Gamma-glutamyltransferase and disability pension: a cohort study of construction workers in Germany

Associations between Liver Enzymes, Lifestyle Risk Factors and Pre-Existing Medical Conditions in a Population-Based Cross-Sectional Sample

While alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) enzymes are commonly used indicators of liver dysfunction recent studies have suggested that these may also serve as predictive biomarkers in the assessment of extrahepatic morbidity. In order to shed further light on the interactions between serum liver enzyme abnormalities, factors of lifestyle and health status we examined ALT and GGT activities in a population-based sample of 8743 adult individuals (4048 men, 4695 women from the National FINRISK 2002 Study, mean age 48.1 ± 13.1 years) with different levels of alcohol drinking, smoking, physical activity, body weight and the presence or absence of various pre-existing medical conditions. The assessments also included laboratory tests for inflammation, lipid status and fatty liver index (FLI), a proxy for fatty liver. The prevalence of ALT and GGT abnormalities were significantly influenced by alcohol use (ALT: p < 0.0005 for men; GGT: p <0.0005 for both genders), smoking (GGT: p <0.0005 for men, p =0.002 for women), adiposity (p < 0.0005 for all comparisons), physical inactivity (GGT: p <0.0005; ALT: p <0.0005 for men, p <0.05 for women) and coffee consumption (p <0.0005 for GGT in both genders; p <0.001 for ALT in men). The total sum of lifestyle risk factor scores (LRFS) influenced the occurrence of liver enzyme abnormalities in a rather linear manner. Significantly higher LRFS were observed in the subgroups of individuals with pre-existing medical conditions when compared with those having no morbidities (p <0.0005). In logistic regression analyses adjusted for the lifestyle factors, both ALT and GGT associated significantly with fatty liver, diabetes and hypertension. GGT levels also associated with coronary heart disease, angina pectoris, cardiac insufficiency, cerebrovascular disease, asthma and depression. Combinations of abnormal ALT and GGT activities significantly increased the odds for hypertension coinciding with abnormalities in biomarkers of inflammation, lipid status and FLI. The data indicates that ALT and GGT activities readily respond to unfavorable factors of lifestyle associating also with a wide array of pre-existing medical conditions. The data supports close links between both hepatic and extrahepatic morbidities and lifestyle risk factors and may open new insights on a more comprehensive use of liver enzymes in predictive algorithms for assessing mechanistically anchored disease conditions.

Predictive risk markers in alcoholism

The medical disorders of alcoholism rank among the leading public health problems worldwide and the need for predictive and prognostic risk markers for assessing alcohol use disorders (AUD) has been widely acknowledged. Early-phase detection of problem drinking and associated tissue toxicity are important prerequisites for timely initiations of appropriate treatments and improving patient's committing to the objective of reducing drinking. Recent advances in clinical chemistry have provided novel approaches for a specific detection of heavy drinking through assays of unique ethanol metabolites, phosphatidylethanol (PEth) or ethyl glucuronide (EtG). Carbohydrate-deficient transferrin (CDT) measurements can be used to indicate severe alcohol problems. Hazardous drinking frequently manifests as heavy episodic drinking or in combinations with other unfavorable lifestyle factors, such as smoking, physical inactivity, poor diet or adiposity, which aggravate the metabolic consequences of alcohol intake in a supra-additive manner. Such interactions are also reflected in multiple disease outcomes and distinct abnormalities in biomarkers of liver function, inflammation and oxidative stress. Use of predictive biomarkers either alone or as part of specifically designed biological algorithms helps to predict both hepatic and extrahepatic morbidity in individuals with such risk factors. Novel approaches for assessing progression of fibrosis, a major determinant of prognosis in AUD, have also been made available. Predictive algorithms based on the combined use of biomarkers and clinical observations may prove to have a major impact on clinical decisions to detect AUD in early pre-symptomatic stages, stratify patients according to their substantially different disease risks and predict individual responses to treatment.

Determination of Cardiovascular Risk in 56,262 Spanish Construction Workers: Cardiovascular Risk in Construction Workers

OBJECTIVE

To evaluate different cardiovascular risk scales in construction workers.

METHODS

A descriptive, cross-sectional study was carried out in 56,262 Spanish construction workers. Scales of obesity and fatty liver, metabolic syndrome, atherogenic indices, and cardiovascular risk scales, among others, were assessed.

RESULTS

In women, 19.6% were obese, 18.2% hypertensive, 12.6% had metabolic syndrome, 12% were at high risk of non-alcoholic fatty liver disease, and 4.3% were at moderate or high risk on the SCORE scale. In men, 20.1% were obese, 30.1% hypertensive, 17.5% had metabolic syndrome, and 27.6% had high or moderate risk on the SCORE scale.

CONCLUSIONS

Knowing the cardiovascular risk of a large number of construction workers by means of a large number of scales may be of great interest to occupational health professionals, as it may enable them to establish prevention strategies.

γ-Glutamyl Transferase Is Associated with Mortality Outcomes Independently of Fatty Liver

BACKGROUND

High serum enzyme activity levels of γ-glutamyl transferase (GGT) are associated with increased risk of mortality, but whether this is mediated by fatty liver, as a common cause of high GGT levels, is uncertain. Our aim was to test whether GGT levels are associated with all-cause, cancer, and cardiovascular (CVD) mortality, independently of fatty liver.

METHODS

In an occupational cohort (n = 278 419), causes of death (International Statistical Classification of Diseases and Related Health Problems, 10th revision) were recorded over 7 years. Liver function tests and liver fat [measured by ultrasonographic standard criteria or fatty liver index (FLI)] were assessed at baseline. We used Cox proportional hazards models to estimate adjusted hazard ratios (HRs) and 95% CIs of all-cause, cancer, and CVD mortality for GGT quartiles (with lowest GGT quartile as reference).

RESULTS

There were 136, 167, 265, and 342 deaths across increasing GGT quartiles. After adjusting for liver fat (by ultrasound diagnosis) in the fully adjusted model, all-cause and cancer mortality were increased in the highest GGT quartile [HR 1.50 (95% CI 1.15-1.96) and 1.57 (1.05-2.35), respectively]. For CVD mortality, the hazard was attenuated: HR 1.35 (95% CI 0.72-2.56). After adjusting for FLI in the fully adjusted model, HRs for all-cause, cancer, and CVD mortality were 1.46 (0.72-2.56), 2.03 (1.02-4.03), and 1.16 (0.41,3.24), respectively.

CONCLUSIONS

There were similar hazards for all-cause and cancer mortality and attenuated hazards for CVD mortality for people in the highest GGT quartile, adjusting for fatty liver assessed by either ultrasound or FLI.

A novel hypothesis for atherosclerosis as a cholesterol sulfate deficiency syndrome

BACKGROUND

Despite a vast literature, atherosclerosis and the associated ischemia/reperfusion injuries remain today in many ways a mystery. Why do atheromatous plaques make and store a supply of cholesterol and sulfate within the major arteries supplying the heart? Why are treatment programs aimed to suppress certain myocardial infarction risk factors, such as elevated serum homocysteine and inflammation, generally counterproductive?

METHODS

Our methods are based on an extensive search of the literature in atherosclerotic cardiovascular disease as well as in the area of the unique properties of water, the role of biosulfates in the vascular wall, and the role of electromagnetic fields in vascular flow. Our investigation reveals a novel pathology linked to atherosclerosis that better explains the observed facts than the currently held popular view.

RESULTS

We propose a novel theory that atherosclerosis can best be explained as being due to cholesterol sulfate deficiency. Furthermore, atheromatous plaques replenish the supply of cholesterol and sulfate to the microvasculature, by exploiting the inflammatory agent superoxide to derive sulfate from homocysteine and other sulfur sources. We argue that the sulfate anions attached to the glycosaminoglycans in the glycocalyx are essential in maintaining the structured water that is crucial for vascular endothelial health and erythrocyte mobility through capillaries. Sulfate depletion leads to cholesterol accumulation in atheromas, because its transport through water-based media depends on sulfurylation. We show that streaming potential induces nitric oxide (NO) release, and NO derivatives break down the extracellular matrix, redistributing sulfate to the microvasculature. We argue that low (less negative) zeta potential due to insufficient sulfate anions leads to hypertension and thrombosis, because these responses can increase streaming potential and induce nitric-oxide mediated vascular relaxation, promoting oxygen delivery. Our hypothesis is a parsimonious explanation of multiple features of atherosclerotic cardiovascular disease.

CONCLUSIONS

If our interpretation is correct, then it would have a significant impact on how atherosclerosis is treated. We recommend a high intake of sulfur-containing foods as well as an avoidance of exposure to toxicants that may impair sulfate synthesis.

Incident disability in older adults: prediction models based on two British prospective cohort studies

OBJECTIVE

To develop and validate a prediction model for incident locomotor disability after 7 years in older adults.

SETTING

Prospective British cohort studies: British Women's Heart and Health Study (BWHHS) for development and the English Longitudinal Study of Ageing (ELSA) for validation.

SUBJECTS

Community-dwelling older adults.

METHODS

Multivariable logistic regression models after selection of predictors with backward elimination. Model performance was assessed using metrics of discrimination and calibration. Models were internally and externally validated.

RESULTS

Locomotor disability was reported in BWHHS by 861 of 1,786 (48%) women after 7 years. Age, a history of arthritis and low physical activity levels were the most important predictors of locomotor disability. Models using routine measures as predictors had satisfactory calibration and discrimination (c-index 0.73). Addition of 31 blood markers did not increase the predictive performance. External validation in ELSA showed reduced discrimination (c-index 0.65) and an underestimation of disability risks. A web-based calculator for locomotor disability is available (http://www.sealedenvelope.com/trials/bwhhsmodel/).

CONCLUSIONS

We developed and externally validated a prediction model for incident locomotor disability in older adults based on routine measures available to general practitioners, patients and public health workers, and showed an adequate discrimination. Addition of blood markers from major biological pathways did not improve the performance of the model. Further replication in additional data sets may lead to further enhancement of the current model.

The etiology, diagnosis and prevention of liver cirrhosis: part 1 of a series on liver cirrhosis

BACKGROUND

Cirrhosis of the liver is the end stage of chronic liver disease. Among the many liver disorders that can lead to cirrhosis, some progress rapidly (years) and others more slowly (decades). In Germany, cirrhosis is often a consequence of fatty liver disease due to alcoholism or other causes, but can also be caused by hepatitis B and hepatitis C. Cirrhosis is more common in overweight persons and smokers. The underlying causes of cirrhosis determine its rate of progression and are the focus of preventive efforts and treatment. The prevalence of cirrhosis in Germany is rising; it now ranks among the top 20 causes of death in the country.

METHODS

This article is based on a selective review of pertinent literature, including reviews and current guidelines.

RESULTS

Strictly speaking, cirrhosis is a pathological diagnosis; it is, nevertheless, usually diagnosed clinically, by history, physical examination (e.g., cutaneous signs of liver disease), ancillary testing (e.g., ultrasonography, transient elastography) and laboratory analyses (e,g., APRI, which is the quotient of the GOT concentration and the platelet count). There are no laboratory cutoff values for the diagnosis of cirrhosis. Early detection of chronic liver disease, followed by individually tailored, risk-adapted treatment, is the best way to prevent it. Esophagogastroduodenoscopy can be performed early on to assess the risk of variceal bleeding. In most patients, the progression of fibrosis can be averted by early detection and appropriate treatment.

CONCLUSION

Screening for chronic liver disease should include history and physical examination, serum transaminase measurement, upper abdominal ultrasonography, and, in some cases, transient elastography.

Oxidative stress-elevated high gamma glutamyl transferase levels, and aging, intake of tropical food plants, migration and visual disability in Central Africans

AIM

To investigate the independent pathogenic role of high serum gamma-glutamyl transferase (GGT) levels, sociodemographic data, dietary and environmental risk factors for visual disability (VD).

METHODS

This was a case-control study, run in 200 black Congolese patients managed in Saint Joseph Hospital Ophthalmology Division from Kinshasa town. Logistic regression model was used to identify determinants of VD (n=58) among sex, age, cigarette smoking, alcohol abuse, rural-urban migration, education levels, aging ≥60 years, intake of red Beans, Safou fruit and Taro leaves, lipid profile, residence, socioeconomic status, and GGT.

RESULTS

After adjusting for confounding factors, we identified migration (OR=3.7 95% CI: 1.2-11.3; P=0.023), low education level (OR=3.1 95% CI 1.1-8.5; P=0.026), no intake of Safou fruit (OR=34.2 95% CI 11.5-102; P<0.0001), age ≥ 60 years (OR=2.5 95% CI 1.01-6.5; P=0.049), and serum GGT ≥10 U/L (OR=3.6 95% CI 1.3-9.6; P=0.012) as the significant and independent determinants of VD.

CONCLUSION

VD appears as a major public health problem in Central Africa to be prevented or delayed by control of migration, lifestyle changes, antioxidant supplements, appropriate diet, nutrition education, and blocking of oxidative stress.

Gamma-glutamyltransferase, general and cause-specific mortality in 19,000 construction workers followed over 20 years

BACKGROUND & AIMS

Associations of serum gamma-glutamyltransferase levels with a variety of incident diseases and mortality have been suggested. The present study attempted to expand the body of evidence to especially relevant occupational cohorts in which exposure to established γ-GT determinants may greatly differ from the general population.

METHODS

The study was based on occupational health examinations conducted from 1986 to 1992 in 19,090 German male workers from the construction industry, aged 25-64years. Sociodemographics and other health-related information were collected during the exam. Vital status follow-up was conducted through 2008. Associations of baseline γ-GT levels (measurements at 25°C) with all-cause and cause-specific mortality were examined by Kaplan-Meier plotting and multiple adjusted Cox regression models.

RESULTS

A total of 2170 deaths occurred during 303,198 person-years of follow-up. The risk of death due to any cause was 2.5-fold increased in subjects in the highest (⩾39U/L) versus lowest (<11U/L) γ-GT quintile. To varying extents, elevated γ-GT was associated with higher mortality due to cancer, circulatory, respiratory, and digestive causes, as well as accidents/poisoning.

CONCLUSIONS

The findings in this cohort provide evidence for γ-GT being associated with a broad range of causes of death, including less investigated outcomes. Some characteristics of the observed patterns need to be seen in the context of our cohort, featuring particularly high γ-GT levels.

Smoking and γ-glutamyltransferase: opposite interactions with alcohol consumption and body mass index

Background

Smoking has recently been suggested to synergistically interact with alcohol intake as a determinant of serum gamma-glutamyltransferase (γ-GT), an emergent powerful predictor of disease and mortality. This study investigated whether this also applies to higher smoking and alcohol exposure ranges and to body mass index (BMI), which likewise is strongly associated with γ-GT.

Methodology/Principal Findings

Analyses were based on occupational health examinations of more than 15,000 German male workers aged 16–64 years, predominantly from the construction industry. Sociodemographics and other health-related information were collected during the exam. Joint associations of smoking and alcohol consumption or BMI with elevated or log-transformed γ-GT were examined by tabulation and multiple adjusted regression models. Cigarette smoking exerted no effect on γ-GT in teetotalers, but there was a statistically significant effect of smoking among participants with higher alcohol consumption intensity, odds of elevated γ-GT being increased by 24% and 27% per additional 10 cigarettes smoked per day in subjects drinking 61–90 and >90 gram alcohol per day, respectively (P for interaction = 0.039). The interaction was opposite for BMI, where no association was seen in obese subjects, whereas odds of elevated γ-GT were increased by 24% per 10 cigarettes below 25 kg/m² (P for interaction = 0.040). This novel interaction was replicable in an independent cohort.

Conclusion

The evidence for opposite interactions of smoking with alcohol and BMI as determinants of serum γ-GT suggests that different physiological pathways are responsible for the associations between these factors.