Trends in the kidney cancer mortality-to-incidence ratios according to health care expenditures of 56 countries

The incidence and mortality rates in kidney cancer (KC) are increasing. However, the trends for mortality have varied among regions over the past decade, which may be due to the disparities in medical settings, such as the availability of frequent imaging examinations and effective systemic therapies. The availability of these two medical options has been proven to be positively correlated with a favorable prognosis in KC and may be more common in countries with better health care systems and greater expenditures. The delicate association between the trends in clinical outcomes in KC and health care disparities warrant detailed observation. We applied a delta-mortality-to-incidence ratio (δMIR) for KC to compare two years as an index for the improvement in clinical outcomes and the mortality-to-incidence ratio (MIR) of a single year to evaluate their association with the Human Development Index (HDI), current health expenditure (CHE) per capita, and CHE as a percentage of gross domestic product (CHE/GDP) by using linear regression analyses. A total of 56 countries were included based on data quality reports and missing data. We discovered that the HDI, CHE per capita, and CHE/GDP were negatively correlated with the MIRs for KC (p < 0.001, p < 0.001, and p < 0.001, respectively). No significant association was observed between the δMIRs and the HDI, CHE per capita, and CHE/GDP among the included countries, and only the CHE/GDP shows a trend toward significance. Interestingly, the δMIRs related with an increase in relative health care investment include δCHE per capita and δCHE/GDP.