A better world towards convergence of longevity?
Authors: Ailiana Santosa
Journal: The Lancet (2017)

Forecasting life expectancy by age and sex is broadly used for research and planning of health sevices, social services, pensions, and economics, and has been developed at the national and multicountry levels.1Raftery AE Li N Sevcikova H et al.Bayesian probabilistic population projections for all countries.Proc Natl Acad Sci USA. 2012; 109: 13915-13921Crossref PubMed Scopus (165) Google Scholar, 2Booth H Tickle L Mortality modelling and forecasting: a review of methods.Ann Actuarial Sci. 2008; 3: 3-43Crossref Google Scholar, 3Alkema L Gerland P Raftery AE et al.The United Nations probabilistic population projections: an introduction to demographic forecasting with uncertainty.Foresight (Colch). 2015; 2015: 19-24PubMed Google Scholar The basic idea for predicting life expectancy is closely related to the concept of epidemiological transition.4Omran AR The epidemiologic transition. A theory of the epidemiology of population change.Milbank Q. 1971; 49: 509-538Crossref Scopus (1940) Google Scholar However, the idea is neither entirely based on evidence nor well-defined methodologically.2Booth H Tickle L Mortality modelling and forecasting: a review of methods.Ann Actuarial Sci. 2008; 3: 3-43Crossref Google Scholar Improvement in life expectancy is achieved through reductions in infant and younger age mortality and the progressive delay of mortality among older people.5Santosa A Wall S Fottrell E et al.The development and experience of epidemiological transition theory over four decades: a systematic review.Global Health Action. 2014; 7: 23574Crossref PubMed Scopus (96) Google Scholar Given the lack of comparable longitudinal mortality data and the difficulty in understanding the outputs from compound forecasting modelling, it is clear that better longitudinal data about age-specific mortality are needed to reliably predict extending longevity. In The Lancet, Vasilis Kontis and colleagues6Kontis V Bennett JE Mathers CD Li G Foreman K Ezzati M Future life expectancy in 35 industrialised countries: projections with a Bayesian model ensemble.Lancet. 2017; (published online Feb 21.)http://dx.doi.org/10.1016/S0140-6736(16)32381-9PubMed Google Scholar have tried to avoid the pitfalls of such modelling. Using probabilistic projections from 21 different models with a 90% complete dataset, the authors predict that life expectancy will increase uninterruptedly in 35 industrialised countries by 2030 with a persistent female advantage. The sex difference is predicted to diminish by 2030 in most industrialised countries, except in Mexico, Chile, France, and Greece. A high probability of surpassing the maximum human lifespan that was considered as a potential maximum by some researchers,7Olshansky SJ Carnes BA Cassel C In search of Methuselah: estimating the upper limits to human longevity.Science. 1990; 250: 634-640Crossref PubMed Scopus (426) Google Scholar, 8Dong X Milholland B Vijg J Evidence for a limit to human lifespan.Nature. 2016; 538: 257-259Crossref PubMed Scopus (262) Google Scholar is predicted in men and women.6Kontis V Bennett JE Mathers CD Li G Foreman K Ezzati M Future life expectancy in 35 industrialised countries: projections with a Bayesian model ensemble.Lancet. 2017; (published online Feb 21.)http://dx.doi.org/10.1016/S0140-6736(16)32381-9PubMed Google Scholar The study notes the extensive shortage of relevant data about unexpected events (eg, climate fluctuations and disease outbreaks) and changes in social determinants (eg, migration patterns and economic crises), which lead to uncertainties in projections of life expectancy. Most population projections are deterministic models, using simple extrapolations, and take into account the non-linearity observed. Hence, these models are unable to determine the probability of the uncertainty of future trends.2Booth H Tickle L Mortality modelling and forecasting: a review of methods.Ann Actuarial Sci. 2008; 3: 3-43Crossref Google Scholar This study proposes a Bayesian method for probabilistic projection of multiple models to fully capture the uncertainty of future trends in mortality and life expectancy. The study predicted uninterrupted gains of life expectancy with a higher probability for men (85%) than for women (65%) in 35 countries, with sex gaps in life expectancy expected to shrink in all countries, except in Mexico. Female life expectancy would break the 90-year barrier with a more than 50% probability by 2030, a barrier believed unreachable at the turn of the 21st century. The forecasts of life expectancy at birth are broadly similar to the UN predictions.9UN Department of Economic and Social AffairsWorld population prospects: the 2015 revision. United Nations, New York2015Google Scholar The findings raise crucial issues about which responses are appropriate to tackle such worsening disparity in terms of health policy and provision of health services. Identifying the best model for forecasting life expectancy will help assess appropriate health prevention strategies in different populations. In terms of relevant policy implications, this study provides substantial evidence of longevity gains and identifies the groups predicted to have a greater contribution to gains. Accurate forecasting of life expectancy is needed. Country differences in life expectancy over 25 years remain. Global Health 203510Jamison D Summers L Alleyne G et al.Global Health 2035: a world converging within a generation.Lancet. 2013; 382: 1898-1955Summary Full Text Full Text PDF PubMed Scopus (786) Google Scholar indicates that most low-income and middle-income countries achieved a "grand convergence" in health. Countries are moving towards universal health coverage. Forecasting life expectancy at birth and at age 65 years can help governments and health services to make the right investments in health, such as averting deaths due to infectious diseases and reducing maternal and child mortality. Achieving universal health coverage is worthy, plausible, and needs to be continued. I declare no competing interests. Future life expectancy in 35 industrialised countries: projections with a Bayesian model ensembleThere is more than a 50% probability that by 2030, national female life expectancy will break the 90 year barrier, a level that was deemed unattainable by some at the turn of the 21st century. Our projections show continued increases in longevity, and the need for careful planning for health and social services and pensions. Full-Text PDF Open Access