We thank Velasco Montes et al. for their interest in our article Gasto sanitario público y mortalidad por COVID-19 en España y en Europa [Public healthcare expenditure and COVID-19 mortality in Spain and in Europe].1 It is true that we did not include models adjusted for other sociodemographic, economic, or other variables because our aim was to analyze whether the widespread and uncritically accepted relationship between the “scarcity” of resources and outcomes2,3 was able to be verified empirically.

It is possible, but not probable, that the lack of a relationship between public healthcare expenditure and mortality due to COVID-19 may change after adjusting for other variables. After adjustment, Medeiros et al. did not find an association between healthcare expenditure and the mortality rate4 whereas Khan et al. paradoxically found that the higher healthcare expenditure is as a percentage of GDP (%HE/GDP), the higher the case fatality rate.5

The development of adjusted models requires that the variables introduced have a clinical-epidemiological significance and show an independent association with robust outcome variables. The case fatality rate is dependent on the efficacy of epidemiological surveillance and %HE/GDP does not indicate the real expenditure. Nevertheless, if we are able to develop suitable adjustment models, we will attempt to take on the challenge proposed by Velasco Montes et al.1