# Preplanned Studies: Trends and Challenges for Population Health and Migration — China, 2015−2050

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• ### Summary

Along with the quick change of society and health transformation, as well as the continued expansion of urbanization, the health risk and its variation of migrants in China would became more complicated.

What is added by this report?

Although a decreasing net migration flow trend was presented from 2015 to 2050, an increasing pace of aging and younger-age trend of migrants would pose serious challenges for population health in China. Deepening aging trend of migrants contributes to the increment of the disease burden of non-communicable diseases (NCDs) and disabilities, and the upward trend of young-age migrant patients with infectious diseases remain a threat to the future intervention and prevention of infectious diseases.

What are the implications for public health practice?

Health policies to eliminate the adverse effects of migration on population health should pay more attention to meet the health care demands of highly vulnerable migrant populations, such as very older and very young migrants.

•  [1] Chen J. Internal migration and health: re-examining the healthy migrant phenomenon in China. Soc Sci Med 2011;72(8):1294 − 301. http://dx.doi.org/10.1016/j.socscimed.2011.02.016CrossRef [2] Li CF, Liu HY, Liang Y, Wang H, Li QH. Study on international comparison of healthy life expectancy and prediction of healthy life expectancy in China. Populat J 2018;40(1):5 − 17. http://dx.doi.org/10.16405/j.cnki.1004-129X.2018.01.001 (In Chinese). CrossRef [3] Li Y, Chen SF, Dong XJ, Zhao XJ. Prediction of cause-specific disability-adjusted life years in China from 2018 through 2021: a systematic analysis. Public Health 2020;180:90 − 9. http://dx.doi.org/10.1016/j.puhe.2019.11.006CrossRef [4] Lutz W, Goujon A, Wils A Forecasting human capital: using demographic multi-state methods by age, sex, and education to show the long-term effects of investments in education. Working Paper WP-07-03, Washington, DC: Education Policy and Data Center, Academy for Educational Development, 2005. https://www.epdc.org/sites/default/files/documents/Forecasting%20Human%20Capital.pdf. [5] Xing R, Yu G, Zheng J, Kim S, Wang L, Shih S, et al The rise of China’s supercities: new era of urbanization. Report from Morgan Stanley Wealth Management Australia Pty Ltd, Australia: Morgan Stanley Wealth Management Astralia Pty Ltd Publication, 2019. [6] Qiao WY, Le L, Guan WH, Wang X, Wang XG. Prediction of urbanization level in China: 2016−2050. Econom Geogr 2018;38(2):51 − 8. http://dx.doi.org/10.15957/j.cnki.jjdl.2018.02.007 (In Chinese). CrossRef [7] Gao CL, Wei HK. Prediction study on the urbanization trends of China. Mod Econom Sci 2013;35(4):85 − 90. http://dx.doi.org/10.3969/j.issn.1002-2848.2013.04.010 (In Chinese). CrossRef [8] Duan CR, Xie DH, Lv LD From the single flow to the dimensional, multi-level and diversified flow: trends of population mobility in China. Beijing Daily, 2019-07-15. http://bjrb.bjd.com.cn/html/2019-07/15/content_11895929.htm. (In Chinese). [9] United Nations Non-communicable diseases and migration. New York: United Nations Publication, 2018. https://www.iom.int/sites/default/files/our_work/DMM/Migration-Health/mhd_infosheet_ncds_10.09.2018.pdf. [10] Gong P, Liang S, Carlton EJ, Jiang QW, Wu JY, Wang L, et al. Urbanisation and health in China. Lancet 2012; 379(9818):843-52. https://www.iom.int/sites/default/files/our_work/DMM/Migration-Health/mhd_infosheet_ncds_10.09.2018.pdf.
• FIGURE 1.  Population-Development-Environment prediction results of population pyramids by urban and rural, China 2015–2050. (A) Population Pyramid in urban, 2015; (B) Population Pyramid in rural, 2015; (C) Population Pyramid in urban, 2030; (D) Population Pyramid in rural, 2030; (E) Population Pyramid in urban, 2050; (F) Population Pyramid in rural, 2050.

FIGURE 2.  The predicted trends of net migration flow, China 2015–2050. (A) Total net migration flow, China 2015–2050; (B) Net migration flow aged 60+ years old, China 2015–2050; (C) Net migration flow aged 0–17 years old, China 2015–2050.

FIGURE 3.  The predicted trend of net migration flow and population health conditions, China 2015–2050. (A) The trend of non-communicable diseases (NCDs) among 60+ years old net migrants and NCDs caused Disability Adjusted of Life Years (DALY), China 2015–2050; (B) The trend of 60+ years old net migrants and disabilities, China 2015–2050; (C) The trend of communicable diseases among 0–15 years old net migrants and communicable, maternal, neonatal, and nutritional diseases caused DALY, China 2015–2050.

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###### 通讯作者: 陈斌, bchen63@163.com
• 1.

沈阳化工大学材料科学与工程学院 沈阳 110142

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## Trends and Challenges for Population Health and Migration — China, 2015−2050

View author affiliations

### Summary

Along with the quick change of society and health transformation, as well as the continued expansion of urbanization, the health risk and its variation of migrants in China would became more complicated.

What is added by this report?

Although a decreasing net migration flow trend was presented from 2015 to 2050, an increasing pace of aging and younger-age trend of migrants would pose serious challenges for population health in China. Deepening aging trend of migrants contributes to the increment of the disease burden of non-communicable diseases (NCDs) and disabilities, and the upward trend of young-age migrant patients with infectious diseases remain a threat to the future intervention and prevention of infectious diseases.

What are the implications for public health practice?

Health policies to eliminate the adverse effects of migration on population health should pay more attention to meet the health care demands of highly vulnerable migrant populations, such as very older and very young migrants.

• 1. Institute of Population Research, Peking University, Beijing, China
• 2. APEC Health Science Academy, Peking University, Beijing, China
###### doi: 10.46234/ccdcw2020.141
• Migration has been one of the most important drivers of socioeconomic progress. However, owing to their unfavorable socioeconomic conditions and barriers to resources, migrants often become the vulnerable and marginalized group at high risk of health problems in China (1). Along with the quick change of society and health transition, as well as the continued expansion of urbanization, the health risk and its variation of migrants in China would became more complicated. To better understand the future trend and population health challenges of migrants are essential for strengthening the health system. Based on Sample Census in 2015 and second hand data, this study used Population-Development-Environment (PDE) model and epidemiological calculations to present a glimpse into the future trend and population health of migrants. An increasing pace of aging and younger-age trend in migrants poses serious challenges for population health. To meet the health care demands of highly vulnerable migrants are needed for eliminating the adverse effects of migration on population health.

2015 Sample Census used in this study was implemented by National Bureau of Statistics, which provided the most detailed data on population and covered 31 provinces in China. Second hand health data was mainly from Global Health Data Exchange, the prediction results based on Second National Sample Survey on Disability and previous publications (23). PDE model and epidemiological calculations were used to predict the trends of migrants and the population health status in 2015–2050, respectively. The mathematical expressions of PDE are as following:

 $${{\rm{P}}_{{\rm{(t + 1,n + 1)}}}}{\rm{ = }}{{\rm{P}}_{{\rm{(t,n)}}}}{\rm{ \times }}\left( {{\rm{1 - }}{{\rm{D}}_{{\rm{(t + 1,n + 1)}}}}} \right){\rm{ + }}{{\rm{N}}_{{\rm{(t + 1,n + 1)}}}}$$ (1)
 $${{\rm{P}}_{{\rm{(0,n + 1)}}}}{\rm{ = }}\sum\limits_{i = 15}^{49} {\left[ {{\rm{ }}{{\rm{F}}_{{\rm{(t,n + 1)}}}}{\rm{ \times F}}{{\rm{R}}_{{\rm{(t,n + 1)}}}}} \right]{\rm{ \times }}\left( {{\rm{1 - }}{{\rm{D}}_{{\rm{(0,n + 1)}}}}} \right)}$$ (2)
 $${{\rm{F}}_{{\rm{(0,n + 1)}}}}{\rm{ = }}{{\rm{P}}_{{\rm{(0,n + 1)}}}}{\rm{ \times f}}{{\rm{r}}_{{\rm{n + 1}}}}$$ (3)
 $${\rm{P}}{{\rm{T}}_{{\rm{n + 1}}}}{\rm{ = }}\sum\limits_{i = 1}^m {{{\rm{P}}_{{\rm{(t,n)}}}}{\rm{ + }}{{\rm{P}}_{{\rm{(0,n + 1)}}}}}$$ (4)

where, t, n, P, D, and N represent the age, year, population, mortality rate and net migration flow, respectively. F, FR, and fr represent the number of women, the fertility rate for specific age groups and the proportion of women with the newborn population, respectively. PT and m represent the total population and the highest age of the population, respectively. More details could be found in Supplementary Figure S1 and previous study (4).

PDE model was based on different scenarios assumptions, and the predictive parameters of scenario assumptions include total fertility rate (TFR), life expectancy (LE) and urbanization rate (UR). TFR in 2015−2017 was set up based on National Fertility Intention Survey, and was assumed to decline since 2017 and reached 1.60 in 2018−2050. According to the Outline of Healthy China 2030 Plan, LE in 2020 was assumed to be 77 years old and 80 years old in 2030. By 2050, LE would reach to 85 years old according to China's General Program for Sustainable Development. UR in 2020 was set up to be 60% according to the National New Urbanization Plan (2014−2020), and would be around 70% in 2030 and around 80% in 2050 based on the experts’ judgements (5-7). More details could be found in Supplementary Tables S1-S3.

PDE results showed that China was facing rapid aging in future. Although two-child policy may make contribution to raising fertility levels which alleviated aging progress to some extent, the aging trend would be irreversible. Moreover, higher aging progress of rural population was found due to rural-urban population mobility (Figure 1).

Figure 1.  Population-Development-Environment prediction results of population pyramids by urban and rural, China 2015–2050. (A) Population Pyramid in urban, 2015; (B) Population Pyramid in rural, 2015; (C) Population Pyramid in urban, 2030; (D) Population Pyramid in rural, 2030; (E) Population Pyramid in urban, 2050; (F) Population Pyramid in rural, 2050.

A gradual downward trend of net migration flow was found in China from 2015 to 2050, which was similar to our previous prediction work by using 2000 and 2010 census. Net migrant flow would be reached 22.57 million by 2030, and 17.57 million by 2050. Although migrants showed a decreasing trend in the future, the huge population size of migrants may slow down the improvement of health level. From 2015 to 2050, both proportion and scale of older net migrants aged 60 years old and above showed upward trends. Moreover, younger-age trend was found in net migrants of China. The proportion of children aged 0–15 years old would increase and reach the peak number in 2025–2029 and then began to fall (Figure 2).

Figure 2.  The predicted trends of net migration flow, China 2015–2050. (A) Total net migration flow, China 2015–2050; (B) Net migration flow aged 60+ years old, China 2015–2050; (C) Net migration flow aged 0–17 years old, China 2015–2050.

The upward tendency of older net migrants and the younger-age trend may play the negative role in population health of China. The deepening aging trend of net migrants would contribute to the increment of the disease burden of non-communicable diseases (NCDs) and disabilities. NCDs causing Disability Adjusted of Life Years (DALY) presented an increasing tendency from 2015–2050. Meanwhile, the scale of older migrants with NCDs also showed a trend of increase. Further, from 2015–2050, the prevalence of disabilities (unadjusted prevalence) would keep increasing which may be as the result of population aging, and the ascending of aging in migrants may aggravate the conditions of disabilities in China. Additionally, although DALY related to communicable, maternal, neonatal, and nutritional diseases would decrease from 2015–2050, the upward trend of migrants aged 0–15 years old with infectious diseases would increase the pressure of infectious diseases intervention and prevention (Figure 3).

Figure 3.  The predicted trend of net migration flow and population health conditions, China 2015–2050. (A) The trend of non-communicable diseases (NCDs) among 60+ years old net migrants and NCDs caused Disability Adjusted of Life Years (DALY), China 2015–2050; (B) The trend of 60+ years old net migrants and disabilities, China 2015–2050; (C) The trend of communicable diseases among 0–15 years old net migrants and communicable, maternal, neonatal, and nutritional diseases caused DALY, China 2015–2050.
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