“…So nearly 90% of the variation in per capita health expenditure in 13 countries is explained by the variation in per capita GDP [ 29 , 30 ]. Numerous subsequent papers corroborate the empirical evidence of the link between aggregate income and health expenditure [ 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ]. These findings have been generalised in studies in European Union countries, in the G7 and the Seven Emerging Markets (EM7) [ 50 ], in the 15 member countries of the Economic Community of West African States (ECOWAS) [ 51 ], and in countries as politically and socially distant as China and the United States [ 52 ].…”