經濟成長、所得不平等與人口健康：跨國研究1980-2000

Abstract

背景：經濟成長和所得不平等對人口健康的影響，已被許多研究所驗證，然而隨著二十世紀末經濟全球化的加速，世界各國經濟發展形成顯著的改變，因此有必要進一步檢視經濟成長、所得不平等和人口健康的關係。再者，過去的研究將經濟成長和所得不平等視為兩個獨立的變項，並未考量兩者之間的關係來檢證其對人口健康的影響。 目的：（1）探討1980-2000年經濟成長、所得不平等和人口健康的關係，並指出在高、低所得國家中，經濟成長、所得不平等對人口健康的差異；（2）結合經濟成長和所得不平等形成經濟發展型態的分類，探討1980-2000年不同經濟發展型態國家，人口健康變化的差異，以及經濟發展型態對人口健康改善的影響。 方法：本研究為一跨國區位研究，資料來源為世界發展指標（World Development Indicators 2006）以及世界所得不平等資料庫（World Income Inequality Database），採用1980、1990和2000年的資料。主要的分析涵括了全球77個國家，包括已開發和發展中國家。經濟成長指標選用GDP和GNI的年均成長率，所得分配指標選用吉尼指數，人口健康指標則選用平均餘命、嬰兒死亡率、五歲以下死亡率。第一部份透過迴歸分析檢視經濟成長、所得不平等對人口健康影響，以及在低、高所得國家的差異；第二部分檢視不同經濟發展類型對人口健康的影響。透過年均經濟成長率（大於5%、0%至5%、小於0%）、吉尼指數變化率（大於0%、小於0%），將各國經濟發展型態進行分類為六類：快速成長－所得分配改善（A組，4國）、快速成長－所得分配惡化（B組，6國）、穩定成長－所得分配改善（C組，16國）、穩定成長－所得分配惡化（D組，34國）、經濟衰退－所得分配改善（E組，6國）、經濟衰退－所得分配惡化（F組，11國）。 結果：（1）經濟成長和所得不平等都與平均餘命、嬰兒死亡率以及五歲以下死亡率有顯著的相關：較高LnGDP（LnGNI）和較低的吉尼指數，則平均餘命愈高、嬰兒和五歲以下死亡率愈低。無論是平均餘命、嬰兒死亡率或五歲以下死亡率，吉尼指數的相對影響力在高所得國家較大。在平均餘命的迴歸模型中，吉尼指數和LnGDP（LnGNI）的標準化迴歸係數比值，高所得國家為–0.52（-0.79），低所得國家則為–0.45（-0.48）。在嬰兒死亡率迴歸模型中，高所得國家比值為 –0.61（-0.99），低所得國家為–0.23（-0.25）。從五歲以下死亡率的迴歸模型來看，高、低所得國家的比值則分別為–0.70（-1.40）以及–0.25（-0.27）。（2）經濟衰退國家的人口健康改善較差，特別是當中所得不平等惡化者。1980-2000年間，各組平均零歲平均餘命變化分別為9.31%（A組）、10.45%（B組）、7.43%（C組）、7.39%（D組）)、3.90%（E組）以及–6.18%（F組）；各組平均嬰兒死亡率變化分別為–58.6%（A組）、-47.0%（B組）、-43.0%（C組）、-54.3%（D組）、-30.1% (E組)以及–13.4% （F組）；各組平均五歲以下死亡率變化分別為–58.6%（A組）、-47.0%（B組）、-43.0%（C組）、-54.3%（D組）、-30.1%（E組）以及–13.4%（F組）。多元迴歸分析顯示，在控制了所得、所得不平等、教育和健康支出等指標後，經濟衰退－所得分配惡化對平均餘命、嬰兒死亡率、五歲以下死亡率的改善仍有顯著的負面影響（p<0.05）。 結論：經濟成長和所得不平等對人口健康皆有顯著影響，其中所得不平等對高所得國家的影響比低所得國家來得重要。經濟衰退對人口健康會造成威脅，然而所得分配的改善對經濟衰退國家的人口健康有保護的效果。

Background: Economic growth and income inequality have been regarded as two independent predictors of population health. Economic globalization in the late 20th century, however, had significantly changed the situation of global economy and thus the relationship of economic growth, income inequality and population health must be examined further. Furthermore, former studies considered economic growth and income inequality as independent dimensions, and did not take the relationship of them into account. Objectives: First, to examine the relationship of economic growth, income inequality and population health, and to evaluate the differences in low- and high-income countries. Second, to develop a cross-classification by economic growth and income inequality to evaluate the impacts of different patterns of economic development on population health. Methods: This is an ecological study with pooled cross-sectional time series analyses. Data were obtained from World Development Indicators 2006 and World Income Inequality Database Version 2.0 for the index year 1980, 1990 and 2000. Seventy-seven developed and developing countries were included. Main measures included GDP and GNI annual growth rates as indicators of economic growth; GINI index was used as indicators of income inequality. Population health indicators included life expectancy at birth, infant mortality and under-five mortality. We applied a cross-classification by economic growth (annual growth rate >5%, 0-5% and <0%) and income inequality (GINI index change >0% and <0%) to examine the differences in population health improvement in each groups. The study groups consisted of rapid growth with income inequality improving (group A, N=4), rapid growth with income inequality worsening (group B, N=6), stable growth with income inequality improving (group C, N=16), stable growth with income inequality worsening (group D, N=34), decline with income inequality improving (group E, N=6), decline with income inequality worsening (group F, N=11). Results: (1) Economic growth and income inequality were both significant associated with life expectancy, infant mortality and under-five mortality. Higher LnGDP (LnGNI) and lower GINI index were associated with higher life expectancy and lower infant and under-five mortality. The relative impacts of GINI index to LnGDP (LnGNI) were stronger in high-income countries on life expectancy, infant mortality and under-five mortality. In the regression model of life expectancy, the ratio of standardized regression coefficient of GINI index to LnGDP (LnGNI) was –0.52 (-0.79) in high-income countries and –0.45 (-0.48) in low-income countries. In the regression model of infant mortality, the ratio of standardized regression coefficient of GINI index to LnGDP (LnGNI) was –0.61 (-0.99) in high-income countries and –0.23 (-0.25) in low-income countries. When it came to the regression model of under-five mortality, the ratio of standardized regression coefficient of GINI index to LnGDP (LnGNI) was –0.70 (-1.40) in high-income countries and –0.25 (-0.27) in low-income countries. (2) The population health improvement was worse in economic decline countries, especially in those with income inequality worsening. The average life expectancy change rates during 1980 to 2000 in each study group was 9.31% (group A), 10.45% (group B), 7.43% (group C), 7.39 (group D), 3.90% (group E), and –6.18% (group F). The average infant mortality change rates during 1980 to 2000 in each study group was –58.6% (group A), -47.0% (group B), -43.0% (group C), -54.3% (group D), -30.1% (group E), and –13.4% (group F). The average under-five mortality change rates during 1980 to 2000 in each study group was –58.6% (group A), -47.0% (group B), -43.0% (group C), -54.3% (group D), -30.1% (group E), and –13.4% (group F). The multiple regression analysis showed that economic decline with income inequality worsening had significant negative effect (p<0.05) on the improvement of life expectancy, infant mortality and under-five mortality, even after the adjustment of income, income inequality, education enrollment, and health expenditure. Conclusions: Economic growth and income inequality both had significant impacts on population health. Compared with low-income countries, income inequality had a stronger impact on population health in high-income countries. Economic decline had negative effects on population health. Income inequality improvement, however, had significant protective effects on population health in economic decline countries.