A massive international study of health, longevity, and diseases in 188 countries around the world has found that people are generally living longer, with the global life expectancy having risen by more than six years since 1990.

According to data that's just been released from the Global Burden of Disease Study 2013, global life expectancy at birth for both sexes has risen to 71.5 years of age, up 6.2 years from 65.3 years of age in 1990. The main reasons for our longer lifespans are major advances made in fighting HIV/ AIDS and malaria over the past decade, along with progress in managing communicable, maternal, neonatal, and nutritional disorders.

But while people on average are living significantly longer than they used to just a quarter of a century ago, those extra years aren't necessarily easy ones to bear. Healthy life expectancy (HLE), which takes into account the impact of non-fatal conditions such as illness and disability, only rose by 5.4 years in the same period (from 56.9 in 1990 to 62.3 in 2013).

The upshot is we're living longer, but on average we're also spending a greater proportion of our lives living with the hardship caused by disability and illness. Longer lives mean more time spent being old, and it's a sad fact that the elderly experience more significant health problems than younger adults.

"The world has made great progress in health, but now the challenge is to invest in finding more effective ways of preventing or treating the major causes of illness and disability," said lead author Theo Vos from the University of Washington's Institute for Health Metrics and Evaluation, in a statement.

And although the average healthy life expectancy is up around the globe, not every country fared equally well. According to the study, which is published in The Lancet, dozens of countries have only made minor gains. Some nations even went backwards, including South Africa, Paraguay, Belarus, Lesotho, and Swaziland. People born in those last two countries in 2013 can expect to live at least 10 fewer years in good health compared to their compatriots born in 1990.

But of course other nations have made impressive gains in health. The authors of the research single out Ethiopia in this regard, which increased its healthy life expectancy by 13.5 years, more than double the global average. People born in Ethiopia in 1990 could only expect to live 40.8 healthy years – now the figure stands at 54.3 years of good health.

"Ethiopia has made impressive gains in health over the past two decades, with significant decreases in rates of diarrheal disease, lower respiratory infection, and neonatal disorders," said Tariku Jibat Beyene of Addis Ababa University in Ethiopia. "But ailments such as heart disease, COPD, and stroke are causing an increasing amount of health loss. We must remain vigilant in addressing this new reality of Ethiopian health."

Countries with the highest healthy life expectancy, both sexes, 2013:
1. Japan 2. Singapore 3. Andorra 4. Iceland 5. Cyprus 6. Israel 7. France 8. Italy 9. South Korea 10. Canada

Countries with lowest healthy life expectancy, both sexes, 2013
1. Lesotho 2. Swaziland 3. Central African Republic 4. Guinea-Bissau 5. Zimbabwe 6. Mozambique 7. Afghanistan 8. Chad 9. South Sudan 10. Zambia

If you want to know the leading specific causes of death in these countries, you can check out our story right here, and why not take a look at this video too?