Why are various average life expectancy and healthy life expectancy figures calculated?

Average life expectancy and healthy life expectancy are calculated based on the calculation method and the type and point of demographic data. It is more important to understand how each data is calculated and what demographic data is used, rather than which one is correct and incorrect.

In order to calculate the average life expectancy, it is necessary to create a life table. A life table is a calculation of how many years people of each age can live on average (life expectancy), assuming that the situation of death in a certain group will not change in the future. If you look at how many years a 0-year-old can live, you can know the average life expectancy. Typical life tables nationwide include a complete life table and a simple life table. The complete life table is created every five years based on the Japanese population (confirmed number) and demographic statistics (confirmed number) according to the census, and the simple life table is based on the estimated population and the monthly report of demographics based on the estimated population. It is created every year based on (approximate figures). For the census year, both a simple life table and a complete life table are created, but the complete life table has the character of a definitive version.

Based on the demographic statistics (confirmed number) for three years before and after the census year and the Japanese population (confirmed number) based on the census, it is created every five years for each prefecture. In this way of creating a life table, the value is different from the average life expectancy in the whole life table. The government recommends that the life table be used for the average life expectancy of the whole country, and the life table by prefecture for the average life expectancy of prefectures (including Yokohama City).

The method of creating this life table is different from the complete life table or the life table by prefecture. Here, the values of Yokohama City and each ward are listed, but it is recommended that the city as a whole use a life table by prefecture. Only the first decimal place has been announced. It is created every 5 years.

While the government calculates the average life expectancy using the Bayes estimation method, Yokohama City uses the Chan method that does not use general Bayes estimation. This is because the Bayes estimation program used by the country has not been published. The government announces the average life expectancy of Yokohama City every five years, and it takes time to announce it, so it was provisionally calculated independently.

Until June 2014, the Ministry of Health, Labour and Welfare research group (Chief researcher = Shuji Hashimoto and Fujita Health University professor) (hereinafter referred to as the research group) published only the figures for prefectures and did not disclose the figures for Yokohama City. For this reason, Yokohama City applied to the government for the provision of data for Yokohama City based on the results of the questionnaire survey on the National Life Basic Survey, and calculated the healthy life expectancy of Yokohama City independently using the calculation program provided by the research group based on the data obtained. The calculation program also calculates the average life expectancy because a life table is created when calculating healthy life expectancy. Here, in addition to "5 Average life expectancy calculated independently by Yokohama City (Chang method)", the average life expectancy of "6 Average life expectancy calculated independently by Yokohama City (using healthy life expectancy calculation program)" is calculated and published. The reasons for this are as follows. When explaining the meaning of generally easy-to-understand healthy life expectancy, “average life expectancy = healthy life expectancy +“ average life expectancy ””, “average life expectancy”, “healthy life expectancy” and “average life expectancy during periods with limited daily life” are calculated using the same calculation program and demographic data. Because if it is not “average life expectancy”, adding “healthy life expectancy” and “average of periods with limited daily life expectancy” does not become “life expectancy”.
In this part, there is confusion in the country. For example, in the healthy life expectancy nationwide in 2010, the figures for Health Japan 21 (secondary) are the same as those for the research group, but "average life expectancy and healthy life expectancy difference" is different for the period limiting daily life. This is because the research group uses the same demographic data and calculation method to calculate healthy life expectancy and life table, while Health Japan 21 (secondary) uses a complete life table for average life expectancy. Because

In December 2012, Yokohama City calculated its own healthy life expectancy, but in July 2014, the research group announced the healthy life expectancy of 20 major cities, including Yokohama City. The values published here are different from the values originally calculated by Yokohama City, but it is thought that the cause is that the aggregate time of the population used as a standard is slightly different from the one used by the research group .

However, the research group said, "It is not determined which method is correct for detailed methods such as which basic numerical values are used when calculating healthy life expectancy. If you specify which basic figures and how they were calculated, even if they were different from those calculated by the research group, they can be said to be the correct figures. "

In addition, there are various other calculation methods for healthy life expectancy. For example, this method calculates healthy life expectancy by using the average life expectancy of each prefecture separately published by the national government instead of using the life table derived from the same demographic.

Furthermore, healthy life expectancy is said to be the "average period during which there is no restriction on daily life" this time, a questionnaire item of the Basic Survey on National Life "You are currently affected by health problems and affect your daily life. Do you? Calculated based on the results of the response. However, "How is your current health condition, such as "average period during which you are aware that you are healthy?" There is also a way of thinking that calculates based on the results of questionnaire responses. There are different ways of seeking healthy life expectancy both in the world and in each country.

Even if you try to find a distinct healthy life expectancy in Yokohama City, the number of data from the questionnaire survey on the National Life Basic Survey, which is a questionnaire survey, will be reduced in each of the 18 wards, and the calculation will be incorrect. Therefore, in Yokohama City, instead of healthy life expectancy, the average independence period of distinction (though this is also said to be one of the types of healthy life expectancy ...) was calculated independently. This is calculated using The Long-term Care Insurance data owned by Yokohama City instead of data from the Basic Survey on People's Life. It is based on the concept of “a period in which daily life is restricted” and “a period in which nursing care is required”, and many other local governments calculate this value and use it as a reference value for health measures. However, there is a considerable difference in numerical values from healthy life expectancy.