Inequality-Adjusted Human Development Index as an Important Predictor of Deaths Caused by Non-Communicable Diseases in the World and Iran: An Ecological Study

Background and Objectives: The main purpose of this study was to compare the predictive power of the Inequality-adjusted Human Development Index (IHDI) with the Human Development Index (HDI) with regard to the share of deaths caused by Non-Communicable Diseases (NCD) among all deaths in the world and Iran.   Methods: The data required for this cross-sectional ecological study were extracted from the reports of the United Nations Human Development Program and the WHO in 2015. Pearson correlation test was used to investigate the correlation of HDI and IHDI with the share of deaths caused by NCDs and linear regressions models were used to determine the associations of IHDI and HDI with the dependent variable.   Results: At a significant level of P<0.01, the dependent variable showed a strong positive correlation with HDI (0.892) and IHDI (0.899). Simple linear regression showed that HDI alone predicted the dependent variable well (Adj.R2=0.794, P<0.001).However, according to the multivariate linear regression model, when IHDI and HDI were included in the model, IHDI was able to predict the dependent variable well (Adj.R2=0.809, P=0.001), while the relationship between HDI and the dependent variable was no longer significant.   Conclusion: Although HDI alone is an important predictor of NCD status, it loses its influence in the presence of IHDI. Therefore, in addition to HDI, IHDI that illustrates the impact of inequality on human development can provide more information on the status of deaths caused by NCDs.