Does the association between smoking and mortality differ due to frailty status? A secondary analysis from the Mexican Health and Aging Study

Frailty: a global health challenge in need of local action

Frailty is a complex, age-related clinical condition that involves multiple contributing factors and raises the risk of adverse outcomes in older people. Given global population ageing trends, the growing prevalence and incidence of frailty pose significant challenges to health and social care systems in both high-income and lower-income countries. In this review, we highlight the disproportionate representation of research on frailty screening and management from high-income countries, despite how lower-income countries are projected to have a larger share of older people aged ≥60. However, more frailty research has been emerging from lower-income countries in recent years, paving the way for more context-specific guidelines and studies that validate frailty assessment tools and evaluate frailty interventions in the population. We then present further considerations for contextualising frailty in research and practice in lower-income countries. First, the heterogeneous manifestations of frailty call for research that reflects different geographies, populations, health systems, community settings and policy priorities; this can be driven by supportive collaborative systems between high-income and lower-income countries. Second, the global narrative around frailty and ageing needs re-evaluation, given the negative connotations linked with frailty and the introduction of intrinsic capacity by the World Health Organization as a measure of functional reserves throughout the life course. Finally, the social determinants of health as possible risk factors for frailty in lower-income countries and global majority populations, and potential socioeconomic threats of frailty to national economies warrant proactive frailty screening in these populations.

Rural and urban differences in lifetime occupation and its influence on mortality among Mexican adults

OBJECTIVE

To determine how primary lifetime occupation type is associated with mortality, and how the relationship varies by rural and urban dwelling.

MATERIALS AND METHODS

Data come from 2001-2018 Mexican Health and Aging Study (adults aged 50+, n=11 094). We created five occupation categories. Cox proportional hazard models predicted mortality using baseline covariates.

RESULTS

In both rural and urban settings, participants with manual jobs, such as agriculture and production/industrial jobs, had an increased risk of mortality compared to those with administrative/professional jobs. In urban settings, participants in the domestic/service and no main job categories had higher risk of mortality than those in the administrative/professional category. For men these differences remained, but not for women.

CONCLUSION

In a context of rural and urban demographic shifts, it is crucial to consider the implications that occupation as a socioeconomic factor can have on health and to identify the most vulnerable groups.

Genetic predisposition to smoking in relation to the risk of frailty in ageing

Frailty causes emerging global health burden due to its high prevalence and mortality. In this study, we used Mendelian randomization (MR) approach to examine the potential causal relationship between smoking and frailty in ageing. Using inverse-variance weighted (IVW) method, genetically predicted smoking initiation was associated with an increased risk of frailty in ageing (odd ratio (OR) 1.23, 95% confidence interval (CI) 1.19-1.27, P = 3.21 × 10^-39). Similarly, per year increase in age of initiation of regular smoking was associated with a 25% decrease in the risk of frailty (95% CI 7-39%, P = 7.79 × 10^-3, per year), while higher number of cigarettes per day was associated with a 12% increased risk (95% CI 4-20%, P = 1.76 × 10^-3). Compared with former smokers, current smokers were associated with an increased risk of frailty (OR 1.12, 95% CI 1.02-1.22, P = 0.01). Lifetime smoking was associated with a 46% higher risk of frailty (95% CI 37-56%, P = 2.63 × 10^-29). Sensitivity analysis using alternative MR methods yielded similar results. Our study indicates that genetic predisposition to smoking is associated with the risk of frailty in ageing. Further studies are warranted to examine the exact role of smoking in the development of frailty.