 2 diabetes mellitus.

BACKGROUND: Compared to individuals without type 2 diabetes mellitus, the relative increase in cardiovascular mortality is much higher in women than in men in individuals with type 2 diabetes mellitus. METHODS: We evaluated data from 7443 individuals (3792 women, 50.9%), aged 20 to 81 years, from two independent population-based investigations, SHIP-0 and MONICA/KORA S3. We analyzed the longitudinal sex-specific associations of lipoprotein(a) with cardiovascular mortality in individuals with and without type 2 diabetes mellitus using Cox regression. RESULTS: During a median follow-up of 20.5 years (136,802 person-years), 657 participants (404 men and 253 women) died of cardiovascular causes. Among individuals without type 2 diabetes mellitus, men had a significantly higher risk for cardiovascular mortality compared to women in unadjusted model and after adjustment. On the other hand, in participants with type 2 diabetes mellitus, the risk for cardiovascular mortality was not different between men and women in the unadjusted model and after adjustment for age, body mass index, low-density lipoprotein-cholesterol, fasting status and study sample (SHIP-0, MONICA/KORA S3). Further adjustment for lipoprotein(a) concentrations had no impact on the hazard ratio (HR) for cardiovascular mortality comparing men versus women in individuals without type 2 diabetes mellitus [HR: 1.94; 95% confidence interval (CI) 1.63 to 2.32; p < 0.001]. In individuals with type 2 diabetes mellitus, however, further adjustment for lipoprotein(a) led to an increased risk for cardiovascular mortality in men and a decreased risk in women resulting in a statistically significant difference between men and women (HR: 1.53; 95% CI 1.04 to 2.24; p = 0.029). CONCLUSIONS: Women are described to have a stronger relative increase in cardiovascular mortality than men when comparing individuals with and without type 2 diabetes mellitus. Higher lipoprotein(a) concentrations in women with type 2 diabetes mellitus than in men with type 2 diabetes mellitus might partially explain this finding.

Regional differences of macrovascular disease in Northeast and South Germany: the population-based SHIP-TREND and KORA-F4 studies.

BACKGROUND: Previous studies found regional differences in the prevalence and incidence of type 2 diabetes between Northeast and South of Germany. The aim of this study was to investigate if regional variations are also present for macrovascular disease in people with type 2 diabetes and in the general population. A further aim was to investigate if traditional risk factors of macrovascular complications can explain these regional variations. METHODS: Data of persons aged 30-79 from two regional population-based studies, SHIP-TREND (Northeast Germany, 2008-2012, n = 2539) and KORA-F4 (South Germany, 2006-2008, n = 2932), were analysed. Macrovascular disease was defined by self-reported previous myocardial infarction, stroke or coronary angiography. Multivariable logistic regression was performed to estimate odds ratios (OR) and 95% confidence intervals (CI) for prevalence of macrovascular disease in persons with type 2 diabetes and in the general population. RESULTS: The prevalence of macrovascular disease in persons with type 2 diabetes and in the general population was considerably higher in the Northeast (SHIP-TREND: 32.8 and 12.0%) than in the South of Germany (KORA-F4: 24.9 and 8.8%), respectively. The odds of macrovascular disease in persons with type 2 diabetes was 1.66 (95% CI: 1.11-2.49) in the Northeast in comparison to the South after adjustment for sex, age, body mass index, hypertension, hyperlipidemia and smoking. In the general population, SHIP-TREND participants also had a significantly increased odds of macrovascular disease compared to KORA-F4 participants (OR = 1.63, 95% CI: 1.33-2.00). After excluding coronary angiography (myocardial infarction or stroke only), the ORs for region decreased in all models, but the difference between SHIP-TREND and KORA-F4 participants was still significant in the age- and sex-adjusted model for the general population (OR = 1.34, 95% CI: 1.01-1.78). CONCLUSIONS: This study provides an indication for regional differences in macrovascular disease, which is not explained by traditional risk factors. Further examinations of other risk factors, such as regional deprivation or geographical variations in medical care services are needed.

External quality assessment schemes for glucose measurements in Germany: factors for successful participation, analytical performance and medical impact.

BACKGROUND: Determination of blood glucose concentration is one of the most important measurements in clinical chemistry worldwide. Analyzers in central laboratories (CL) and point-of-care tests (POCT) are both frequently used. In Germany, regular participation in external quality assessment (EQA) schemes is mandatory for laboratories performing glucose testing. METHODS: Glucose testing data from the two German EQAs "Reference Institute for Bioanalytics" (RfB) and "INSTAND - Gesellschaft zur Förderung der Qualitätssicherung in medizinischen Laboratorien" (Instand) were analyzed from 2012 to 2016. Multivariable odds ratios (OR) for the probability to reach a "good" result were calculated. Imprecision and bias were determined and clinical risk of measurement errors estimated. RESULTS: The device employed was the most important variable required for a "good" performance in all EQAs. Additional participation in an EQA for CL automated analyzers improved performance in POCT EQAs. The reciprocal effect was less pronounced. New participants performed worse than experienced participants especially in CL EQAs. Imprecision was generally smaller for CL, but some POCT devices reached a comparable performance. Large lot-to-lot differences occurred in over 10% of analyzed cases. We propose the "bias budget" as a new metric to express the maximum allowable bias that still carries acceptable medical risk. Bias budgets were smallest and clinical risks of errors greatest in the low range of measurement 60-115 mg/dL (3.3-6.4 mmol/L) for most devices. CONCLUSIONS: EQAs help to maintain high analytical performances. They generate important data that serve as the foundation for learning and improvement in the laboratory healthcare system.

Clinical correlates of sex hormones in women: The study of health in Pomerania.

BACKGROUND: Despite associations of sex hormones in women with increased cardiometabolic risk and mortality, the clinical correlates of altered sex hormone concentrations in women are less clearly understood. We investigated a broad range of clinical correlates of sex hormones in women from a large population-based sample. METHODS: Data from 2560 women from two cohorts of the Study of Health in Pomerania were used. Stepwise multivariable regression models were implemented to investigate a broad range of behavioral, socio-demographic, and cardiometabolic clinical correlates related to total testosterone (TT), free testosterone (fT), androstenedione (ASD), dehydroepiandrosterone-sulfate (DHEAS), estrone (E1), estradiol (E2), and sex hormone-binding globulin (SHBG). RESULTS: Waist circumference and BMI (ß-coefficient: -0.03; 95% CI: -0.04; 0.03) were inversely related to SHBG, and BMI was positively related to TT (ß-coefficient: 0.005; 95% CI: 0.001; 0.009), fT, E1, and E2. Smoking was positively related to TT (ß-coefficient: 0.04; 95% CI: 0.01; 0.06), ASD, and fT. Systolic blood pressure (TT: ß-coefficient: 0.002; 95% CI: 0.001; 0.003), hypertension (TT: ß-coefficient: 0.05; 95% CI: 0.003; 0.11), low-density lipoprotein (LDL) cholesterol (TT: ß-coefficient: 0.02; 95% CI: 0.01; 0.05), and total cholesterol (TT: ß-coefficient: -0.03; 95% CI: 0.01; 0.05) were positively related to TT and ASD. Finally, type 2 diabetes mellitus (T2DM), and metabolic syndrome (MetS) were positively related to fT, but inversely related to SHBG. CONCLUSIONS: Our population-based study, with sex hormone concentrations measured by liquid chromatography tandem mass spectrometry, revealed associations between clinical correlates including waist circumference, smoking, cohabitation, systolic blood pressure, cholesterol, and MetS with sex hormones. Thus, sex hormones and SHBG may play a role in the cardiovascular risk profile of women.

Associations of androgens with health care utilization and costs in women-Perspectives of a population-based cohort study.

OBJECTIVE: Despite associations between total testosterone (TT) concentrations and increased cardiometabolic risk, the impact of serum androgens on health care utilization and costs among women is unknown. METHODS: We used data from 1521 women in the population-based cohort Study of Health in Pomerania (SHIP) to investigate the associations of serum TT (measured by liquid chromatography-tandem mass spectrometry), sex hormone-binding globulin (SHBG), and free testosterone (free T) with health care utilization and costs at baseline and five-year follow-up (N=1210), implementing multivariable-adjusted econometric models. RESULTS: Cross-sectional analyses showed no association of TT, SHBG, or free T with hospitalization or total health costs (outpatient as well as inpatient costs). Prospective analyses revealed an inverse association of baseline SHBG with follow-up total health care costs (% change per standard deviation (SD): -26.2%, 95% confidence interval (CI): -42.2%; -8.9%) and inpatient costs (% change per SD: -26.5%%, 95% CI: -45.5%; -2.5%). Baseline free T was positively associated with total health care costs at the five-year follow-up (% change per SD: +37.7%, 95% CI: +4.6%; +81.4%). CONCLUSIONS: In this first cost analysis among women from the general population, we observed no association of androgen serum concentration with health care utilization and costs. However, baseline SHBG appeared to be inversely correlated and free T positively correlated with long-term health care costs.

[The biobank of the German National Cohort as a resource for epidemiologic research]. / Die Biobank der Nationalen Kohorte als Ressource der epidemiologischen Forschung.

BACKGROUND: The linkage of high-quality biosamples with detailed data from medical examinations, questionnaires and interviews offers great opportunities for research. This is particularly true for large-scale prospective epidemiological studies with long observation periods, like the German National Cohort (GNC). AIM: The modalities of collecting, processing and storing biosamples of high quality and with a high throughput, as well as ethical aspects are described using the GNC as an example. MATERIAL AND METHODS: For the GNC, 200,000 randomly selected adults will be recruited by 18 study centres and will be followed up for 20-30 years. In addition to the extensive basic examination protocol, followed by reassessment examinations and follow-up questionnaires, the biorepository is a cornerstone of the GNC. RESULTS: The GNC biorepository will comprise more than 20 million aliquots of plasma, serum, erythrocytes, lymphocytes, urine, saliva, nasal swabs and stool. Preanalytics and aliquoting are performed locally in the study centres and are highly standardised and extensively automated. All samples are stored at - 80 and - 180 °C, respectively. A laboratory information system documents all processing steps and storage locations. Access to data and biosamples will be granted to researchers within and outside Germany after completion of the baseline recruitment (i.e. from 2018 onwards). DISCUSSION: Experience with already existing epidemiological biobanks shows impressive results, especially with regard to genetic research, as well as post-genomics (e.g. transcriptomics, metabolomics, epigenomics). Previous success stories explain the strongly increased demand for data and biosamples from the population. Thus the GNC will provide an important resource for biomedical research in the future.

Factors associated with secondhand smoke exposure prevalence and secondhand smoke level of children living with parental smokers: a cross sectional study.

Factors that might account for the probability of children being exposed to secondhand smoke compared to those who are unexposed and characteristics associated with the urinary cotinine level (UCL) of those who are exposed were investigated. All households in a German region with a child aged 3 years or younger (n = 3,570) were invited to participate in a study that tested the efficacy of an intervention for reducing secondhand smoke exposure. In 1,282 households, at least one parent reported daily smoking. Among these, 915 (71.3%) participated in the study. For data analyses, we used a two-part model. Characteristics of the households associated with SHSE of the youngest child were analyzed, as well as characteristics associated with UCL among those exposed. Exposure to secondhand smoke was defined using a UCL ≥ 10 ng/ml. Secondhand smoke exposure was detected in 57.1% of the samples. Nursery attendance was associated with secondhand smoke exposure, in addition to the number of smokers living in the household, extent of home smoking ban and parental education. Among children exposed, nursery attendance, season of urine collection and age of the child were associated with UCL. Consideration of seasonal smoking behavior and a child's age at the time of intervention may increase attention to the adverse health effects of secondhand smoke exposure.

Association of IGF-I and IGFBP-3 with health care costs and hospitalization: results from a prospective observational study.

OBJECTIVE: Previous cohort studies found robust associations of serum insulin-like growth factor I (IGF-I) and its main binding protein IGFBP-3 with increased morbidity or mortality. This study investigates the relationships between IGF-I and IGFBP-3 with health care costs and hospitalization in a general population and whether adding IGF-I or IGFBP-3 to a model of established health care predictors improves prediction. METHODS: Data from a population-based cohort study of 3139 men and women in Germany, aged 20 to 80 years at baseline were used (median follow-up time: 5.0 years). Self-reported physician visits, length of hospital stay were used to estimate annual costs. IGF-I and IGFBP-3 were categorized at the 10th and 90th percentile, to indicate 'low', 'intermediate', and 'high' concentrations, respectively. RESULTS: Total annual health care costs, with the major component of inpatient costs, and risk of hospitalization at baseline and follow-up were higher in subjects with low compared to intermediate IGF-I or IGFBP-3, after multivariable-adjustment. Subjects with low in contrast to intermediate IGF-I exhibited 30.6% higher annual total costs 5 years after baseline examination, corresponding to a difference in adjusted costs of EUR436.61. CONCLUSIONS: Low IGF-I and IGFBP-3 independently predict future health care costs and hospitalization. IGF-I or IGFBP-3 might be useful to identify subjects with excess health care use. The predictive performance of cross-sectional and longitudinal models of total and inpatient costs were slightly improved by adding IGF-I or IGFBP-3 but the cost-effectiveness of inclusion into prediction models needs to be examined.

Predictive modeling of health care costs: do cardiovascular risk markers improve prediction?

BACKGROUND: To investigate the ability of multiple cardiovascular disease (CVD) markers to predict future health care costs. CVD markers included traditional risk factors (smoking status, body mass index, waist circumference, alcohol intake, diabetes, total : high-density lipoprotein cholesterol ratio, actual hypertension, physical activity) and newer markers (carotid intima-media thickness, hemoglobin A1c, apolipoprotein B : apolipoprotein A-1 ratio, lipoprotein (a), leukocyte count, high-sensitive C-reactive protein, plasma fibrinogen, estimated glomerular filtration rate, urinary albumin : creatinine ratio). DESIGN AND METHODS: The study sample consisted of 2233 participants without history of myocardial infarction, stroke, heart failure, and angina pectoris at baseline (50.6% women; mean age 60.9 years; age range 45-81 years) from the cohort Study of Health in Pomerania, Germany (median follow-up 5 years). RESULTS: Predictive modeling revealed that a basic model with sex, age, years of school education, insurance status, and income explained 0.9% in baseline total cost variation and 1.5% in total cost variation at 5-year follow-up. The incorporation of a combination of significant CVD markers resulted in an increase in the R2 for total costs of 70% at baseline and 69% after 5 years, with a final R2 of 0.030 at baseline and an R2 of 0.048 at 5-year follow-up. CONCLUSION: Our data suggest that for individuals without history of CVD, the simultaneous addition of several CVD risk markers improves predictive modeling of future health care costs beyond that of a model that is based on established health care predictors.

Mortality and serum insulin-like growth factor (IGF)-I and IGF binding protein 3 concentrations.

BACKGROUND: Previous studies provided conflicting results regarding the association of serum IGF-I or IGF-binding protein-3 (IGFBP-3) and mortality. The aim of this study was to assess the relation of IGF-I and IGFBP-3 levels with mortality from all causes, cardiovascular disease (CVD), and cancer in a prospective population-based study. METHODS: From the Study of Health in Pomerania (SHIP) 1988 men and 2069 women aged 20-79 yr were followed up on average 8.5 yr. Causes of deaths were coded according to the International Classification of Diseases, 10th revision. Serum IGF-I and IGFBP-3 levels were determined by chemiluminescence immunoassays and categorized into three groups (low, normal, high) according to the sex- and age-specific 10th and 90th percentiles. RESULTS: Adjusted analyses revealed that men with low but not high IGF-I levels had an almost 2-fold higher risk of all-cause mortality [hazard ratio (HR) 1.92 (95% confidence interval [CI] 1.35; 2.73)], CVD mortality [HR 1.92 (95% CI 1.00; 3.71)], and cancer mortality [HR 1.85 (95% CI 1.00; 3.45)] compared with men with normal IGF-I levels. In women, no association between IGF-I and mortality was found. Moreover, low IGFBP-3 levels were associated with higher all-cause mortality in men [HR 1.87 (95% CI 1.31; 2.64)] and women [HR 1.63 (95% CI 0.96; 2.76)]. CONCLUSIONS: The present study found inverse associations between IGF-I or IGFBP-3 levels and mortality from all causes, CVD, or cancer in men and between IGFBP-3 and all-cause mortality in women.

Methods for measurement of LDL-cholesterol: a critical assessment of direct measurement by homogeneous assays versus calculation.

BACKGROUND: Because LDL-cholesterol (LDL-C) is a modifiable risk for coronary heart disease, its routine measurement is recommended in the evaluation and management of hypercholesterolemia. We critically examine here the new homogeneous assays for direct determination of LDL-C. APPROACH: This review relies on published studies and data of the authors using research and routine methods for LDL-C determination. We review experience with methods from their earlier use in lipid research laboratories through the transition to routine clinical testing and the recent development of homogeneous assays. We focus on comparative evaluations and characterizations and the performance of the assays. CONTENT: Homogeneous assays seem to be able to meet current National Cholesterol Education Program (NCEP) requirements for LDL-C testing for precision (CV <4%) and accuracy (bias <4%), when samples collected from nonfasting individuals are used. In addition, all five currently available assays have been certified by the Cholesterol Reference Methods Laboratory Network. The homogeneous methods also appear to better classify individuals into NCEP cutpoints than the Friedewald calculation. However, the limited evaluations to date raise questions about their reliability and specificity, especially in samples with atypical lipoproteins. CONCLUSIONS: Available evidence supports recommending the homogeneous assays for LDL-C to supplement the Friedewald calculation in those cases where the calculation is known to be unreliable, e.g., triglycerides >4000 mg/L. Before the homogeneous assays can be confidently recommended to replace the calculation in routine practice, more evaluation is needed.