Quantifying the association of low-intensity and late initiation of tobacco smoking with total and cause-specific mortality in Asia

Lung Cancer Risk Prediction Models for Asian Ever-Smokers

INTRODUCTION

Although lung cancer prediction models are widely used to support risk-based screening, their performance outside Western populations remains uncertain. This study aims to evaluate the performance of 11 existing risk prediction models in multiple Asian populations and to refit prediction models for Asians.

METHODS

In a pooled analysis of 186,458 Asian ever-smokers from 19 prospective cohorts, we assessed calibration (expected-to-observed ratio) and discrimination (area under the receiver operating characteristic curve [AUC]) for each model. In addition, we developed the "Shanghai models" to better refine risk models for Asians on the basis of two well-characterized population-based prospective cohorts and externally validated them in other Asian cohorts.

RESULTS

Among the 11 models, the Lung Cancer Death Risk Assessment Tool yielded the highest AUC (AUC [95% confidence interval (CI)] = 0.71 [0.67-0.74] for lung cancer death and 0.69 [0.67-0.72] for lung cancer incidence) and the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial Model had good calibration overall (expected-to-observed ratio [95% CI] = 1.06 [0.90-1.25]). Nevertheless, these models substantially underestimated lung cancer risk among Asians who reported less than 10 smoking pack-years or stopped smoking more than or equal to 20 years ago. The Shanghai models were found to have marginal improvement overall in discrimination (AUC [95% CI] = 0.72 [0.69-0.74] for lung cancer death and 0.70 [0.67-0.72] for lung cancer incidence) but consistently outperformed the selected Western models among low-intensity smokers and long-term quitters.

CONCLUSIONS

The Shanghai models had comparable performance overall to the best existing models, but they improved much in predicting the lung cancer risk of low-intensity smokers and long-term quitters in Asia.

Low-intensity daily smoking and mortality risk among Mexican women

OBJECTIVE

To examine the association between low-intensity smoking (10 or less cigarettes per day) and all-cause and cause-specific mortality risk among women who smoke and by age at cessation among women who previously smoked.

METHODS

In this study, 104 717 female participants of the Mexican Teachers' Cohort Study were categorised according to self-reported smoking status at baseline (2006/2008) and were followed for mortality through 2019. We estimated HRs and 95% CIs for all-cause and cause-specific mortality using multivariable Cox proportional hazards regression models with age as the underlying time metric.

RESULTS

Smoking as few as one to two cigarettes per day was associated with higher mortality risk for all causes (HR: 1.36; 95% CI 1.10 to 1.67) and all cancers (HR: 1.46; 95% CI 1.05 to 2.02), compared with never smoking. Similarly, slightly higher HRs were observed among participants smoking ≥3 cigarettes per day (all causes HR: 1.43; 95% CI 1.19 to 1.70; all cancers HR: 1.48; 95% CI 1.10 to 1.97; cardiovascular disease HR: 1.58; 95% CI 1.09 to 2.28).

CONCLUSIONS

In this large study of Mexican women, low-intensity smoking was associated with higher mortality risk for all causes and all cancers. Interventions are needed to promote cessation among women who smoke at low-intensity in Mexico, regardless of how few cigarettes they smoke per day.

Light cigarette smoking and all-cause mortality in Spain. A national population-based cohort study

PURPOSE

Regular light cigarette consumption (light smoking) is increasing in many countries; however, few studies have assessed its impact on mortality. The main aim of this study is to estimate the association between the number of cigarettes consumed and all-cause mortality in Spain while focusing on light smoking.

METHODS

Longitudinal study based on data from 42,902 individuals aged ≥15 years included in the 2011-2012 (Spanish) National Health Survey or the 2014 European Health Survey for Spain. Data were linked with the mortality registry up to December 2020. Multivariate Cox regression models were used to estimate hazard ratios (HR) adjusted for sociodemographic variables, lifestyle factors, and health status indicators.

RESULTS

Compared to never smokers, the mortality HR for nondaily smokers was 1.30 (95% CI: 0.81-2.09), increasing to 2.23 (95% CI: 1.25-3.96) among those smoking 1-2 cigarettes/d, and to 1.54 (95%CI: 1.14-2.07) for consumers of 3-5 cigarettes/day. When individuals who reported trying to quit during the previous year were excluded, resulting HRs were 1.31 (95% CI: 0.81-2.10), 1.48 (95% CI: 0.69-3.19) and 1.64 (95% CI: 1.16-2.34), respectively.

CONCLUSIONS

Compared to never smokers, consumers of small quantities of tobacco, that is, light smoking, had an increased mortality risk. In view of these results, we suggest the need for awareness-raising campaigns regarding how smoking even a small number of cigarettes a day causes serious harm to one´s health.

Tobacco smoking and risks of more than 470 diseases in China: a prospective cohort study

BACKGROUND

Tobacco smoking is estimated to account for more than 1 million annual deaths in China, and the epidemic continues to increase in men. Large nationwide prospective studies linked to different health records can help to periodically assess disease burden attributed to smoking. We aimed to examine associations of smoking with incidence of and mortality from an extensive range of diseases in China.

METHODS

We analysed data from the prospective China Kadoorie Biobank, which recruited 512 726 adults aged 30-79 years, of whom 210 201 were men and 302 525 were women. Participants who had no major disabilities were identified through local residential records in 100-150 administrative units, which were randomly selected by use of multistage cluster sampling, from each of the ten diverse study areas of China. They were invited and recruited between June 25, 2004, and July 15, 2008. Upon study entry, trained health workers administered a questionnaire assessing detailed smoking behaviours and other key characteristics (eg, sociodemographics, lifestyle, and medical history). Participants were followed up via electronic record linkages to death and disease registries and health insurance databases, from baseline to Jan 1, 2018. During a median 11-year follow-up (IQR 10-12), 285 542 (55·7%) participants were ever hospitalised, 48 869 (9·5%) died, and 5252 (1·0%) were lost to follow-up during the age-at-risk of 35-84 years. Cox regression yielded hazard ratios (HRs) associating smoking with disease incidence and mortality, adjusting for multiple testing.

FINDINGS

At baseline, 74·3% of men and 3·2% of women (overall 32·4%) ever smoked regularly. During follow-up, 1 137 603 International Classification of Diseases, 10th revision (ICD-10)-coded incident events occurred, involving 476 distinct conditions and 85 causes of death, each with at least 100 cases. Compared with never-regular smokers, ever-regular smokers had significantly higher risks for nine of 18 ICD-10 chapters examined at age-at-risk of 35-84 years. For individual conditions, smokers had significantly higher risks of 56 diseases (50 for men and 24 for women) and 22 causes of death (17 for men and nine for women). Among men, ever-regular smokers had an HR of 1·09 (95% CI 1·08-1·11) for any disease incidence when compared with never-regular smokers, and significantly more episodes and longer duration of hospitalisation, particularly those due to cancer and respiratory diseases. For overall mortality, the HRs were greater in men from urban areas than in men from rural areas (1·50 [1·42-1·58] vs 1·25 [1·20-1·30]). Among men from urban areas who began smoking at younger than 18 years, the HRs were 2·06 (1·89-2·24) for overall mortality and 1·32 (1·27-1·37) for any disease incidence. In this population, 19·6% of male (24·3% of men residing in urban settings and 16·2% of men residing in rural settings) and 2·8% of female deaths were attributed to ever-regular smoking.

INTERPRETATION

Among Chinese adults, smoking was associated with higher risks of morbidity and mortality from a wide range of diseases. Among men, the future smoking-attributed disease burden will increase further, highlighting a pressing need for reducing consumption through widespread cessation and uptake prevention.

FUNDING

British Heart Foundation, Cancer Research UK, Chinese Ministry of Science and Technology, Kadoorie Charitable Foundation, UK Medical Research Council, National Natural Science Foundation of China, Wellcome Trust.

Binary cutpoint and the combined effect of systolic and diastolic blood pressure on cardiovascular disease mortality: A community-based cohort study

Objectives

This study aimed to examine the risk of cardiovascular disease (CVD) death according to blood pressure levels and systolic and/or diastolic hypertension.

Methods

From 20,636 cohort participants, 14,375 patients were enrolled after patients with prior hypertension on antihypertensive drugs were excluded. For the combination analysis, participants were divided into four groups (systolic/diastolic hypertension, systolic hypertension only, diastolic hypertension only, and non-hypertension). The risk of CV death was calculated using the hazard ratio (HR) and 95% confidence intervals (95% CI) in a Cox regression model.

Results

The risk of CVD death increased in systolic hypertension (HR = 1.59, 95% CI 1.26–2.00) and systolic/diastolic hypertension (HR = 1.84, 95% CI 1.51–2.25). The highest risks of hemorrhagic and ischemic stroke were observed in the diastolic hypertension (HR = 4.11, 95% CI 1.40–12.06) and systolic/diastolic hypertension groups (HR = 2.59, 95% CI 1.92–3.50), respectively. The risk of CVD death was drastically increased in those with SBP≥120 mmHg/DBP≥80 mmHg. The highest risk was observed in those with SBP of 130–131 mmHg and 134–137 mmHg.

Conclusion

The combined analysis of systolic and/or diastolic hypertension appears to be a good predictor of CVD death. The risk of CVD death in the prehypertensive group could be carefully monitored as well as in the hypertensive group, presumably due to less attention and the lack of antihypertensive treatment.

Low-intensity cigarette smoking and mortality risks: a pooled analysis of prospective cohort studies in Japan

BACKGROUND

Increasing proportions of smokers in Japan smoke <10 cigarettes per day (CPD). Yet, the health risks of low-intensity smoking in Asia are poorly understood.

METHODS

We performed a pooled analysis of 410 294 adults from nine population-based prospective cohort studies participating in the Japan Cohort Consortium. Cigarette-use data were collected at each study baseline in 1983-1994. Study-specific hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause and cause-specific mortality were calculated using multivariable-adjusted Cox regression by CPD among current smokers and by age at cessation among former smokers, with never smokers as the referent group. Pooled HRs and CIs were computed using a random-effect model.

RESULTS

The smoking prevalence was 54.5% in men and 7.4% in women. About 15.5% of male and 50.4% of female current smokers smoked 1-10 CPD (low-intensity). Both male and female low-intensity smokers had higher all-cause mortality risks than never smokers. Risks were further higher with increasing CPD in a dose-response manner. HRs (95% CIs) were 1.27 (0.97-1.66), 1.45 (1.33-1.59) and 1.49 (1.38-1.62) for 1-2, 3-5 and 6-10 CPD, respectively, in men; 1.28 (1.01-1.62), 1.49 (1.34-1.66) and 1.68 (1.55-1.81) for 1-2, 3-5 and 6-10 CPD, respectively, in women. Similar associations were observed for smoking-related causes of death. Among former low-intensity smokers, younger age at cessation was associated with lower mortality risk.

CONCLUSIONS

Smoking very low amounts was associated with increased mortality risks in Japan. All smokers should quit, even if they smoke very few CPD.