Impact of cigarette smoking on the relationship between body mass index and insulin: Longitudinal observation from the Bogalusa Heart Study

The impact of serum acid, arterial stiffness, and hypertension as a mediating factor: A cohort study

BACKGROUND

Serum uric acid (SUA) has been associated with arterial stiffness. However, previous studies were limited to contradicting cross-sectional studies. This study aimed to examine the longitudinal association between SUA and the progression of arterial stiffness and the potential mechanisms.

METHODS

Based on the Kailuan study, arterial stiffness progression was assessed by the annual growth rate of repeatedly measured brachial-ankle pulse wave velocity (baPWV). Generalized linear regression models were used to estimate the association of SUA with baseline arterial stiffness (n = 37,659) and arterial stiffness progression (n = 16,506), and Cox regressions were used to investigate the risk of incident arterial stiffness (n = 13,843). Mediation analysis was used to explore the potential mediators of the associations.

RESULTS

Per standard deviation increase in SUA was associated with an 11.89 cm/s increment (95% confidence interval [CI], 8.60-15.17) in baseline baPWV and a 2.67 cm/s/yr increment in the annual growth rate of baPWV. During the 5.77-year follow-up, there were 1953 cases of incident arterial stiffness. Participants in the highest quartile of SUA had a 39% higher risk of arterial stiffness (HR, 1.39; 95% CI, 1.21-1.60), as compared with those in the lowest quartile of SUA. Furthermore, the observed associations were more pronounced in women than in men (Pint<0.05). The pathological pathway from high SUA to arterial stiffness was mainly mediated through hypertension (mediated proportion: 24.74%).

CONCLUSIONS

Our study indicates that SUA was positively associated with the risk of arterial stiffness and its progression, especially in women. The association was mainly mediated through hypertension.

Association of serum uric acid to lymphocyte ratio, a novel inflammatory biomarker, with risk of stroke: A prospective cohort study

MAIN PROBLEM

Inflammation plays an important role in the pathological progress associated with stroke. Serum uric acid (SUA) to lymphocyte ratio (ULR), a novel inflammatory biomarker, has been considered as a better risk stratification tool of adverse outcomes than SUA or lymphocyte alone. This study aimed to investigate whether ULR produced more predictive value for stroke and explore the potential mediators of the associations.

METHODS

This study enrolled 93,023 Chinese participants without stroke and myocardial infarction at baseline. Cox proportional hazard models were used to analyze the associations of ULR with stroke and subtypes. Mediation analyses were conducted to explore potential mediators of the associations.

RESULTS

During a median follow-up of 13.00 years, 6081 cases of incident stroke occurred, including 5048 cases of ischemic stroke (IS) and 900 cases of hemorrhagic stroke (HS). After adjustment for confounders, the Q4 group was associated with a higher risk of HS (HR, 1.25; 95% CI, 1.03-1.50), but not with total stroke (HR, 1.07; 95% CI, 1.03-1.13) or IS (HR, 1.04; 95% CI, 0.97-1.12). No significant associations were found between SUA or lymphocyte and any stroke. ULR outperformed SUA or lymphocytes alone in predicting stroke. Additionally, the significant association between ULR and HS was partially mediated by systolic blood pressure (20.32%), diastolic blood pressure (11.18%) and estimated glomerular filtration rate (9.19%).

CONCLUSIONS

ULR was significantly associated with the risk of HS, but not with IS. Systolic blood pressure, diastolic blood pressure and estimated glomerular filtration rate were potential mediators for the association.

Prevalence of cardiovascular risk factors in middle-aged Lithuanian women in different body mass index and waist circumference groups

BACKGROUND AND AIMS

The aim of this study was to evaluate the prevalence of cardiovascular risk factors in middle-aged Lithuanian women in different body mass index and waist circumference groups.

METHODS AND RESULTS

Data selected from the Lithuanian High Cardiovascular Risk (LitHiR) primary prevention program between 2009 and 2016. This community-based cross-sectional study comprised 53,961 women aged 50-64 years old. We compared the prevalence of arterial hypertension, dyslipidaemia, diabetes mellitus, smoking, and metabolic syndrome in different body mass index (BMI) and waist circumference (WC) groups. The most prevalent cardiometabolic risk factor was dyslipidaemia (91.71%, n = 49,488). The prevalence of arterial hypertension, dyslipidaemia, diabetes mellitus, and metabolic syndrome was greater in those with higher-than-normal BMI and WC. Smoking was the most prevalent in women with low BMI and normal WC (24.00% and 13.17% respectively).

CONCLUSION

The analysis showed that all risk factors, except smoking, were significantly more prevalent in women with higher-than-normal BMI and with increased WC or abdominal obesity. The prevalence of dyslipidaemia was surprisingly high in all BMI and WC groups. Obesity measured by WC was more strongly associated with an adverse metabolic profile.

Effect of Club cell secretory proteins on the association of tobacco smoke and PAH co-exposure with lung function decline: A longitudinal observation of Chinese coke oven workers

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAH) and tobacco smoke is associated with epithelial damage and reduced lung function. Club cell secretory protein (CC16) is a known biomarker for lung epithelial cells. However, the potential relationships between PAH and tobacco smoke exposure, CC16 levels, and reduced lung function remain unclear.

OBJECTIVES

This longitudinal study aimed to explore the potential role of CC16 in the association of tobacco smoke and PAH co-exposure with lung function.

METHODS

We enrolled 313 workers from a coking plant in China in 2014 and followed them up in 2019. The concentrations of PAH and nicotine metabolites in urine were determined using high-performance liquid chromatography (HPLC) with a fluorescence detector and HPLC-tandem mass spectrometry, respectively. The plasma CC16 concentration was determined using an enzyme-linked immunosorbent assay.

RESULTS

An analysis of the generalized estimating equation showed that each 1-unit increase in log-transformation of the last tertile of trans-3'-hydroxycotinine (3HC) was associated with a 3.30 ng/ml decrease in CC16. Restricted cubic spline analysis revealed a significant nonlinear dose-effect association between cotinine (COT) and CC16 (P_nonlinear = 0.018). In the low- CC16 subgroup, we found a significant association between total nicotine metabolites and forced vital capacity (FVC%) (β: 1.45, 95% CI: 2.87, -0.03), and the associations of nicotine (NIC), COT, and 3HC with FVC% were all of marginal significance. High levels of total hydroxyl polycyclic aromatic hydrocarbons (ΣOH-PAH) and NIC in the urine had an interactive effect on the decline of CC16 (P < 0.05). Cross-lagged panel analysis indicated that the decrease in CC16 preceded the decrease in FVC%. CC16 mediated the association between elevated nicotine metabolites and decreased FVC% in the low- CC16 subgroup.

CONCLUSIONS

CC16 plays an essential role in the association of PAH and tobacco smoke exposure with reduced lung function. Coke oven workers with low plasma CC16 levels are more likely to experience decreased lung function after tobacco smoke exposure.

Serial Mediation Roles of Perceived Stress and Depressive Symptoms in the Association Between Sleep Quality and Life Satisfaction Among Middle-Aged American Adults

In this study, we used data from the second wave of Midlife in the United States (MIDUS) Study, MIDUS Biomarkers and MIDUS 3. We applied the serial mediation model to explore the serial mediating effects of perceived stress and depressive symptoms on the relationship between sleep quality and life satisfaction. A total of 945 participants were included in our study. The total indirect effect of sleep quality on life satisfaction through perceived stress, depressive symptoms and the combination of perceived stress and depressive symptoms accounted for within the overall model was 45.5%. At the intervention level, programs designed to improve the level of life satisfaction among adults should focus on perceived stress and depressive symptoms. The prevention of perceived stress and depression contributes to improving life satisfaction and wellbeing. The serial mediation results should be confirmed by further longitudinal study.

An Analysis of the Links between Smoking and BMI in Adolescents: A Moving Average Approach to Establishing the Statistical Relationship between Quantitative and Dichotomous Variables

The aim of this study was to determine the effect of smoking on BMI in male adolescents and explore the relationship between smoking status and diet. Methods: A cross-sectional epidemiological study into the health and diet of adolescents was carried out based on a representative sample of 375 vocational school male students aged 16–17 in the city of Chelyabinsk (Russian Federation). The students and their parents filled out verified questionnaires on their socioeconomic status, diet, and smoking status. Students’ height and body weight were measured. A comparative analysis of diets was performed between groups of smokers and non-smokers (149 and 226 individuals, respectively), and the relationship between smoking, body mass index, and actual diet was estimated. The methods used included descriptive statistics, Student’s t-test, Mann–Whitney U test, comparison of proportions, and moving average. Results: Non-smoking adolescent boys tended to have excess body mass compared with smokers (19.0% and 12.1%, respectively). Smokers (adolescent boys) consumed less meat, cereals, beans, and cheeses and more sweet beverages, added sugar, coffee, and alcohol. The bulk of the smokers’ diet was composed of carbohydrates (p = 0.026) and, to a lesser extent, proteins (p = 0.006). Conclusions: Significant differences were discovered in the diet between smokers and non-smokers (among adolescent boys), and smoking was associated with several indicators of unhealthy diet patterns. This is an important conclusion for developing a future program that could additionally protect at-risk groups of adolescents.

Interaction of polycyclic aromatic hydrocarbon exposure and high-fasting plasma glucose on lung function decline in coke oven workers: a cross-lagged panel analysis

Individuals with abnormal fasting plasma glucose (FPG) may be more susceptible to lung diseases associated with environmental pollutants. A cross-sectional survey of 629 workers in 2017 and a panel study of 304 workers from 2014 to 2019 were performed in China. The results showed that elevated total hydroxylated polycyclic aromatic hydrocarbon (ΣOH-PAH) concentration was associated with lower the percentage of predicted forced vital capacity (FVC%) among high-FPG workers (β for the cross-sectional analysis: -1.78%, 95%CI: -2.92%, -0.64%; β for the panel study: -1.10%, 95%CI: -2.19%, -0.02%). The absolute value of the cross-lagged path coefficient from FPG to FVC% (β₂ = -0.096) was significantly greater than that from FVC% to FPG (β₁ = 0.037). Our results suggest that FPG abnormalities may precede the lung function decline induced by PAH exposure and that high-FPG and high ΣOH-PAH levels have an interactive effect on lung function decline.

Metabolic Factors Mediate the Association Between Serum Uric Acid to Serum Creatinine Ratio and Cardiovascular Disease

Background

The serum uric acid/serum creatinine ratio (SUA/SCr), which represents renal function‐normalized SUA, is associated with diverse adverse outcomes. The aim of this study was to investigate the association between SUA/SCr and cardiovascular disease (CVD), and determine whether and to what extent this association is mediated by cardiometabolic factors.

Methods and Results

This prospective study enrolled 96 378 participants from the Kailuan study without stroke and myocardial infarction at baseline (2006). Cox proportional hazard models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). Mediation analyses were conducted to separately explore the mediating effects of cardiometabolic factors on the association between SUA/SCr and CVD. During median follow up of 11.01 years, 6315 (6.55%) individuals developed incident CVD. After adjustment for potential confounders, the highest quartile of SUA/SCr was associated with the highest risk of CVD (HR, 1.15; 95% CI, 1.07–1.23), stroke (HR, 1.16; 95% CI, 1.07–1.26), ischemic stroke (HR, 1.12; 95% CI, 1.02–1.22), and hemorrhagic stroke (HR, 1.36; 95% CI, 1.11–1.65), but not with myocardial infarction (HR, 1.07; 95% CI, 0.92–1.25). The association was consistent across different degrees of kidney function and glucose tolerance statuses. Additionally, the association between high SUA/SCr and CVD was partially mediated by triglycerides (30.74%), body mass index (BMI) (19.52%), total cholesterol (15.06%), hs‐CRP (high‐sensitivity C‐reactive protein) (13.06%), diastolic blood pressure (11.75%), and blood glucose (−16.38%).

Conclusions

SUA/SCr and CVD were positively associated. Furthermore, this association was partially mediated through blood lipids, BMI, blood pressure, hs‐CRP, and blood glucose.

Triglyceride-Glucose Index Is Not Associated With Lung Cancer Risk: A Prospective Cohort Study in the UK Biobank

BACKGROUND

The triglyceride-glucose (TyG) index is a practical substitute measure for insulin resistance (IR). The relationship between IR and lung cancer has been examined in previous studies; however, the findings have been controversial. In addition, previous studies had small sample sizes. Thus, we systematically examined the association between IR and lung cancer risk based on the UK Biobank with IR measured by the TyG index and further examined the interactions and joint effects for lung cancer.

METHODS

A total of 324,334 individuals free from any type of cancer at recruitment from the UK Biobank prospective cohort were included. The participants were predominantly between 40 and 70 years old. After adjusting for relevant confounders, multivariable Cox regression models were constructed to examine the relationship between the TyG index and the risk of lung cancer. We also checked the interactions and joint effects using a polygenic risk score (PRS) for lung cancer.

RESULTS

During a median follow-up of 9 years, 1,593 individuals were diagnosed with lung cancer. No association was found between the TyG index and lung cancer risk after multivariate Cox regression analysis adjusted for risk factors (hazard ratio: 0.91; 95% confidence interval: 0.64-1.18). No interaction or joint effects for genetic risk and the TyG index were observed.

CONCLUSION

The TyG index was not associated with the risk of lung cancer. Our results provide limited evidence that IR is not correlated with the risk of lung cancer.

Mediation analysis methods used in observational research: a scoping review and recommendations

Background

Mediation analysis methodology underwent many advancements throughout the years, with the most recent and important advancement being the development of causal mediation analysis based on the counterfactual framework. However, a previous review showed that for experimental studies the uptake of causal mediation analysis remains low. The aim of this paper is to review the methodological characteristics of mediation analyses performed in observational epidemiologic studies published between 2015 and 2019 and to provide recommendations for the application of mediation analysis in future studies.

Methods

We searched the MEDLINE and EMBASE databases for observational epidemiologic studies published between 2015 and 2019 in which mediation analysis was applied as one of the primary analysis methods. Information was extracted on the characteristics of the mediation model and the applied mediation analysis method.

Results

We included 174 studies, most of which applied traditional mediation analysis methods (n = 123, 70.7%). Causal mediation analysis was not often used to analyze more complicated mediation models, such as multiple mediator models. Most studies adjusted their analyses for measured confounders, but did not perform sensitivity analyses for unmeasured confounders and did not assess the presence of an exposure-mediator interaction.

Conclusions

To ensure a causal interpretation of the effect estimates in the mediation model, we recommend that researchers use causal mediation analysis and assess the plausibility of the causal assumptions. The uptake of causal mediation analysis can be enhanced through tutorial papers that demonstrate the application of causal mediation analysis, and through the development of software packages that facilitate the causal mediation analysis of relatively complicated mediation models.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01426-3.

Bidirectional temporal relationship between obesity and hyperinsulinemia: longitudinal observation from a Chinese cohort

INTRODUCTION

Although obesity and hyperinsulinemia are closely intercorrelated, their temporal sequence is still uncertain. This study aims to investigate the temporal relationship patterns between obesity measures and hyperinsulinemia in Chinese adults.

RESEARCH DESIGN AND METHODS

The longitudinal cohort consisted of 2493 participants (860 males and 1633 female, mean age 56.71 years at follow-up) for whom measurements of obesity and hyperinsulinemia measures were collected twice between 2011 and 2014, with an average follow-up time of 3 years. Cross-lagged panel analysis was used to examine the temporal relationship between obesity measures (body mass index (BMI); waist circumference (WC); hip circumference (HC); waist-to-hip ratio (WHR)) and hyperinsulinemia (insulin, homeostasis model assessment of insulin resistance (HOMA-IR), or homeostasis model assessment of beta cell function (HOMA-%β)).

RESULTS

After the adjustment of age, sex, smoking, drinking and follow-up years, in the BMI-insulin model, the path coefficient (β₂=0.229; p<0.001) of baseline BMI to follow-up insulin was significantly greater than the path coefficient (β₁=0.073; p<0.001) of baseline insulin to follow-up BMI (p<0.001 for β₂>β₁). In the WHR-insulin model, the path coefficient (β₁=0.152; p<0.001) of baseline insulin to follow-up WHR was significantly greater than the path coefficient (β₂=0.077; p<0.001) of baseline WHR to follow-up insulin (p=0.007 for β₁>β₂). In the WC/HC-insulin model, the path coefficients of baseline insulin to follow-up WC or HC (β_1s) were also greater than the path coefficients of baseline WC or HC to follow-up insulin (β_2s), but the difference between β_1s and β_2s were not significant. The similar temporal patterns were founded between obesity measures with HOMA-IR or HOMA-%β.

CONCLUSIONS

These findings indicate that there is a bidirectional relationship between obesity and hyperinsulinemia, and abdominal obesity measures are more sensitive to hyperinsulinemia measures than BMI.

Reciprocal influences of tobacco use on illicit opioid and alcohol use during the first six-months of specialist addiction treatment

BACKGROUND

This is the first national study of lagged reciprocal associations between tobacco smoking frequency and change in illicit opioid or alcohol use frequency within six-months of treatment.

METHODS

All adults admitted to publicly-funded specialist addiction treatment in England in 2018/19 and enrolled for at least six months for either opioid use disorder (OUD; n = 22,046; 82.4 % of those eligible) or alcohol use disorder (AUD; n = 15,251; 78.8 % of those eligible). Two cross-lagged panel models estimated, separately for OUD and AUD patients, the relationships between smoking at admission and change in main drug over six months, and between main drug use at admission and change in smoking over six months.

RESULTS

Within the OUD cohort, illicit opioid use frequency reduced from 17.7 days to 8.0 days and smoking tobacco remained at 18.8 days. After controlling for available covariates, higher smoking frequency at admission was associated with a relative increase in illicit opioid use at six-months (0.02 days [95 % CI 0.00-0.03]). Within the AUD cohort, alcohol use frequency reduced from 21.2 days to 14.4 days while smoking tobacco reduced from 12.6 days to 11.5 days. Higher smoking frequency at admission was associated with a relative increase in alcohol use at six-months (0.03 days [95 % CI 0.02-0.04]) and higher alcohol use frequency at admission was associated with a relative increase in smoking at six-months (0.04 [95 % CI 0.02-0.06]), controlling for available covariates.

CONCLUSIONS

Higher smoking frequency at admission is associated with higher illicit opioid and alcohol use frequency after six-months of specialist addiction treatment.

Effects of smoking on bariatric surgery postoperative weight loss and patient satisfaction

BACKGROUND

While general population studies have demonstrated a relationship between cigarette smoking and weight loss, this association is not well established among the bariatric patient population. Given that bariatric patients are inherently weight-concerned, understanding the effects of smoking on postoperative weight loss is essential. We examined the association of preoperative smoking, postoperative smoking and changes in smoking status with weight loss after bariatric surgery. In addition, we examined the association of changes in smoking status with subjective indices of patient satisfaction while controlling for weight loss.

METHODS

Retrospective chart review of patients who underwent Sleeve Gastrectomy or Roux-en-Y Gastric Bypass for weight loss at a single institution between August 2000 and November 2017. Additional follow up was obtained by telephone survey. Statistical analysis utilized multivariate logistical regressions.

RESULTS

Our study included 512 patients. Majority were female (n = 390, 76.2%) and underwent laparoscopic Roux-en-Y gastric bypass (n = 362, 70.7%). Average age was 46.8 years and average follow up was 6.99 years. Preoperative, postoperative and changes in smoking status were not significantly associated with weight loss. Former smokers were significantly more likely to report postoperative satisfaction with self-overall OR 10.62 (p < 0.01), satisfaction with postoperative outcomes OR 4.18 (p = 0.02), and improvement in quality of life OR 4.05 (p = 0.04) compared to continued smokers independent of weight loss. No difference in rates of satisfaction were found between former smokers and never smokers. Smoking cessation and weight loss were independently predictive of positive responses to these satisfaction indices.

CONCLUSIONS

We found no association between preoperative smoking, postoperative smoking or changes in smoking status with postoperative weight loss. Smoking cessation was associated with patient satisfaction and improvement in quality of life compared to continued smokers. Smoking cessation and postoperative weight loss were independently predictive of increased patient satisfaction.

Nicotine triggers islet β cell senescence to facilitate the progression of type 2 diabetes

Cigarette smoking is a well-recognized risk factor for type 2 diabetes (T2DM), and may result in islet β cell damage and impaired insulin secretion. However, the underlying mechanisms remain largely elusive. In the present study, we demonstrated that nicotine induced premature senescence of pancreatic β cells in vitro and in vivo. The senescence-associated β-galactosidase (SA-β-Gal) assay showed that nicotine exposure induced apparent senescence phenotype of β-TC-6 cells at an initiating dose of 100 μM and starting from 12 h. In addition, 100 and 500 μM of nicotine exposure altered the expression of senescence marker proteins, such as p16, p19 and p21. Furthermore, we uncovered that the levels of intracellular Ca²⁺ and reactive oxygen species (ROS) were significantly elevated in β-TC-6 cells following exposure to 100 and 500 μM nicotine, while calcium channel blocker can reverse this effect. Furthermore, the senescence-inducing phenotype was confirmed in rat insulinoma INS-1 cells at a similar dose range, whereas blockade of nAChRs, calcium and ROS led to apparent impairment of senescence. Finally, we found that administration with 100 and 200 μg/mL nicotine in drinking water for 28 days significantly exacerbated aberrant glucose homeostasis in a mouse model of fat-induced T2DM. Of great intrigue, pancreatic β cells exhibited significantly enhanced senescence following nicotine administration. Taken together, this study suggests that premature senescence plays a pivotal role in nicotine-triggered β cell destruction and glucose intolerance, providing a theoretical basis for targeted prevention and treatment of smoking-induced T2DM.

Mediation of the effect of serum uric acid on the risk of developing hypertension: a population-based cohort study

Background

Serum uric acid (SUA) had been associated with incident hypertension, but it is uncertain whether and to what extent the effect of SUA is mediated by other metabolic factors.

Methods

Data from the China Health and Retirement Longitudinal Study (CHARLS) during 2011 to 2015 was employed for this study. A total of 7639 participants aged between 35 and 96 years without hypertension was included. Cox proportional hazards model was used to investigate the association between elevated SUA and hypertension. A mediation model was used to separately explore mediating effects (MEs) of metabolic factors on the association between SUA and incident hypertension.

Results

During a median 4.0 years of follow-up, 2348 individuals were diagnosed with hypertension. After adjustment for metabolic confounders, participants with the highest SUA quartile had a hazard ratio of 1.16 (1.02–1.33) compared with the lowest category for incident hypertension. The association between SUA and incident hypertension were partially mediated by waist circumference (WC; ME = 0.034), body mass index (BMI; ME = 0.016), triglycerides (TG; ME = 0.024), total cholesterol (TC; ME = 0.009), high density lipoprotein cholesterol (HDL-C; ME = 0.009), fasting plasma glucose (FPG; ME = 0.005), and glycated hemoglobin (HbA1c; ME = − 0.002). Additionally, proportional mediation was 32.7% by WC and 15.4% by BMI for obesity indicators; 23.1% by TG, 8.7% by TC, and 8.7% by HDL-C for blood lipid; and 4.8% by FPG and − 1.9% by HbA1c for blood glucose.

Conclusions

The positive association between elevated SUA concentration and hypertension was reconfirmed in a Chinese population. Obesity indicators, blood lipids, and blood glucose may play important mediating roles in the pathways.