Between-country heterogeneity in EQ-5D-3L scoring algorithms: how much is due to differences in health state selection?

Background EQ-5D-3L scoring algorithms vary amongst countries, not only in the values of regression coefficients but also in the independent variables included in the regression model (hereafter referred to as model specification). It is unclear how much of this variation is due to differences in health state selection, the relative frequencies with which health states were valued, and model diagnostics, rather than to genuine differences in population preferences.