Secondhand Smoking and Obesity Among Nonsmoking Adolescents Aged 12-15 Years From 38 Low- and Middle-Income Countries

Smoking as a causative factor in chronic kidney disease: a two-sample Mendelian randomization study

Smoking is widely acknowledged for its harmful effects on multiple organs. However, its specific causal relationship with chronic kidney disease (CKD) remains uncertain. This study applied bivariate causal analysis and two-sample Mendelian randomization (MR) methods to examine the association between various smoking behaviors - initiation, cessation, age at initiation, cigarettes smoked per day, and lifetime smoking - and CKD, using genome-wide data. The inverse variance weighted (IVW) method was the primary analytical tool, supported by sensitivity analyses, pleiotropy assessments, and mediation analyses. External validation was conducted using independent datasets. The results revealed positive associations between CKD and smoking initiation (Pivw = 1.8 × 10-2, OR = 1.192), earlier age at initiation (Pivw = 2.3 × 10-3, OR = 1.481), cigarettes smoked per day (Pivw = 8.8 × 10-3, OR = 1.216), and lifetime smoking (Pivw = 2.3 × 10-7, OR = 2.445). In contrast, smoking cessation demonstrated a protective effect against CKD (Pivw = 4.0 × 10-12, OR = 0.791). External validation results aligned with the primary findings, and the absence of significant heterogeneity confirmed the robustness of the MR analysis. Additionally, the effect of smoking on CKD was mediated by factors such as body mass index, cardiovascular disease, hypertension, and type 2 diabetes. These findings identify smoking as a contributing factor to CKD and suggest that reducing smoking prevalence could significantly lower the incidence of CKD in the population.

Temporal changes in smoking prevalence among adolescents across 23 countries

AIM

This study aimed to investigate temporal changes in smoking prevalence among adolescents aged 13-15 across 23 countries and to assess individual and country-level factors influencing smoking behaviour.

METHODS

This study used data from 168 286 young adolescents aged 13-15 years obtained from the Global School-based Student Health, 2003-2021. Linear regression models and meta-analyses were conducted to analyse the changes in current smoking prevalence among young adolescents.

RESULTS

Among the 23 countries, smoking prevalence decreased in six countries, including Argentina, Fiji, Jamaica, Samoa, Tonga and Uruguay, while it increased in four countries, namely Guyana, Morocco, Thailand and Vanuatu. The prevalence of smoking was higher among male adolescents at 15.5% (95% CI 13.8%-17.2%) compared to females at 8.0% (95% CI 6.7%-9.3%). Adolescents exposed to secondhand smoke had a prevalence of 16.3% (95% CI 14.5%-18.2%), significantly higher than 4.2% (95% CI 3.7-4.6) in those not exposed. Smoking prevalence was 16.5% (95% CI 14.8%-18.2%) among those with smoking parents or guardians, compared to 8.1% (95% CI 7.1%-9.1%) among those without.

CONCLUSION

The findings highlight the need for tailored tobacco control measures to reduce adolescent smoking globally. Strengthening policy enforcement and addressing social determinants of smoking are critical to achieving further reductions.

Parental smoking is associated with adolescent loneliness: evidence from 71 low- and middle-income countries

Introduction

The association between parental smoking and adolescent mental health is not well understood. We aimed to examine the association between parental smoking and adolescent loneliness using global data collected from the Global School-based Student Health Survey (GSHS) between 2009 and 2019.

Methods

A total of 187,552 adolescents aged 12-15 years in 71 low- and middle-income countries (LMIC) from the GSHS with cross-sectional design were included in this study. Loneliness was defined as feeling lonely sometimes or more frequently in the past 12 months. Parental smoking, reported by the adolescent, was defined as the use of any form of tobacco by the father and/or mother. Logistic regression models were used to examine the odds ratio (OR) of adolescent loneliness according to parental smoking status.

Results

Compared with neither parent smoking, parental smoking was associated with adolescent loneliness (father only: OR = 1.18, 95% CI = 1.10-1.26; mother only: OR = 1.39, 95% CI = 1.15-1.67; both: OR = 1.65, 95% CI = 1.41-1.93) after adjustment for potential covariates. Subgroup analyses stratified by sex, age, and WHO region showed similar results (except not in the African and Western Pacific regions).

Discussion

Parental smoking is associated with loneliness in adolescents from LMIC. Our finding expands the well-known physical damage of parental smoking in adolescents to the psychological damage. Strict policies and strategies should be established to encourage smoking cessation for parents who are current smokers.

The causal relationship of cigarette smoking to metabolic disease risk and the possible mediating role of gut microbiota

BACKGROUND

Cigarette smoking is a leading cause of preventable death worldwide, with its associated diseases and conditions. Emerging evidence suggests that cigarette smoking contributes to a range of pathological metabolic injuries, including diabetes and nonalcoholic fatty liver disease (NAFLD). The impact of gut microbiota on metabolic health and diseases has been observed, but the causality remains uncertain.

OBJECTIVE

To confirm the causal relationship between cigarette smoking and metabolic diseases, and to investigate the possible mediating effect of gut microbiota on these connections.

METHODS

The relationships among cigarette smoking, metabolic diseases, and the gut microbiome were analyzed by Univariate Mendelian randomization (UVMR). Furthermore, to mitigate the impact of confounding factors, adjusted models were conducted via the multivariate Mendelian randomization (MVMR) method, aiming to improve the accuracy of prediction. Ultimately, the study evaluated the effect of the intermediary factor, gut microbiome, on the relationship between cigarette smoke and metabolic diseases.

RESULTS

The phenomenon that a causal relationship between cigarette smoke (249752 individuals) and gut microbiota (7738 individuals), diabetes (406831 individuals), NAFLD (377998 individuals), hypercholesterolaemia (463010 individuals), and obesity (463010 individuals) was observed using UVMR. In the MVMR model, the genetic connection between cigarette smoking, gut microbiota, and type 2 diabetes remained significant. Of note, paraprevotella_clara served an important mediating role in the type 2 diabetes associated with cigarette smoke.

CONCLUSION

This work offered genetic evidence linking cigarette smoke to metabolic diseases, suggesting that the gut microbiota, particularly paraprevotella_clara, might be a crucial mediator in the development of type 2 diabetes caused by cigarette smoke. Our future studies should consider conducting other ethnic groups MR analyses, particularly with larger sample sizes. Still, more in vivo and in vitro work should be carried out to validate the precise effect and molecular mechanisms of the gut microbiome.

Secondhand Smoke Exposure and Its Impact on Pediatric Lung Function, Aerobic Fitness, and Body Mass: Evidence from a Cross-Sectional Study

BACKGROUND

Several studies have documented the detrimental impacts of secondhand smoke (SHS) exposure to a range of pediatric respiratory conditions, including asthma, bronchitis, and reduced lung function. The aim of the study was to investigate the influence of SHS exposure on lung function, physical fitness, and body mass index (BMI) in children aged 10 to 14 years.

METHODS

This cross-sectional study included children aged 10 to 14 years at the Elementary School "Trilj" in Trilj, Croatia. Data on SHS exposure were collected using a questionnaire. Antropometric and spirometry measurements were performed. Physical fitness was assessed using the shuttle run (BEEP) test.

RESULTS

This study included 157 children, 89 (56.69%) boys and 68 (43.31%) girls. Children exposed to every day SHS in households had significantly lower values of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, peak expiratory flow (PEF) (p < 0.001) and higher z-score BMI levels (p = 0.018) in comparison to unexposed children. Logistic regression showed that children unexposed to SHS had higher odds for better results in the BEEP test (OR 62.45, 95% CI 21.26-179.24, p < 0.001). Children with poorer physical fitness, expressed by lower BEEP score levels, had significantly lower FVC, FEV1, FEV1/FVC, and PEF (p < 0.001).

CONCLUSIONS

Every day SHS exposure in children was associated with poorer lung function, higher BMI, and poorer physical fitness.

The association between obesity and glaucoma in older adults: evidence from the China Health and Retirement Longitudinal Study

OBJECTIVES

This study evaluated the association between obesity and glaucoma in middle-aged and older people. A population-based retrospective cohort study was conducted using data from the China Health and Retirement Longitudinal Study.

METHODS

Glaucoma was assessed via self-reports. Multivariate logistic regression analysis and a Cox proportional hazards model were used to assess the relationship between obesity and glaucoma risk.

RESULTS

Older males living in urban areas who were single, smokers, and non-drinkers were found to have a significantly higher incidence of glaucoma (all p<0.05). Diabetes, hypertension, and kidney disease were also associated with higher glaucoma risk, while dyslipidemia was associated with lower risk (all p<0.05). After the model was adjusted for demographic, socioeconomic, and health-related variables, obesity was significantly associated with a 10.2% decrease in glaucoma risk according to the Cox proportional hazards model (hazard ratio, 0.90; 95% confidence interval [CI], 0.83 to 0.97) and an 11.8% risk reduction in the multivariate logistic regression analysis (odds ratio, 0.88; 95% CI, 0.80 to 0.97). A further subgroup analysis showed that obesity was associated with a reduced risk of glaucoma in people living in rural areas, in smokers, and in those with kidney disease (all p<0.05). Obesity also reduced glaucoma risk in people with diabetes, hypertension, or dyslipidemia more than in healthy controls (all p<0.05).

CONCLUSIONS

This cohort study suggests that obesity was associated with a reduced risk of glaucoma, especially in rural residents, smokers, and people with kidney disease. Obesity exerted a stronger protective effect in people with diabetes, hypertension, or dyslipidemia than in healthy people.

Secondhand smoke exposure among never-smoking adolescents in Wuhan, China

Without smoke-free legislation in Wuhan, China, we investigated secondhand smoke (SHS) exposure at home, school, and public places for never-smoking school-going adolescents in 2019. A cross-sectional study was carried out within the Global Youth Tobacco Survey (GYTS) framework. Weighted univariate, bivariate and multivariable analyses were conducted. The prevalence of SHS exposure among never-smoking adolescents at home, school and public places was 25.7%, 31.9% and 48.9%, respectively. Multivariable logistic regression analysis showed that parents smoking, peers smoking and observing teachers smoking in school were all significantly related to a higher probability of SHS exposure at home, school, and public places. Never-smoking adolescents who had smoking parents had 14 times (adjusted odds ratio [aOR], 14.00; 95% confidence interval [CI], 11.37–17.24) higher odds of SHS exposure at home; Never-smoking adolescents who observed teachers smoking in school had about 10 (aOR = 9.76; 95% CI = 7.13–13.36) and four times (aOR = 3.55; 95% CI = 2.77–4.55) higher odds of SHS exposure in school and public places, respectively. Adopting comprehensive smoke-free legislation in public places and smoke-free home rules and implementing and supervising smoke-free school policies may further reduce SHS exposure among adolescents.

Linking Global Youth Tobacco Survey (GYTS) data to the WHO Framework Convention on Tobacco Control (FCTC): The case for Tunisia

INTRODUCTION

The World Health Organization (WHO) had launched the Framework convention on Tobacco Control (FCTC) in 2003 in order to curve the epidemic of tobacco use worldwide. Since most smokers begin to smoke before the age of 18 years, Global Youth Tobacco Survey (GYTS) has been developed in order to monitor tobacco smoking among adolescents. Our aim was to assess smoking among Tunisian youth using GYTS 2017 data.

METHODS

GYTS is cross-sectional, two cluster school-based survey to produce a representative sample of students aged 13-15 years. It was conducted in 2017 in 67 secondary schools in Tunisia. The investigation tool was an anonymously answered questionnaire, which contained core questions about six majors tobacco related topics.

RESULTS

Lifetime cigarettes and waterpipe prevalence were 7.8% (14.4% of boys, 1.6% of girls, p<0.001) and 7.2% (13% of boys, 2.8% of girls, p<0.001), respectively. Among cigarette smokers, 62.5% were able to buy their own cigarettes. Overall, 23.5% of cigarette smokers and 41.5% of waterpipe smokers were not able to buy their products because of their age. Sixty percent of smokers wanted to quit and 56.4% had already tried to stop. Half of the respondents were exposed to SHS in their homes and 62.1% in indoor public places.

CONCLUSIONS

In Tunisia, tobacco prevalence among youth is high. Youth have free access to tobacco products and smoke-free regulations are only partially respected.