Burden of disease information is widely used internationally as evidence for strategic health policy. Information on the levels and trends in health loss and health expectancy by age, sex, cause, year and country provides the ‘big picture’ of health need and how well a health system is performing.
Reports from the study
- Health Loss in New Zealand 1990–2013 – health loss and health expectancy in New Zealand from 1990 to 2013
Two key metrics employed in this report are the disability-adjusted life year (DALY) and health-adjusted life expectancy (health expectancy).
- The DALY is the unit of health loss. One DALY represents the loss of one year lived in full health. DALYs integrate health losses from premature mortality (years of life lost, YLL) and years lived with disability adjusted for severity (YLD).
- Health expectancy is a generalisation of life expectancy that takes account of time lived in different health states, defined by level of functioning (disability). So health expectancy can be thought of as the number of years the average person can expect to live in full health.
The New Zealand Burden of Diseases, Injuries and Risk Factors extracted data from the Ministry of Health’s national data collections, health surveys and other sources. The Institute for Health Metrics and Evaluation, University of Washington provided statistical models and standards, as part of the Global Burden of Disease 2013 study.
Health is improving
New Zealanders are living longer, and are living longer in good health (ie, both life expectancy and health expectancy are increasing). Health loss, measured in DALYs, is declining by an estimated 1.2% per year, once adjusted for changes in population size and age structure – a major achievement for the health and wider social sectors. Yet because the population is growing and ageing, the absolute number of DALYs is still increasing. This finding suggests that improvements in health do not necessarily reduce health care expenditure.
However, not all age groups are benefiting equally
The rate of fall in DALYs for youth and young adults, 20% and 13% from 1990–2013 respectively, is substantially less than for other age groups, for whom the fall ranges from 24–36%.
New Zealand is far advanced along the ‘epidemiological transition’
For the population as a whole, less than 4% of health loss still results from pre-transitional causes (common infectious diseases, nutritional deficiency disorders and neonatal disorders). In contrast, 88% of health loss is now caused by non-communicable diseases (NCDs – ie, long‑term mental and physical conditions) and 8% is attributable to injuries.
New Zealand is undergoing a ‘disability transition’
The epidemiological transition described above is also reflected in a disability transition. Disability (defined here in terms of non-fatal health loss, measured in YLD) now accounts for over half of the total health loss experienced by the population as a whole (52% of total DALYs in 2013).
Morbidity (ill health) is expanding
We may be living longer, and living longer in good health, but we are also living longer in poor health. Put another way, only 70–80% of the years of life gained over the past quarter century have been years lived in good health: our health system and wider society have proved more adept at preventing early death than at avoiding or ameliorating morbidity. A greater focus on addressing the impact of non-fatal disabling conditions, whether through prevention or improved management, will enable people to live more of their ‘extra’ years of life in full health.
Improving the health of future cohorts of older people will be critical
An ageing population will increase demand pressure on the health system, but the level of this impact will depend on how healthy future cohorts of older people are. As we progress through the epidemiological and disability transitions, it appears that an increasing proportion of frail older people will survive for longer with multi-morbidity and associated disability.
Transitioning the health system to respond to multi-morbidity is a key challenge
The evidence in this report shows that all-cause DALY rates increase exponentially as people age, to reach very high levels in the rapidly growing 75+ years age group. These high rates of health loss reflect the steeply increasing prevalence of multiple long-term conditions with advancing age. A health system oriented to managing single diseases individually will struggle to cope.
Mental health and dementia are growing challenges
Neuropsychiatric disorders are now the leading cause of health loss, accounting for 19% of total DALYs. Dementia has risen to become the fifth-ranked cause of health loss in females and thirteenth in males. Providing better care for people living with mental illness, addiction and dementia – including care for their physical health – is a growing challenge for the health and social sectors.
The burden of musculoskeletal disorders is increasing
Health loss from musculoskeletal disorders, including neck and lower back disorders and arthritis, is increasing – partly because of rising rates of obesity. Musculoskeletal disorders already account for 13% of all health loss.
At the same time, addressing cardiovascular disorders is an unfinished agenda
Although the coronary heart disease epidemic peaked in the 1970s, this disease still accounts for over 8% of all health lost. About 70–80% of this burden is potentially avoidable through a combination of prevention and treatment. Stroke also continues to account for substantial health loss (over 3%) and again most of this loss is potentially avoidable with existing technologies.
Burden is becoming decoupled from prevalence
Many long-term conditions, including diabetes, are increasing in prevalence yet their age adjusted per capita burdens are stabilising or even falling. This decoupling of burden from prevalence applies also to risk factors, including obesity. Decoupling reflects the complex interactions of disease or risk factor prevalence with demographic trends, joint exposure to other risk factors or diseases, and improvements in clinical care that have reduced disease progression and case fatality.
Strengthening prevention could bring major benefits
The opportunity to achieve health gains by reducing exposure to hazards remains strong. Potentially, over one-third of all health loss is preventable. Beyond the benefits to health, a strengthened focus on prevention could help the health system to become more sustainable clinically, fiscally and economically (by reducing demand pressure), depending on the affordability and effectiveness of relevant interventions. Although tobacco use has been declining for almost half a century, its impact on health loss is still large (contributing just under 9% of total DALYs), and the ‘tobacco end game’ remains an important policy objective. Even greater challenges are to address diet, physical inactivity and the obesity epidemic – challenges that go well beyond the health system and will require not only a whole of government but also a whole of society response.
Internationally, New Zealand is doing well, but inequalities persist
Over the past quarter century New Zealand achieved one of the fastest rates of decline in health loss from all causes combined among high-income countries, although we still have relatively high DALY rates from coronary heart disease, chronic obstructive pulmonary disease, chronic kidney disease, bowel cancer and self-harm. Yet within New Zealand, serious inequalities in health outcomes persist between different genders, generations, ethnic and socioeconomic groups. While not all of these inequalities could not be analysed in the current burden of disease assessment because of data limitations, disaggregation of the data at least by Māori and non-Māori ethnicity is planned for the next edition of this report.