Impact of changes in tobacco smoking prevalence on death, dementia and disability in England and Wales, 2017–2040: A modelling study

Abstract

Background There is considerable morbidity and mortality associated with smoking globally and in the UK. We aimed to estimate the impact of two scenarios for reduction of smoking prevalence on numbers of deaths, life expectancy and incidence of dementia and disability to 2040 in England and Wales. Methods A probabilistic Markov model, IMPACT-BAM, was developed to integrate calendar trends in incidence of cardiovascular disease (CVD), dementia, disability and mortality to forecast future prevalence of these conditions in addition to numbers of deaths from cardiovascular and non-cardiovascular causes in the population of England and Wales. Disability is defined as the inability to independently conduct one or more basic activities of daily living. Data from the English Longitudinal Study of Ageing (ELSA) and Office for National Statistics were used to inform the model. Systematic reviews and meta-analyses of published literature provided relative risks of CVD, dementia, disability and mortality for smokers versus non-smokers, by age and sex. These estimates were used to modify model parameters and forecast the impact of smoking on mortality, dementia and disability to 2040 under three scenarios: S1. Prevalence of smoking remains at 2017 levels, 19% in men and 17% in women, up to 2040 (baseline scenario); S2. Prevalence of smoking is reduced to 9% by 2020 and 5% by 2025 (taper scenario); S3. Smoking is eliminated by 2020 (elimination scenario). Results If prevalence of smoking remains at 2017 levels (S1), there will be an estimated 952,000 (95% Uncertainty Interval 808,000–1153,000) deaths from cardiovascular causes and 10,624,000 (9,562,000–11,776,000) deaths from non-cardiovascular causes between 2017 and 2040. If prevalence of smoking declines gradually to 2025 (S2) 35,000 (29,000–43,000) CVD deaths and 408,000 (373,000–443,000) non-CVD deaths could be prevented or postponed. If smoking is eliminated (S3), the corresponding figures are 84,000 (68,000–105,000) and 843,000 (764,000–907,000) deaths. If prevalence of smoking remains constant (S1), cumulatively between 2017 and 2040, 5,073,000 (95%UI 4,868,000–5,256,000) persons are estimated to develop dementia and 6,690,000 (95%UI 6,483,000–6,869,000) persons are estimated to develop disability. 34,000 (22,000–40,000) incident cases of dementia and 57,000 (47,000–73,000) cases of disability can be prevented or postponed under the taper scenario S2. A tot l of 56,000 (17,000–88,000) cases of dementia and 113,000 (52,000–160,000) cases of disability can be prevented or postponed under the elimination scenario S3. Under the stable smoking prevalence scenario (S1) LE at 65 will increase from 21.8 years (95% UI 21.7, 22.0) in 2017 to 26.4 years (95%UI 23.8, 29.9) by 2040. LE at 65 in 2040 is estimated to increase by an additional half a year under S2 (26.9 (24.2, 30.6)) and an additional year under S3 (27.4 [24.5, 31.1]). Half the increase in LE will be free of dementia and disability. Conclusion Public health programs targeting tobacco smoking can potentially have a considerable effect on postponing deaths from cardiovascular and non-cardiovascular causes and yield gains in life expectancy free of dementia and disability.