Aspects of the use of relative risk models in the design and analysis of cohort studies and prevention trials

First report on genome wide association study in western Indian population reveals host genetic factors for COVID-19 severity and outcome

Different human races across the globe responded in a different way to the SARS-CoV-2 infection leading to different disease severity. Therefore, it is anticipated that host genetic factors have a straight association with the COVID-19. We identified a total 6, 7, and 6 genomic loci for deceased-recovered, asymptomatic-recovered, and deceased-asymptomatic group comparison, respectively. Unfavourable alleles of the markers nearby the genes which are associated with lung and heart diseases such as Tumor necrosis factor superfamily (TNFSF4&18), showed noteworthy association with the disease severity and outcome for the COVID-19 patients in the western Indian population. The markers found with significant association with disease prognosis or recovery are of value in determining the individual's response to SARS-CoV-2 infection and can be used for the risk prediction in COVID-19. Besides, GWAS study in other populations from India may help to strengthen the outcome of this study.

Dihydroceramide- and ceramide-profiling provides insights into human cardiometabolic disease etiology

Metabolic alterations precede cardiometabolic disease onset. Here we present ceramide- and dihydroceramide-profiling data from a nested case-cohort (type 2 diabetes [T2D, n = 775]; cardiovascular disease [CVD, n = 551]; random subcohort [n = 1137]) in the prospective EPIC-Potsdam study. We apply the novel NetCoupler-algorithm to link a data-driven (dihydro)ceramide network to T2D and CVD risk. Controlling for confounding by other (dihydro)ceramides, ceramides C18:0 and C22:0 and dihydroceramides C20:0 and C22:2 are associated with higher and ceramide C20:0 and dihydroceramide C26:1 with lower T2D risk. Ceramide C16:0 and dihydroceramide C22:2 are associated with higher CVD risk. Genome-wide association studies and Mendelian randomization analyses support a role of ceramide C22:0 in T2D etiology. Our results also suggest that (dh)ceramides partly mediate the putative adverse effect of high red meat consumption and benefits of coffee consumption on T2D risk. Thus, (dihydro)ceramides may play a critical role in linking genetic predisposition and dietary habits to cardiometabolic disease risk.

Major bleeding during oral anticoagulant therapy associated with factor V activation by factor Xa

OBJECTIVE

Plasma thrombin generation (TG) provides important information on coagulation status; however, current TG output parameters do not predict major bleeding of patients on anticoagulants. We recently reported that factor V (FV) activation by factor X (FX)a contributes importantly to the initiation phase of TG. Here we investigated how this pathway varies in the normal population and whether FXa-mediated activation of FV is associated with major bleeding in patients on anticoagulant therapy.

APPROACH

We employed TIX-5, a specific inhibitor of FV activation by FXa, to estimate the contribution of FXa-mediated FV activation to tissue factor (TF)-initiated TG.

RESULTS

We show that the contribution of this pathway to plasma TG varies considerably in the normal population, as measured by the time needed to form the first traces of thrombin (TG lag time; mean prolongation by TIX-5 40%, range 0%-116%). Comparing patients on vitamin K antagonists (VKA) of the BLEED study (263 patients with and 538 patients without major bleeding), showed a marked prolongation in the median TG lag time in the presence of TIX-5 in cases (12.83 versus 11.00 minutes, P = 0.0030), while the TG lag time without TIX-5 only showed a minor although significant difference (5.83 vs. 5.67 minutes, P = 0.0198). The TIX-5 sensitivity (lag time + TIX-5/lag time + vehicle) in the upper quartile was associated with a 1.62-fold (95% confidence interval 1.04-2.52) increased risk of major bleeding compared to the lowest quartile.

CONCLUSION

A greater dependence on FXa-mediated activation of FV of TG is associated with increased risk of major bleeding during VKA therapy.

Metals and Breast Cancer Risk: A Prospective Study Using Toenail Biomarkers

The role of metals in breast cancer is of interest because of their carcinogenic and endocrine-disrupting capabilities. Evidence from epidemiologic studies remains elusive, and prior studies have not investigated metal mixtures. In a case cohort nested within the Sister Study (enrolled in 2003-2009; followed through September 2017), we measured concentrations of 15 metals in toenails collected at enrollment in a race/ethnicity-stratified sample of 1,495 cases and a subcohort of 1,605 women. We estimated hazard ratios and 95% confidence intervals for each metal using Cox regression and robust variance. We used quantile g-computation to estimate the joint association between multiple metals and breast cancer risk. The average duration of follow-up was 7.5 years. There was little evidence supporting an association between individual metals and breast cancer. An exception was molybdenum, which was associated with reduced incidence of overall breast cancer risk (third tertile vs. first tertile: hazard ratio = 0.82, 95% confidence interval: 0.67, 1.00). An inverse association for antimony was observed among non-Hispanic Black women. Predefined groups of metals (all metals, nonessential metals, essential metals, and metalloestrogens) were not strongly associated with breast cancer. This study offers little support for metals, individually or as mixtures, as risk factors for breast cancer. Mechanisms for inverse associations with some metals warrant further study.

Conducting Real-world Evidence Studies on the Clinical Outcomes of Diabetes Treatments

Real-world evidence (RWE), the understanding of treatment effectiveness in clinical practice generated from longitudinal patient-level data from the routine operation of the healthcare system, is thought to complement evidence on the efficacy of medications from randomized controlled trials (RCTs). RWE studies follow a structured approach. (1) A design layer decides on the study design, which is driven by the study question and refined by a medically informed target population, patient-informed outcomes, and biologically informed effect windows. Imagining the randomized trial we would ideally perform before designing an RWE study in its likeness reduces bias; the new-user active comparator cohort design has proven useful in many RWE studies of diabetes treatments. (2) A measurement layer transforms the longitudinal patient-level data stream into variables that identify the study population, the pre-exposure patient characteristics, the treatment, and the treatment-emergent outcomes. Working with secondary data increases the measurement complexity compared to primary data collection that we find in most RCTs. (3) An analysis layer focuses on the causal treatment effect estimation. Propensity score analyses have gained in popularity to minimize confounding in healthcare database analyses. Well-understood investigator errors, like immortal time bias, adjustment for causal intermediates, or reverse causation, should be avoided. To increase reproducibility of RWE findings, studies require full implementation transparency. This article integrates state-of-the-art knowledge on how to conduct and review RWE studies on diabetes treatments to maximize study validity and ultimately increased confidence in RWE-based decision making.

Association of the odd-chain fatty acid content in lipid groups with type 2 diabetes risk: A targeted analysis of lipidomics data in the EPIC-Potsdam cohort

BACKGROUND

Plasma odd-chain saturated fatty acids (OCFA) are inversely associated with type 2 diabetes (T2D) risk and may serve as biomarkers for dairy fat intake. Their distribution across different lipid classes and consequences for diabetes risk remain unknown.

AIM

To investigate the prospective associations of OCFA-containing lipid species with T2D risk and their dietary determinants.

METHODS

Within the European Prospective Investigation into Cancer and Nutrition-Potsdam study (n = 27,548), we applied a nested case-cohort design (subcohort: n = 1,248; T2D cases: n = 820; median follow-up 6.5 years). OCFA-containing lipids included triacylglycerols, free fatty acids (FFA), cholesteryl esters (CE), phosphatidylcholines, phosphatidylethanolamines, lysophosphatidylcholines, lysophosphatidylethanolamines, monoacylglycerols, and diacylglycerols. We estimated lipid class-specific associations between OCFA-containing lipids and T2D in sex-stratified Cox proportional-hazards models. We investigated correlations between lipids and dietary intakes derived from food-frequency questionnaires.

RESULTS

We observed heterogeneous integration of OCFA in different lipid classes: triacylglycerols, FFA, CE, and phosphatidylcholines contributed most to the total OCFA-plasma abundance. The relative concentration of OCFA was particularly high in monoacylglycerols, and the contribution of C15:0 versus C17:0 to the total OCFA-abundance differed across lipid classes. In women, several OCFA-containing phospholipids were inversely associated with T2D risk [phosphatidylcholine(C15:0), HR Q5 vs Q1: 0.56, 95% CI 0.32-0.97; phosphatidylcholine(C17:0), HR per SD: 0.59, 95% CI 0.48-0.71; lysophosphatidylcholine(C17:0), HR Q5 vs Q1: 0.42, 95% CI 0.23-0.76]. In men, we did not detect statistically significant inverse associations in phospholipids, and lysophosphatidylcholine(C15:0) was associated with higher T2D risk (HR Q5 vs. Q1: 1.96, 95% CI 1.06-3.63). Besides, CE(C17:0), monoacylglycerols(C15:0), and diacylglycerols(C15:0) were inversely associated with T2D risk; FFA(C17:0) was positively associated with T2D risk in women. Consumption of fat-rich dairy and fiber-rich foods were positively and red meat inversely correlated to OCFA-containing lipid plasma levels.

CONCLUSIONS

OCFA-containing lipids are linked to T2D risk in a lipid class and sex-specific manner, and they are correlated with several foods.

Vascular injury biomarkers and stroke risk

Objective

Because little is known about associations between biomarkers of vascular injury and stroke risk, we evaluated associations between plasma concentrations of 6 novel biomarkers of vascular injury and stroke risk in a population-based study.

Methods

A case–cohort subset of EPIC-Heidelberg (European Prospective Investigation for Cancer and Nutrition–Heidelberg) including incident stroke cases (n = 335) and a random subcohort (n = 2,418) was selected. Concentrations of intercellular adhesion molecule 3 (ICAM3), soluble E-selectin and P-selectin, soluble thrombomodulin (sTM), thrombopoietin, and glycoprotein IIb/IIIa were measured in baseline plasma samples. Weighted Cox regression analyses were used to assess associations between biomarker levels and stroke risk.

Results

Median follow-up in the subcohort and among cases was 9.8 (range, 0.1–12.5) years and 6.2 (range, 0.01–12.1) years, respectively. ICAM3 levels were associated with increased risk of incident stroke after multivariable adjustment (hazard ratio, highest vs lowest quartile: 1.64 [95% confidence interval, 1.15–2.32]; plinear trend < 0.001). This association was more apparent for ischemic (1.65 [1.12–2.45]; plinear trend < 0.01) than for hemorrhagic stroke (1.29 [0.60–2.78]; plinear trend = 0.3). We further observed a borderline significant trend for a positive association between sTM and overall stroke risk (1.47 [0.99–2.19]; plinear trend = 0.05).

Conclusions

In this population-based study, circulating levels of ICAM3, an adhesion molecule shed by leukocytes, were associated with increased risk of incident stroke. Further mechanistic studies are needed to elucidate the pathophysiology underlying this association.

Classification of evidence

This study provides Class II evidence that plasma levels of ICAM3 are associated with increased stroke risk.

Associations of short stature and components of height with incidence of type 2 diabetes: mediating effects of cardiometabolic risk factors

AIMS/HYPOTHESIS

This study aimed to evaluate associations of height as well as components of height (sitting height and leg length) with risk of type 2 diabetes and to explore to what extent associations are explainable by liver fat and cardiometabolic risk markers.

METHODS

A case-cohort study within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study comprising 26,437 participants who provided blood samples was designed. We randomly selected a subcohort of 2500 individuals (2029 diabetes-free at baseline and with anamnestic, anthropometrical and metabolic data for analysis). Of the 820 incident diabetes cases identified in the full cohort during 7 years of follow-up, 698 remained for analyses after similar exclusions.

RESULTS

After adjustment for age, potential lifestyle confounders, education and waist circumference, greater height was related to lower diabetes risk (HR per 10 cm, men 0.59 [95% CI 0.47, 0.75] and women 0.67 [0.51, 0.88], respectively). Leg length was related to lower risk among men and women, but only among men if adjusted for total height. Adjustment for liver fat and triacylglycerols, adiponectin and C-reactive protein substantially attenuated associations between height and diabetes risk, particularly among women.

CONCLUSIONS/INTERPRETATION

We observed inverse associations between height and risk of type 2 diabetes, which was largely related to leg length among men. The inverse associations may be partly driven by lower liver fat content and a more favourable cardiometabolic profile.

Biomarkers of Vascular Injury and Type 2 Diabetes: A Prospective Study, Systematic Review and Meta-Analysis

Data on biomarkers of vascular injury and type 2 diabetes (T2D) risk from prospective studies are lacking. We evaluated seven biomarkers of vascular injury in relation to T2D. Additionally, a meta-analysis was performed. From the EPIC–Heidelberg cohort, 2224 participants were followed-up from baseline for 16 (median) years. E-Selectin, P-Selectin, intercellular adhesion molecule 3 (ICAM3), thrombomodulin, thrombopoietin, glycoprotein IIb/IIIa and fibrinogen levels were measured in baseline blood samples. The systematic review and meta-analysis included prospective studies identified through MEDLINE and Web of Science that investigated the association between mentioned biomarkers and T2D. The study population included 55% women, median age was 50 years, and 163 developed T2D. ICAM3 was associated with lower T2D risk (fully adjusted HR_{highest vs. lowest} tertile 0.62 (95% CI: 0.43, 0.91)), but no other studies on ICAM3 were identified. Overall, fifteen studies were included in the systematic review and meta-analysis (6,171 cases). E-Selectin was associated with higher T2D risk HR_{per SD}: 1.34 (95% CI: 1.16, 1.54; I² = 63%, n = 9 studies), while thrombomodulin was associated with lower risk HR_{per SD}: 0.82 (95% CI: 0.71, 0.95; I² = 0%, n = 2 studies). In the EPIC–Heidelberg, ICAM3 was associated with lower T2D risk. The meta-analysis showed a consistent positive association between E-Selectin and T2D. It was also suggestive of an inverse association between thrombomodulin and T2D, although further studies are needed to corroborate this finding.

Carotid artery displacement and cardiovascular disease risk in the Multi-Ethnic Study of Atherosclerosis

Novel technology permits quantification of common carotid artery (CCA) displacement, which is traditionally ignored. We evaluated associations with CCA displacement and cardiovascular disease (CVD) risk and events in a large, multi-ethnic cohort. Right CCA longitudinal displacement (LD), transverse displacement (TD), and grayscale median (GSM) were evaluated using ultrasound speckle-tracking and texture analysis software in 2050 participants. Regression analyses were used to define relationships between CCA LD, TD, GSM, and CVD risk factors. Cox proportional hazards models were used to assess relationships between LD, TD, and incident CVD events. Participants were mean (SD) 64 (10) years old. There were 791 cases with a CVD event over a 12-year median follow-up. The mean LD was 0.29 (0.20) mm. In multivariable models including age, sex, race/ethnicity, heart rate, and CVD risk factors, LD was associated positively with active smoking (β = 0.08, p < 0.001) and inversely with black (β = −0.08, p < 0.001), Chinese (β = −0.05, p < 0.001), and Hispanic (β = −0.04, p < 0.05) race/ethnicities relative to white individuals, heart rate (β = −0.03/10 beats/min, p < 0.001), and diastolic blood pressure (β = −0.01/5 mmHg, p < 0.05). In fully adjusted models, LD and TD were associated with GSM ( p < 0.01), but neither predicted incident CVD events (LD: hazard ratio (HR) 0.77 [0.48 to 1.24], p = 0.3; TD: HR 1.12 [0.8 to 1.57], p = 0.5). CCA LD and TD are associated with race/ethnicity and CVD risk factors but not incident CVD events. LD and TD are not measures of arterial stiffness but their association with GSM suggests that lower LD and TD may be related to structural changes within the carotid arterial wall.

Biomarkers of vascular injury in relation to myocardial infarction risk: A population-based study

Little is known about circulating biomarkers of vascular injury in relation to cardiovascular disease risk. Thus, we evaluated associations between six novel markers (E-Selectin, P-Selectin, thrombomodulin, thrombopoietin, intercellular adhesion molecule 3 and GPIIb/IIIa) and established cardiovascular risk factors as well as the risk of myocardial infarction (MI) in a population-based study. Biomarkers were measured in pre-diagnostic plasma samples of a case-cohort subset of EPIC-Heidelberg (incident MI cases: n = 369, random sub-cohort: n = 2,418). Generalized Linear models were used to analyse cross-sectional associations between biomarkers and cardiovascular risk factors. Multivariable Cox Regression analyses were carried out to obtain Hazard Ratios (HRs) of MI across quartiles of biomarkers levels. Cross-sectional analyses showed that sex, smoking, alcohol consumption, diabetes and exogenous hormone use were associated with biomarker levels. However, while fibrinogen was associated with MI risk (HR per standard deviation: 2.97 [95% confidence interval: 1.61, 5.46]), none of the six novel biomarkers was associated with MI risk after multivariable adjustment. In a population-based cohort, biomarkers of vascular injury were associated with established cardiovascular risk factors, but not MI risk. The tested biomarkers may reflect pathophysiological alterations in cardiovascular disease development rather than constituting independent MI risk factors.

Red meat consumption and risk of cardiovascular diseases-is increased iron load a possible link?

Background

High iron load and red meat consumption could increase the risk of cardiovascular diseases (CVDs). As red meat is the main source of heme iron, which is in turn a major determinant of increased iron load, adverse cardiometabolic effects of meat consumption could be mediated by increased iron load.

Objective

The object of the study was to assess whether associations between red meat consumption and CVD risk are mediated by iron load in a population-based human study.

Design

We evaluated relations between red meat consumption, iron load (plasma ferritin), and risk of CVD in the prospective EPIC-Heidelberg Study using a case-cohort sample including a random subcohort (n = 2738) and incident cases of myocardial infarction (MI, n = 555), stroke (n = 513), and CVD mortality (n = 381). Following a 4-step mediation analysis, associations between red meat consumption and iron load, red meat consumption and CVD risk, and iron load and CVD risk were assessed by multivariable regression models before finally testing to which degree associations between red meat consumption and CVD risk were attenuated by adjustment for iron status.

Results

Red meat consumption was significantly positively associated with ferritin concentrations and MI risk [HR per 50 g daily intake: 1.18 (95% CI: 1.05, 1.33)], but no significant associations with stroke risk and CVD mortality were observed. While direct associations between ferritin concentrations and MI risk as well as CVD mortality were significant in age- and sex-adjusted Cox regression models, these associations were substantially attenuated and no longer significant after multivariable adjustment for classical CVD risk factors. Strikingly, ferritin concentrations were positively associated with a majority of classical CVD risk factors (age, male sex, alcohol intake, obesity, inflammation, and lower education).

Conclusion

Increased ferritin concentrations may be a marker of an overall unfavorable risk factor profile rather than a mediator of greater CVD risk due to meat consumption.

Multiple imputation was a valid approach to estimate absolute risk from a prediction model based on case-cohort data

OBJECTIVE

To compare weighting methods for Cox regression and multiple imputation (MI) in a case-cohort study in the context of risk prediction modeling.

STUDY DESIGN AND SETTING

Based on the European Prospective Investigation into Cancer and Nutrition Potsdam study, we estimated risk scores to predict incident type-2 diabetes using full cohort data and case-cohort data assuming missing information on waist circumference outside the case-cohort (∼90%). Varying weighting approaches and MI were compared with regard to the calculation of relative risks, absolute risks, and predictive abilities including C-index, the net reclassification improvement, and calibration.

RESULTS

The full cohort comprised 21,845 participants, and the case-cohort comprised 2,703 participants. Relative risks were similar across all methods and compatible with full cohort estimates. Absolute risk estimates showed stronger disagreement mainly for Prentice and Self & Prentice weighting. Barlow and Langholz & Jiao weighting methods and MI were in good agreement with full cohort analysis. Predictive abilities were closest to full cohort estimates for MI or for Barlow and Langholz & Jiao weighting.

CONCLUSIONS

MI seems to be a valid method for deriving or extending a risk prediction model from case-cohort data and might be superior for absolute risk calculation when compared to weighted approaches.

Amino acids, lipid metabolites, and ferritin as potential mediators linking red meat consumption to type 2 diabetes

BACKGROUND

Habitual red meat consumption was consistently related to a higher risk of type 2 diabetes in observational studies. Potentially underlying mechanisms are unclear.

OBJECTIVE

This study aimed to identify blood metabolites that possibly relate red meat consumption to the occurrence of type 2 diabetes.

DESIGN

Analyses were conducted in the prospective European Prospective Investigation into Cancer and Nutrition-Potsdam cohort (n = 27,548), applying a nested case-cohort design (n = 2681, including 688 incident diabetes cases). Habitual diet was assessed with validated semiquantitative food-frequency questionnaires. Total red meat consumption was defined as energy-standardized summed intake of unprocessed and processed red meats. Concentrations of 14 amino acids, 17 acylcarnitines, 81 glycerophospholipids, 14 sphingomyelins, and ferritin were determined in serum samples from baseline. These biomarkers were considered potential mediators of the relation between total red meat consumption and diabetes risk in Cox models. The proportion of diabetes risk explainable by biomarker adjustment was estimated in a bootstrapping procedure with 1000 replicates.

RESULTS

After adjustment for age, sex, lifestyle, diet, and body mass index, total red meat consumption was directly related to diabetes risk [HR for 2 SD (11 g/MJ): 1.26; 95% CI: 1.01, 1.57]. Six biomarkers (ferritin, glycine, diacyl phosphatidylcholines 36:4 and 38:4, lysophosphatidylcholine 17:0, and hydroxy-sphingomyelin 14:1) were associated with red meat consumption and diabetes risk. The red meat-associated diabetes risk was significantly (P < 0.001) attenuated after simultaneous adjustment for these biomarkers [biomarker-adjusted HR for 2 SD (11 g/MJ): 1.09; 95% CI: 0.86, 1.38]. The proportion of diabetes risk explainable by respective biomarkers was 69% (IQR: 49%, 106%).

CONCLUSION

In our study, high ferritin, low glycine, and altered hepatic-derived lipid concentrations in the circulation were associated with total red meat consumption and, independent of red meat, with diabetes risk. The red meat-associated diabetes risk was largely attenuated after adjustment for selected biomarkers, which is consistent with the presumed mediation hypothesis.

Incidental findings on chest CT imaging are associated with increased COPD exacerbations and mortality

BACKGROUND

This study aimed to evaluate whether incidental CT findings of emphysema, airway thickening and bronchiectasis, as seen on CT scans performed for other non-pulmonary clinical indications, are associated with future acute exacerbations of COPD resulting in hospitalisation or death.

METHODS

This multicentre prospective case-cohort study comprised 6406 subjects who underwent routine diagnostic chest CT for non-pulmonary indications. Using a case-cohort approach, we visually graded CT scans from cases and a random sample of ∼10% of the baseline cohort (n=704) for emphysema severity (range 0-20), airway thickening (range 0-5) and bronchiectasis (range 0-5). We used weighted Cox proportional hazards analysis to assess the independent association between CT findings and hospitalisation or death due to COPD exacerbation.

RESULTS

During a median follow-up of 4.4 years (maximum 5.2 years), 338 COPD events were identified. The risk of experiencing a future acute exacerbation of COPD resulting in hospitalisation or death was significantly increased in subjects with severe emphysema (score ≥7) and severe airway thickening (score ≥3). The respective HRs were 4.6 (95% CI 3.0 to 7.1) and 5.9 (95% CI 3.4 to 10.5). Severe bronchiectasis (score ≥3) was not significantly associated with increased risk of adverse events (HR 1.5; 95% CI 0.9 to 2.5).

CONCLUSIONS

Morphological correlates of COPD such as emphysema and airway thickening detected on CT scans obtained for other non-pulmonary indications are strong independent predictors of subsequent development of acute exacerbations of COPD resulting in hospitalisation or death.

Evaluation of various biomarkers as potential mediators of the association between coffee consumption and incident type 2 diabetes in the EPIC-Potsdam Study

BACKGROUND

The inverse association between coffee consumption and the risk of type 2 diabetes (T2D) is well established; however, little is known about potential mediators of this association.

OBJECTIVE

We aimed to investigate the association between coffee consumption and diabetes-related biomarkers and their potential role as mediators of the association between coffee consumption and T2D.

DESIGN

We analyzed a case-cohort study (subcohort: n = 1610; verified incident T2D cases: n = 417) nested within the European Prospective Investigation into Cancer and Nutrition-Potsdam study involving 27,548 middle-aged participants. Habitual coffee consumption was assessed with a validated, semiquantitative food-frequency questionnaire. We evaluated the association between coffee consumption and several T2D-related biomarkers, such as liver markers (reflected by γ-glutamyltransferase, fetuin-A, and sex hormone-binding globulin), markers of dyslipidemia (high-density lipoprotein cholesterol and triglycerides), inflammation [C-reactive protein (CRP)], an adipokine (adiponectin), and metabolites, stratified by sex.

RESULTS

Coffee consumption was inversely associated with diacyl-phosphatidylcholine C32:1 in both sexes and with phenylalanine in men, as well as positively associated with acyl-alkyl-phosphatidylcholines C34:3, C40:6, and C42:5 in women. Furthermore, coffee consumption was inversely associated with fetuin-A (P-trend = 0.06) and CRP in women and γ-glutamyltransferase and triglycerides in men. Coffee consumption tended to be inversely associated with T2D risk in both sexes, reaching significance only in men [HR (95% CI): women: ≥4 compared with >0 to <2 cups coffee/d: 0.78 (0.46, 1.33); men: ≥5 compared with >0 to <2 cups coffee/d: 0.40 (0.19, 0.81)]. The association between coffee consumption and T2D risk in men was slightly reduced after adjustment for phenylalanine or lipid markers.

CONCLUSIONS

Coffee consumption was inversely associated with a diacyl-phosphatidylcholine and liver markers in both sexes and positively associated with certain acyl-alkyl-phosphatidylcholines in women. Furthermore, coffee consumption showed an inverse trend with CRP in women and with triglycerides and phenylalanine in men. However, these markers explained only to a small extent the inverse association between long-term coffee consumption and T2D risk.

Global DNA methylation and one-carbon metabolism gene polymorphisms and the risk of breast cancer in the Sister Study

Global decrease in DNA methylation is a common feature of cancer and is associated with genomic and chromosomal instability. Retrospective case-control studies have reported that cancer patients have lower global methylation levels in blood DNA than do controls. We used prospectively collected samples and a case-cohort study design to examine global DNA methylation and incident breast cancer in 294 cases and a sample of 646 non-cases in the Sister Study, a study of 50 884 women aged 35-74 years who had not been diagnosed with breast cancer at the time of blood draw. Global methylation in DNA from peripheral blood was assessed by pyrosequencing of the LINE-1 repetitive element. Quartiles of LINE-1 methylation levels were associated with the risk of breast cancer in a dose-dependent fashion (P, trend = 0.002), with an increased risk observed among women in the lowest quartile compared with those in the highest quartile (hazard ratio = 1.75; 95% confidence interval 1.19, 2.59). We also examined 22 polymorphisms in 10 one-carbon metabolism genes in relation to both LINE-1 methylation levels and breast cancer. We found three single-nucleotide polymorphisms in those genes associated with LINE-1 methylation: SLC19A1 (rs1051266); MTRR (rs10380) and MTHFR (rs1537514), one of which was also associated with breast cancer risk: MTHFR (rs1537514). PON1 (rs757158) was associated with breast cancer but not methylation.

Significant associations of the rs2943634 (2q36.3) genetic polymorphism with adiponectin, high density lipoprotein cholesterol and ischemic stroke

BACKGROUND

rs2943634 C/A single nucleotide polymorphism (SNP), located in a non coding region of chromosome 2q36.3, has been associated with coronary artery disease in two genome wide association studies. Our goal was to investigate its relation with myocardial infarction (MI) and ischemic stroke (IS), as well as with 12 intermediate risk phenotypes, in a population-based prospective cohort study.

METHODS

rs2943634 was genotyped in a case-cohort study including a random sample of 1891 individuals (subcohort) and all incident MI (n=211) and IS (n=144) cases during a mean follow-up of 8.2±2.2years, nested within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam cohort comprising 27,548 middle-aged men and women.

RESULTS

rs2943634 minor allele (A) was associated in an additive fashion with lower risk of IS but not with MI [hazard ratio (HR)=0.66; 95% confidence interval (CI): 0.50-0.87; P=0.003; HR=1.02; 95% CI: 0.82-1.28; P=0.83 respectively, for the age and sex adjusted model]. Furthermore, it was related to slightly higher levels of plasma adiponectin [CC 6.94, CA 7.27, AA 7.86μg/ml, P=0.0002] and high density lipoprotein (HDL)-cholesterol (CC 52.08, CA 53.05 and AA 55.27mg/dl, P=0.002), based on additive models. Adjustment for adiponectin and HDL-cholesterol did not attenuate the association between the SNP and IS risk. In contrast, adjustment for adiponectin abolished the association between the SNP and HDL-cholesterol and adjustment for HDL-cholesterol attenuated the association between the SNP and adiponectin.

CONCLUSIONS

Our findings suggest that rs2943634 is associated with IS risk and with plasma levels of HDL-cholesterol and adiponectin in this German population. Further investigations are needed to confirm these results and to clarify the mechanisms underlying the association.

Designing cancer prevention trials: a stochastic model approach

There is growing interest in the design and implementation of cancer prevention trials. The key idea is to have agents which interfere with carcinogenesis and/or the preclinical stage. In this article we develop multi-stage stochastic models for the planning of cancer prevention trials. For known inputs it is possible to calculate the incidence of disease for the control and intervention groups. Consequently we find designs that balance the required sample size and follow-up time while guaranteeing prespecified error probabilities. Moreover such models can incorporate the mode of action of the intervention as well as compliance. The model has been applied to breast cancer to determine the implications for planning breast cancer intervention trials. Although the model addresses issues in cancer prevention, it is quite general and may be suitable for other chronic diseases.

A bibliography and comments on the use of statistical models in epidemiology in the 1980s

This paper reviews developments in statistical modelling in epidemiology in the 1980's, with emphasis on cohort and case-control studies. The central roles of the logistic and proportional hazard models are highlighted, and it is shown how these models lead to a deeper understanding of classical designs and methods of analysis as well as to efficient new designs and analytical procedures. The important area of model misspecification is discussed, including the problems of omitted latent structure, mis-modelling of available measurements, missing data and errors in measurements. Various designs motivated by the logistic model are illustrated numerically, and designs based on the proportional hazards model are discussed, as are papers on sample size determination. There are brief introductions to the literature on other topics, including attributable risk, disease clustering, family studies and genetics, analysis of disease incidence data, infectious disease, longitudinal data, screening and miscellaneous related topics in statistics. An extensive bibliography is indexed according to the outline of the paper.

Estimating hidden morbidity via its effect on mortality and disability

The applicability of the theory of partially observed finite-state Markov processes to the study of disease, morbidity, and disability is explored. A method is developed for the continuous updating of parameter estimates over time in longitudinal studies analogous to Kalman filtering in continuous valued continuous time stochastic processes. It builds on a model of filtering of incompletely observed finite-state Markov processes subject to mortality due to Yashin et al. The method of estimation is based on maximum likelihood theory and the incompleteness in the observation of the process is dealt with by applying missing information principles in maximum likelihood estimation.