Covid-19 mortality is negatively associated with test number and government effectiveness

Abstract

A question central to the Covid-19 pandemic is why the Covid-19 mortality rate varies so greatly across countries. This study aims to investigate factors associated with cross-country variation in Covid-19 mortality. Covid-19 mortality rate was calculated as number of deaths per 100 Covid-19 cases. To identify factors associated with Covid-19 mortality rate, linear regressions were applied to a cross-sectional dataset comprising 169 countries. We retrieved data from the Worldometer website, the Worldwide Governance Indicators, World Development Indicators, and Logistics Performance Indicators databases. Covid-19 mortality rate was negatively associated with Covid-19 test number per 100 people (RR = 0.92, P = 0.001), government effectiveness score (RR = 0.96, P = 0.017), and number of hospital beds (RR = 0.85, P < 0.001). Covid-19 mortality rate was positively associated with proportion of population aged 65 or older (RR = 1.12, P < 0.001) and transport infrastructure quality score (RR = 1.08, P = 0.002). Furthermore, the negative association between Covid-19 mortality and test number was stronger among low-income countries and countries with lower government effectiveness scores, younger populations and fewer hospital beds. Predicted mortality rates were highly associated with observed mortality rates (r = 0.77; P < 0.001). Increasing Covid-19 testing, improving government effectiveness and increasing hospital beds may have the potential to attenuate Covid-19 mortality.

Figure 1

Correlation between Covid-19 mortality rate and test number. Countries were categorized by income group (a–c): (a) High-income (N = 59), (b) Middle-income (N = 75), (c) Low-income (N = 19); by governemnt effectiveness scores (d–f): (d) High effectivenss scores (N = 50), (e) Moderate effectiveness scores (N = 50), (f) Low effectiveness scores (N = 51); by percentage of people aged 65 or older (g–i): (g) High percentages of aged persons (N = 49), (h) Moderate percentages of aged persons (N = 49), (i) Low percentages of aged persons (N = 49); by number of hospital beds (j–l): (j) High numbers of beds (N = 45), (k) Moderate numbers of beds (N = 43), (l) Low numbers of beds (N = 46). Lines are linear predictions of Covid-19 mortality rate on test number. The 95% confidence intervals of the fitted values are shown by grey areas (r: correlation coefficient).

Figure 2

Correlation between observed and predicted Covid-19 mortality rates. The 45-degree line indicates equality of observed and predicted Covid-19 mortality rates (r: correlation coefficient; N = 99).