Establishing health state valuations for disease specific states: an example from heart disease

This study considers the feasibility of defining a QALY from disease-specific data using the New York Heart Association (NYHA) classification of heart failure. The study derives health state values for the four different NYHA classifications of disease progression using the time trade-off (TTO) instrument associated with the five dimensional (EQ-5D) health state valuation method. Consistent mappings between the disease classification and the chosen QALY instrument are found. With this being the case, the assumption of constant proportionality, which is necessary to define the QALY as an acceptable measure of health related preferences, is considered. It is found that constant proportionality does not hold across the more severe health states, thus questioning the use of QALYs as representing cardinal preference structures.