Inverse association between plasma chlordecone concentrations and progression of alcoholic liver fibrosis: the role of liver metabolism

BACKGROUND AND AIMS

Chlordecone is a persistent organochlorinated insecticide, extensively used in the French West Indies and has been contaminating the population for more than thirty years. Its potentiation effect on hepatotoxic agents has been demonstrated in animal models. We investigated the relationship between environmental exposure to chlordecone and the progression of liver fibrosis.

METHODS

This study included 182 consecutive patients with chronic alcoholic hepatitis whose liver fibrosis was assessed using non-invasive methods. Measured plasma chlordecone concentrations at inclusion were used as surrogate of long-term exposure under steady-state conditions. As the pharmacokinetic processing of chlordecone is largely determined by the liver, we used a human physiologically based pharmacokinetic model to predict plausible changes in the steady-state blood chlordecone concentrations induced by liver fibrosis.

RESULTS

With a median follow-up of 27.1 years after the onset of alcohol consumption, we found a significant decrease in the risk of advanced liver fibrosis with increasing plasma chlordecone concentration (adjusted hazard ratio = 0.56; 95% confidence interval: 0.34-0.95 for the highest vs. lowest tertile, p = 0.04). Changes induced by liver fibrosis influenced the pharmacokinetic processing of chlordecone, resulting in substantial modifications in its steady-state blood concentrations.

CONCLUSION

According to this human model of coexposure to alcohol, reverse causality is the most plausible explanation of this inverse association between plasma chlordecone concentrations and progression of liver fibrosis. This study underlines the importance of considering the pharmacokinetic of environmental contaminants in epidemiological studies when biomarkers of exposure are used to investigate their own impact on the liver.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03373396.

High blood pressure and colorectal cancer mortality in a 29-year follow-up of the Japanese general population: NIPPON DATA80

Onco-hypertension has been proposed, although associations of high blood pressure (BP) with cancer risk remain inconsistent. We examined associations of high BP with risk of mortality from stomach, lung, colorectal, liver, and pancreatic cancers independent of possible confounders in an analysis that excluded deaths within the first 5 years of follow-up to consider the reverse causality. In a prospective cohort representative of the general Japanese population (1980-2009), we studied 8088 participants (mean age, 48.2 years; 56.0% women) without clinical cardiovascular disease or antihypertensive medication at baseline. Fine-Gray competing risks regression was used to estimate hazard ratios for 10 mmHg higher BP adjusted for confounders including smoking, alcohol-drinking, obesity, and diabetes mellitus. During 29-year follow-up, 159 (2.0%), 159 (2.0%), 89 (1.1%), 86 (1.1%), and 68 (0.8%) participants died from stomach, lung, colorectal, liver, and pancreatic cancers, respectively. We observed a positive association of high BP with risk of colorectal cancer mortality but not with mortality risks from any other cancers. The association with colorectal cancer mortality for systolic and diastolic BP was evident in those aged 30-49 years (hazard ratios 1.43 [95% confidence interval, 1.22-1.67] and 1.86 [1.32-2.62], respectively) but not in those aged 50-59 years and ≥60 years (P for age interaction <0.01 for systolic and diastolic BP). The associations with colorectal cancer mortality were similar in the analyses stratified by smoking, alcohol-drinking, obesity, and diabetic status. In conclusion, high BP among young to middle-aged adults was independently associated with risk of colorectal cancer mortality later in life.

Body mass index and death by cognitive impairment

BACKGROUND

Epidemiological studies have reported that among participants with impaired cognitive, overweight and mild obesity are associated with substantially improved survival, this finding has been termed the "obesity paradox" and has led to uncertainty about secondary prevention.

AIMS

To explore whether the association of BMI with mortality differed in different MMSE score, and whether the obesity paradox in patient with cognitive impairment (CI) is real.

METHODS

The study used data from CLHLS, a representative prospective population-based cohort study in China, which included 8348 participants aged ≥ 60 years between 2011 and 2018. The independent association between BMI and mortality in differed MMSE score by calculating hazard ratios (HRs) in multivariate Cox regression analysis.

RESULTS

During a median (IQR) follow-up of 41.18 months, a total of 4216 participants died. In the total population, underweight increased the risk of all-cause mortality (HRs, 1.33; 95% CI 1.23-1.44), compared with normal weight, and overweight was associated with a decreased risk of all-cause mortality (HR 0.83; 95% CI 0.74-0.93). However,  compared to normal weight, only underweight was associated with increased mortality risk among participants with MMSE scores of 0-23, 24-26, 27-29, and 30, and the fully-adjusted HRs (95% CIs) for mortality were 1.30 (1.18, 1.43), 1.31 (1.07, 1.59), 1.55 (1.34, 1.80) and 1.66 (1.26, 2.20), respectively. The obesity paradox was not found in individuals with CI. Sensitivity analyses carried out had hardly any impact on this result.

CONCLUSION

We found no evidence of an obesity paradox in patients with CI, compared with patients of normal weight. But underweight individuals may have increased mortality risk whether in the population with CI or not. And overweight/obese people with CI should continue to aim for normal weight.

Performance of approaches relying on multidimensional intermediary data to decipher causal relationships between the exposome and health: A simulation study under various causal structures

Challenges in the assessment of the health effects of the exposome, defined as encompassing all environmental exposures from the prenatal period onwards, include a possibly high rate of false positive signals. It might be overcome using data dimension reduction techniques. Data from the biological layers lying between the exposome and its possible health consequences, such as the methylome, may help reducing exposome dimension. We aimed to quantify the performances of approaches relying on the incorporation of an intermediary biological layer to relate the exposome and health, and compare them with agnostic approaches ignoring the intermediary layer. We performed a Monte-Carlo simulation, in which we generated realistic exposome and intermediary layer data by sampling with replacement real data from the Helix exposome project. We generated a Gaussian outcome assuming linear relationships between the three data layers, in 2381 scenarios under five different causal structures, including mediation and reverse causality. We tested 3 agnostic methods considering only the exposome and the health outcome: ExWAS (for Exposome-Wide Association study), DSA, LASSO; and 3 methods relying on an intermediary layer: two implementations of our new oriented Meet-in-the-Middle (oMITM) design, using ExWAS and DSA, and a mediation analysis using ExWAS. Methods' performances were assessed through their sensitivity and FDP (False-Discovery Proportion). The oMITM-based methods generally had lower FDP than the other approaches, possibly at a cost in terms of sensitivity; FDP was in particular lower under a structure of reverse causality and in some mediation scenarios. The oMITM-DSA implementation showed better performances than oMITM-ExWAS, especially in terms of FDP. Among the agnostic approaches, DSA showed the highest performance. Integrating information from intermediary biological layers can help lowering FDP in studies of the exposome health effects; in particular, oMITM seems less sensitive to reverse causality than agnostic exposome-health association studies.

Pharmacokinetic bias analysis of an association between clinical thyroid disease and two perfluoroalkyl substances

Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) has been associated with the occurrence of thyroid disease in some epidemiologic studies. We hypothesized that in a specific epidemiologic study based on the National Health and Nutrition Examination Survey, the association of clinical thyroid disease with serum concentration of PFOA and PFOS was due to reverse causality. Thyroid hormone affects glomerular filtration, which in turn affects excretion of PFOA and PFOS. We evaluated this by linking a model of thyroid disease status over the lifetime to a physiologically based pharmacokinetic model of PFOA and PFOS. Using Monte Carlo methods, we simulated the target study population and analyzed the data using multivariable logistic regression. The target and simulated populations were similar with respect to age, estimated glomerular filtration rate, serum concentrations of PFOA and PFOS, and prevalence of clinical thyroid disease. The analysis showed little or no evidence of bias from the hypothesized mechanism. The largest bias was for the fourth quartile of PFOA in females, with an odds ratio of 0.93 (95% CI, 0.90, 0.97). The reported odds ratio of clinical thyroid disease for this group was 1.63 (1.07, 2.47), and if it were corrected for the bias would have been 1.74 (1.14, 2.65). Our results suggest that little of the reported association in the target study was due to reverse causality.

Using methylome data to inform exposome-health association studies: An application to the identification of environmental drivers of child body mass index

BACKGROUND

The exposome is defined as encompassing all environmental exposures one undergoes from conception onwards. Challenges of the application of this concept to environmental-health association studies include a possibly high false-positive rate.

OBJECTIVES

We aimed to reduce the dimension of the exposome using information from DNA methylation as a way to more efficiently characterize the relation between exposome and child body mass index (BMI).

METHODS

Among 1,173 mother-child pairs from HELIX cohort, 216 exposures ("whole exposome") were characterized. BMI and DNA methylation from immune cells of peripheral blood were assessed in children at age 6-10 years. A priori reduction of the methylome to preselect BMI-relevant CpGs was performed using biological pathways. We then implemented a tailored Meet-in-the-Middle approach to identify from these CpGs candidate mediators in the exposome-BMI association, using univariate linear regression models corrected for multiple testing: this allowed to point out exposures most likely to be associated with BMI ("reduced exposome"). Associations of this reduced exposome with BMI were finally tested. The approach was compared to an agnostic exposome-wide association study (ExWAS) ignoring the methylome.

RESULTS

Among the 2284 preselected CpGs (0.6% of the assessed CpGs), 62 were associated with BMI. Four factors (3 postnatal and 1 prenatal) of the exposome were associated with at least one of these CpGs, among which postnatal blood level of copper and PFOS were directly associated with BMI, with respectively positive and negative estimated effects. The agnostic ExWAS identified 18 additional postnatal exposures, including many persistent pollutants, generally unexpectedly associated with decreased BMI.

DISCUSSION

Our approach incorporating a priori information identified fewer significant associations than an agnostic approach. We hypothesize that this smaller number corresponds to a higher specificity (and possibly lower sensitivity), compared to the agnostic approach. Indeed, the latter cannot distinguish causal relations from reverse causation, e.g. for persistent compounds stored in fat, whose circulating level is influenced by BMI.

Basic and Clinical Pharmaco-Therapeutics of SGLT2 Inhibitors: A Contemporary Update

Clinical relevance of sodium/glucose cotransporter 2 (SGLT2) inhibitors has been rapidly evolving across several therapy areas, apart from type 2 diabetes mellitus. While some of these developments are based on recognized scientific explanations, unexpected study findings have also shaped much of our present understanding. As the role of these agents evolves in various facets of cardiology, nephrology, hepatology and endocrinology, their optimum clinical value propositions should be realized in line with the principles of personalized medicine. An updated pharmaco-ergonomic qualification tool, based on the present evidence with these agents, would be a step in this direction. This review describes the present evidence on diverse pharmacological and therapeutic aspects for various SGLT2 inhibitors, as an attempt to provide useful guidance for optimum application in clinical practice.

Basic and Clinical Pharmaco-Therapeutics of SGLT2 Inhibitors: A Contemporary Update

Clinical relevance of sodium/glucose cotransporter 2 (SGLT2) inhibitors has been rapidly evolving across several therapy areas, apart from type 2 diabetes mellitus. While some of these developments are based on recognized scientific explanations, unexpected study findings have also shaped much of our present understanding. As the role of these agents evolves in various facets of cardiology, nephrology, hepatology and endocrinology, their optimum clinical value propositions should be realized in line with the principles of personalized medicine. An updated pharmaco-ergonomic qualification tool, based on the present evidence with these agents, would be a step in this direction. This review describes the present evidence on diverse pharmacological and therapeutic aspects for various SGLT2 inhibitors, as an attempt to provide useful guidance for optimum application in clinical practice.

Quantitative bias analysis of the association between subclinical thyroid disease and two perfluoroalkyl substances in a single study

Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) has been associated with the occurrence of thyroid disease in some epidemiologic studies. We hypothesized that in a specific epidemiologic study based on the National Health and Nutrition Examination Survey, the association of subclinical thyroid disease with serum concentration of PFOA and PFOS was due to reverse causality. Thyroid hormone affects glomerular filtration, which in turn affects excretion of PFOA and PFOS. We evaluated this by linking a model of thyroid disease status over the lifetime to physiologically based pharmacokinetic models of PFOA and PFOS. Using Monte Carlo methods, we simulated the target study population and analyzed the data using multivariable logistic regression. The target and simulated populations were similar with respect to age, estimated glomerular filtration rate, serum concentrations of PFOA and PFOS, and prevalence of subclinical thyroid disease. Our findings suggest that in the target study the associations with subclinical hypothyroidism were overstated and the results for subclinical hyperthyroidism were, in general, understated. For example, for subclinical hypothyroidism in men, the reported odds ratio per ln(PFOS) increase was 1.98 (95% CI 1.19-3.28), whereas in the simulated data the bias due to reverse causality gave an odds ratio of 1.19 (1.16-1.23). Our results provide evidence of bias due to reverse causality in a specific cross-sectional study of subclinical thyroid disease with exposure to PFOA and PFOS among adults.

Bidirectional associations between food groups and depressive symptoms: longitudinal findings from the Invecchiare in Chianti (InCHIANTI) study

This study investigated bidirectional associations between intake of food groups and depressive symptoms in 1058 Italian participants (aged 20-102 years) of the Invecchiare in Chianti study. Dietary intake, assessed with a validated FFQ, and depressive symptoms, measured with the Center for Epidemiologic Studies Depression scale (CES-D), were assessed at baseline and after 3, 6 and 9 years. Associations of repeated measurements of intakes of thirteen food groups with 3-year changes in depressive symptoms, and vice versa, were analysed using linear mixed models and logistic generalised estimating equations. Fish intake was inversely (quartile (Q)4 v. Q1, B=-0·97, 95 % CI -1·74, -0·21) and sweet food intake positively (Q4 v. Q1, B=1·03, 95 % CI 0·25, 1·81) associated with subsequent CES-D score. In the other direction, higher CES-D scores were associated with decreases in intakes of vegetables (ratio: 0·995, 95 % CI 0·990, 0·999) and red and processed meat (B=-0·006, 95 % CI -0·010, -0·001), an increase in dairy product intake (ratio: 1·008, 95 % CI 1·004, 1·013), and increasing odds of eating savoury snacks (OR: 1·012, 95 % CI 1·000, 1·024). Fruit, nuts and legumes, potatoes, wholegrain bread, olive oil, sugar-sweetened beverages, and coffee and tea were not significantly associated in either direction. Our study confirmed bidirectional associations between food group intakes and depressive symptoms. Fish and sweet food intakes were associated with 3-year improvement and deterioration in depressive symptoms, respectively. Depressive symptoms were associated with 3-year changes in vegetable, meat, dairy product and savoury snack intakes. Trials are necessary to examine the causal associations between food groups and depression.

Associations of depressive symptoms and history with three a priori diet quality indices in middle-aged and older adults

BACKGROUND

Evidence for the diet-depression link is growing but longitudinal studies on the reverse association are scarce. We investigated associations of (1) current depressive symptoms, (2) short-term changes in and (3) long-term history of depressive symptoms with three a priori diet quality indices.

METHODS

Data were from participants (≥ 55 years) of the Longitudinal Aging Study Amsterdam (LASA). The Mediterranean Diet Score (MDS), Alternative Healthy Eating Index (AHEI-2010) and Dietary Approaches to Stop Hypertension diet (DASH) were derived in 2014/2015. Depressive symptoms (Center for Epidemiologic Studies Depression scale; CES-D) were assessed in 2014/2015 and at five regular 3-yearly cycles from 2001-2003 to 2015/2016. Associations between three depression determinants and the diet indices were analysed by multivariable linear regression models.

RESULTS

Cross-sectionally (n = 1312), current depressive symptoms (CES-D ≥ 16) were associated with lower MDS (adjusted B = -1.21, 95%CI = -2.41, -0.023) and AHEI (B = -2.72, 95%CI = -5.24, -0.20) scores in men only. Chronic/recurrent depressive symptoms (CES-D ≥ 16 in both 2011-2013 and 2015/2016) were associated with lower MDS scores (n = 1233; B = -2.22, 95%CI = -3.40, -1.04) and a trend for lower AHEI scores (B = -2.37, 95%CI = -4.92, 0.18), compared to no depressive symptoms (twice CES-D < 16). History of depressive symptoms (ever CES-D ≥ 16 from 2001-2003 to 2011-2013; n = 687) was associated with lower MDS (B = -1.87, 95%CI = -3.47, -0.27) and AHEI (B = -4.33, 95%CI = -7.54, -1.13) scores in men only. No associations were found with the DASH score.

LIMITATIONS

Single dietary data collection impeded investigation of prospective depression-diet associations.

CONCLUSIONS

Our study in middle-aged and older adults suggests that current and past depressive symptoms are associated with poorer diet quality, particularly in men.

The Relationship of Dietary Cholesterol with Serum Low-Density Lipoprotein Cholesterol and Confounding by Reverse Causality: The INTERLIPID Study

Aim: The positive relationship between dietary cholesterol and serum cholesterol has been questioned by a set of recent cohort studies. This study aimed to investigate how employment status and education years relate to the association between dietary cholesterol and serum low-density lipoprotein cholesterol (LDL-C) in a Japanese population.

Methods: A population-based, random sample, cross-sectional study (INTERLIPID) was performed. Among 1,145 Japanese individuals aged 40–59 years, 106 were excluded because of special diets, use of lipid-lowering drugs, hormone replacement, and missing data, leaving 1,039 individuals (533 men and 506 women). Dietary cholesterol was assessed from four 24-h dietary recalls, and LDL-C was measured enzymatically with an autoanalyzer. A standard questionnaire inquired about employment status and education years.

Results: In men, a 1 standard deviation (SD) higher dietary cholesterol was associated with 3.16 mg/dL lower serum LDL-C (P = 0.009; unadjusted model). After adjustment for covariates, higher serum LDL-C was estimated per 1 SD higher intake of dietary cholesterol in nonemployed men [self-employed, homemakers, farmers, fishermen, and retired employees; β = +9.08, 95% confidence interval (CI) = +0.90–+17.27] and less educated men (β = +4.46, 95% CI = −0.97–+9.90), whereas an inverse association was observed in employed men (β = −3.02, 95% CI= −5.49–−0.54) and more educated men (β = −3.66, 95% CI = −6.25–−1.07).

Conclusions: In men who were nonemployed and less educated, a higher intake of dietary cholesterol was associated with elevated concentrations of serum LDL-C, whereas an inverse association was observed in men who were employed and more educated.

Obesity paradox in heart failure: statistical artifact, or impetus to rethink clinical practice?

The "obesity paradox" in heart failure (HF) is a phenomenon of more favorable prognosis, especially better survival, in obese versus normal-weight HF patients. Various explanations for the paradox have been offered; while different in their details, they typically share the premise that obesity per se is not actually the cause of reduced mortality in HF. Even so, there is a lingering question of whether clinicians should refrain from, or at least soft-pedal on, encouraging weight loss among their obese HF patients. Against the backdrop of recent epidemiological analysis by Banack and Kaufman, which speculates that collider stratification bias may generate the obesity paradox, we seek to address the aforementioned question. Following a literature review, which confirms that obese HF patients are demographically and clinically different from their normal-weight counterparts, we present four hypothetical data sets to illustrate a spectrum of possibilities regarding the obesity-mortality association. Importantly, these hypothetical data sets become indistinguishable from each other when a crucial variable is unmeasured or unreported. While thorough, the discussion of these data sets is intended to be accessible to a wide audience, especially including clinicians, without a prerequisite of familiarity with advanced epidemiology. We also furnish intuitive visual diagrams which depict a version of the obesity paradox. These illustrations, along with reflection on the distinction between weight and weight loss (and, furthermore, between voluntary and involuntary weight loss), lead to our recommendation for clinicians regarding the encouragement of weight loss. Finally, our conclusion explicitly addresses the questions posed in the title of this article.

RCTS are the only appropriate way to demonstrate the role of vitamin D in health

Despite thousands of vitamin D studies published, including hundreds of reviews and meta-analyses, it is still uncertain if supplementation with vitamin D will have positive health effects, except for the skeleton. This cannot be answered by doing more observational studies as it is impossible to control for confounding factors and reverse causality. The only way to firmly prove positive vitamin D effects is by doing the properly designed randomized controlled trials (RCTs). However, it has been difficult to show the expected positive effects by vitamin D supplementation in RCTs, which may indicate that the effects, if present must be small. On the other hand, results from Mendelian randomization studies have shown promising results at least for mortality and multiple sclerosis. In the near future, results from several large RCTs with hard endpoints will be available. If these show positive results, the main question on vitamin D and health is answered. If they turn out negative, they will be criticized for having included subjects without vitamin D deficiency, and some studies might not have used an optimal dosing regimen. New and better-designed RCTs will then be needed, but will be very hard to perform.

Cigarette smoking and the association with serous ovarian cancer in African American women: African American Cancer Epidemiology Study (AACES)

BACKGROUND

Smoking is a risk factor for mucinous ovarian cancer (OvCa) in Caucasians. Whether a similar association exists in African Americans (AA) is unknown.

METHODS

We conducted a population-based case-control study of incident OvCa in AA women across 11 geographic locations in the US. A structured telephone interview asked about smoking, demographic, health, and lifestyle factors. Odds ratios and 95% confidence intervals (OR, 95% CI) were estimated from 613 cases and 752 controls using unconditional logistic regression in multivariable adjusted models.

RESULTS

Associations were greater in magnitude for serous OvCa than for all OvCa combined. Compared to never smokers, increased risk for serous OvCa was observed for lifetime ever smokers (1.46, 1.11-1.92), former smokers who quit within 0-2 years of diagnosis (5.48, 3.04-9.86), and for total pack-years smoked among lifetime ever smokers (0-5 pack-years: 1.79, 1.23-2.59; >5-20 pack-years: 1.52, 1.05-2.18; >20 pack-years: 0.98, 0.61-1.56); however, we observed no dose-response relationship with increasing duration or consumption and no significant associations among current smokers. Smoking was not significantly associated with mucinous OvCa. Associations for all OvCa combined were consistently elevated among former smokers. The proportion of ever smokers who quit within 0-2 years was greater among cases (23%) than controls (7%).

CONCLUSIONS

Cigarette smoking may be associated with serous OvCa among AA, which differs from associations reported among Caucasians. Exposure misclassification or reverse causality may partially explain the absence of increased risk among current smokers and lack of dose-response associations. Better characterization of smoking patterns is needed in this understudied population.

Serum perfluorooctanoic acid (PFOA) concentrations in normal and hyperlipidemic female hamsters dosed orally with ammonium perfluorooctanoate (APFO) for up to 30 days

In epidemiology studies, the presence of perfluorooctanoate (PFOA) in human blood has been associated with higher serum cholesterol concentrations. A possible explanation for these results is that elevated serum cholesterol might reduce clearance of PFOA. In this study, female hamsters, which transport and regulate cholesterol in a manner similar to humans, were fed normal diet or diet supplemented with 0.05% cholesterol and 10% coconut oil (high-fat diet) resulting in hyperlipidemia throughout the study in supplemented animals. Hamsters on either a normal and high-fat diet were given oral doses of 0.1, 1.0, or 10 mg APFO/kg for 30 days. Serum PFOA concentrations evaluated 24 h after 1, 10, 20, and 30 doses of APFO were not altered in hyperlipidemic hamsters compared to those fed normal diet. For a given dose group, serum concentrations of PFOA were highest following the 10 doses (except for the 10 mg/kg group where concentrations were the highest after the first dose) and were lowest after 20 and 30 doses. Under the condition of this study, higher serum lipids did not affect the absorption and clearance of serum PFOA. Serum PFOA concentrations declined over the course of the study despite continued daily dosing with APFO. This does not support the hypothesis that higher serum lipids might increase the retention of PFOA in the body.

Broader health coverage is good for the nation's health: evidence from country level panel data

Progress towards universal health coverage involves providing people with access to needed health services without entailing financial hardship and is often advocated on the grounds that it improves population health. The paper offers econometric evidence on the effects of health coverage on mortality outcomes at the national level. We use a large panel data set of countries, examined by using instrumental variable specifications that explicitly allow for potential reverse causality and unobserved country-specific characteristics. We employ various proxies for the coverage level in a health system. Our results indicate that expanded health coverage, particularly through higher levels of publicly funded health spending, results in lower child and adult mortality, with the beneficial effect on child mortality being larger in poorer countries.