Q&A: Health trends and changes in life expectancy in Japan

Life expectancy increased in Japan, according to a new study published in The Lancet Public Health and led by Keio University Global Research Institute (KGRI) and IHME. This research comprehensively analyzed 30 years (1990 to 2021) of health in Japan to understand trends across its 47 prefectures, 371 diseases/injuries, including COVID-19, and 88 risk factors. 

We spoke with Dr. Shuhei Nomura (IHME collaborator) on these findings.

This transcript has been lightly edited for clarity

Why is it important to have subnational health data for Japan?

Japan’s population keeps getting older, and the pace and the impact of aging varies a lot across prefectures. So we really needed to understand what’s happening at the local level, not just nationally – and if you look at only national-level data, you miss important differences between regions. And, actually, without that kind of breakdown data, local governments don’t really understand, and don’t really know what specific health issues they should be focusing on.

Then, the GBD framework makes this possible – it gives us the comprehensive and standardized data that we can compare across different prefectures over time. That is super important for understanding where we need to take action.

What were the key findings from your research?

We found some really interesting results and trends. Life expectancy is now about 85 years in Japan, but the gap between life expectancy and healthy life expectancy has widened. It’s now over 11 years. Basically, people are living longer, but they are spending more time dealing with health issues.

Another big thing is the growing health disparities between prefectures. Now there is nearly a three-year difference in life expectancy, depending on where you live. Also, Alzheimer’s and other dementias are now the number one cause of death in Japan, which is a huge shift. And the mortality rate for major conditions like stroke, and ischemic heart disease, and lung cancer, and others, they have improved a lot over the decades, but we are seeing those improvements now have been slowing down.

So all of this data tells us that we really need to rethink how we approach public health in Japan.

How will the research findings be used in Japan?

Over the last 30 years, Japan’s life expectancy went up by about 5.8 years. But at the same time, the gap between life expectancy and healthy life expectancy widened. It went from about 10 years to 11 years now. That basically means people are living longer but they’re spending more time with health issues.

And what’s really concerning is that health gaps between prefectures are growing. So, the difference in the life expectancy between the different prefectures used to be 2.3 years at maximum before, 30 years ago, but now it’s 2.9 years. And for men it’s even bigger. It went from 3.2 years to 3.9 years, which is quite a jump.

Figure 2 shows a pretty concerning trend. The blue color indicates a large difference between the healthy life expectancy and life expectancy, and the red color means a very narrow difference. I mean, the gap between life expectancy and healthy life expectancy. So there is a general regional trend: the northern area is less likely to have a bigger gap between life expectancy and healthy life expectancy. But the southern area shows a higher gap. That means people in those areas are more likely to spend more years with disability.

This difference is not just about health care access. It may have a lot to do with complex interactions between health system performance and social determinants of health, which depends on prefectures. So, if we really want to improve health equity across Japan, we also need to look at these deeper social and economic differences between prefectures.

How timely is this research in terms of the development of Japan’s national health plan?

This research actually comes at a really good time because Japan just started the new phase of its national 10-year-long health promotion strategy, which is called Health Japan 21. So, I think the local governments will be able to use our data in order to focus on their own specific health challenges. For example, some prefectures might need to invest more in dementia care because it’s now the leading cause of mortality in Japan, and others might need to work more on reducing mortality risks for major conditions like stroke and ischemic heart disease.

And regarding the growing gap between life expectancy and healthy expectancy, it really tells us we need to focus more on improving quality of life, not just simply extending a lifespan.