In the light of the 1997 WHO Health Report, the Director-General of WHO, Dr. Hiroshi Nakajima stated that increased longevity without quality of life is an empty prize. Health expectancy is more important than life expectancy. The experience of the European Union (EU) underlines the need to focus on health. Health and healthy population is fundamental to the pursuit of smart, sustainable and inclusive growth and better jobs. More healthy life years mean a healthier workforce, and less retirement on the grounds of ill health. It reduces the burden on formal and informal care structures, leading to less strain on public finances and contributing to the longer-term sustainability of the health and social systems as the population ages [4].

A range of factors impact the health status of ageing populations therefore it cannot be simply assumed how the healthy life expectancy (disability trends) will develop in next decades. For example, rising obesity might cause future increases in unhealthy lifespan, whereas improvements in medical technologies such as joint replacements can contribute towards lower disability rates and higher healthy life years [2]. Assumptions, therefore, cannot be made on the development of morbidity and disability in the next decades, and on the interaction between declining mortality, morbidity and disability. Such uncertainty over health and disability trends, combined with current data limitations, entails the need to model different scenarios. For almost 50 years, there has been much debate over whether people will live longer, healthier lives - the compression of morbidity scenario, longer but more disabled/ ill-health lives - the expansion of morbidity scenario, or something in between - the dynamic equilibrium scenario[5,6]. In order to examine these different hypotheses, life expectancy per se is not a sufficient indicator and needs to be completed with a level of health status. Lifespan without or with disability/ill-health defines the average number of years a person at a certain age is expected to live in the particular health condition. Health expectancies, combining life expectancy with a concept of health - chronic disease, functional limitations, activity restrictions, physical, mental or social well-being - have become essential indicators of the health of the ageing populations, where the quality of remaining life is considered to be equally important as the quantity [7,8]. There are as many possible health expectancies as relevant health indicators [9]. Disability-free life expectancies (DFLE) are commonly used as to refer to a relevant measure of health of the population, and in particular of older cohorts. For the sake of comparability of data and of the more effective measuring of the health status of all Europeans, the European Commission developed a Healthy Life Years (HLY) indicator which is the part of the family of DFLE, being based on a general activity limitation indicator (GALI) [10], and introducing a concept of quality of life [9]. The HLY was presented in the set of structural indicators selected and defined to help measure progress of the 2000 Lisbon strategy objectives [11].

Realising the importance of health as a determinant and a driver of economic growth and competitiveness, the European Commission decided to include public health policy into its economic Lisbon Agenda [12]. HLY indicator was introduced to monitor health as an economic/productivity and societal welfare factor [12].

The Europe 2020 strategy, a successor of the Lisbon Strategy, therefore, highlights the ageing of the EU population as one of pressing societal challenges, calling for actions to foster active and healthy ageing. Health and healthy population is fundamental to the pursuit of smart, sustainable and inclusive growth and better jobs [13].

In one of its flagship initiatives – Innovation Union - Europe 2020 proposed launching a European Innovation Partnership on Active and Healthy Ageing that aims to address the challenge of ageing through innovation [14]. The Partnership sets a headline target to increase HLY at birth on EU average by 2 years by 2020. It is an ambitious yet firm health goal that strives to reduce the socio-economic risks associated with demographic change and to underpin quality of life of all Europeans and especially the older Europeans.

The objective of this paper is to provide analytical research that supported the European Commission in setting the target of increasing healthy lifespan of Europeans by 2 years by 2020. Similarly to life expectancy projections predicting an increasing trend for the next few decades, the paper explores the possible effect of continually postponing death on the overall prevalence of morbidity and disability. It explores three scenarios of HLY trends - compression of morbidity, expansion of morbidity, intermediary dynamic equilibrium - which give a range of possible values to be achieved by 2020 on the basis of which the Partnership selected the goal to be pursued.

The first scenario, proposed by Fries [15,16] assumes that life expectancy is reaching its limit, and the period of ill-health and disability before death is shortened. This theory has two parts: delays in the onset of chronic disease/disability in later life, and one stage in the progression of chronic disease [17]. Accordingly, morbidity and disability are gradually compressed into the shorter span between the increasing age at onset of morbidity and the age at death, and the number of years spent with diseases or disability decreases over time.

The expansion of morbidity hypothesis, developed by Gruenberg and Kramer [18,19] states that mortality reductions will produce more years with morbidity and related disability. The decline in mortality is largely due to the decreasing fatality rate of diseases, rather than a reduction in their incidence. The final stage of the progress of fatal chronic disease is delayed and mainly due to life-sustaining medical interventions. Consequently, declining mortality from fatal diseases does expand longevity but with a substantial increase in the population at high risk of chronic morbidity and related disability. This induces a shift in the distribution of causes of disability from fatal toward less fatal or nonfatal diseases.

This alternative intermediate hypothesis, suggested by Manton [20], states that there exists equilibrium between life expectancy and the health and functioning of the elderly population. In this scenario increased survival does produce an increase in years with morbidity, but years with severe morbidity and disability are relatively constant, because the pace of progression of chronic diseases and disability is reduced. In other words, the proportion of a life span lived with serious illness or disability decreases, whereas the proportion with moderate disability or less severe illness increases. As declines in the rate of disease progression delay the onset of more serious disease states, the dynamic equilibrium scenario implies that mortality reductions will be associated with a redistribution of disease and disability from more to less severe states [5].

Such inter-country differences in values of LE and HLY across the EU make it difficult to model any EU level projections.

Predictions about the likely effect of the continually delaying death on the period of morbidity and disability at the end of life depend on the causal factors that are driving this trend. As previously emphasised, data limitations make confident interpretation of past trends nearly impossible, thus hindering the robust computing of future scenarios. This means a great level of uncertainty for predicting which scenario might prevail. Difficulties in forecasting the development of health expectancies (here HLY) reinforce the conclusions of other studies which contend that gaps in existing health data impede the modelling on the basis of the past trends of health status and health expectancy [5]. This makes it difficult to establish any coherent set of hypotheses for projections of health status [5]. In addition, other factors that might influence the health of future cohorts (e.g. changes in life style such as higher obesity levels or the opportunity to introduce new medical technologies) were not considered in the study despite the fact that these factors would affect the predicted HLY under the different scenarios.

Following results observed under the different scenarios (Table ​(Table1),1), the potential HLY target could foresee an increase by 2 years for men and 1.4 years for women at the EU level. It is a ‘grand’ goal but can be reached in next couple of years.

However, the big challenge is how to reflect MS levels of health development in the EU average health indicator. Statistics clearly show that EU countries characterise very different levels of health progress, with a gap of 2 decades and diverging trends. With this in mind, the EU HLY target should be complemented by national HLY targets for men and women, set by MSs. It would make MSs feel equally responsible for the delivery of the HLY target, regardless of their starting positions. In addition, accompanying the EU headline target with national targets would be in line with the Europe 2020 approach breaking with ‘one size fits all’ approach.

There is an urgent need for action and intervention at different levels in order to close a gap between a number of life years and those lived in good health, disability or frailty free.

It should be nevertheless emphasized that the identification of HLY as a headline target for one of Europe 2020 key initiatives is a move forward towards development of comparable, robust and sustainable health indicators. Given the multifaceted goals of the Partnership aiming to improve not only health status but also quality of life, this initiative is a great opportunity to develop a comprehensive monitoring framework based on a set of indicators that monitor health, quality of life, while supporting active ageing and employment in the context of lengthening of life, with sound and comparable, less subjective data.