Pre-Treatment Health Related Quality of Life and Stratified Cost-Effectiveness Analysis

Introduction: This paper demonstrates that standard cost-effectiveness screening of pharmaceutical drugs may give misleading results if systematic data heterogeneity by base health related quality of life (BHRQoL), the HRQoL immediately prior to treatment, is ignored. Study Design: It is argued that for some chronic diseases, such as rheumatoid arthritis, the magnitude of the HRQoL response to a specific pharmacotherapy may be negatively correlated with BHRQoL, and that the net cost of the pharmacotherapy may be positively correlated with BHRQoL. It is also argued that the value placed on a given increment in HRQoL declines as HRQoL rises. It is shown that if these factors are ignored costeffectiveness analysis (CEA) based on sample averages will give misleading results, and that CEA applied to the data stratified by BHRQoL is indicated. Methods: The case for sample stratification by BHRQoL, and for conducting costeffectiveness analysis (CEA) at the stratum level, is illustrated with numerical examples using hypothetical data and the incremental net monetary benefit (INMB) criterion. Sensitivity analysis is used to explore the response of the INMB at the stratum level to different degrees of data heterogeneity across the strata. Results: Due to cumulative effects, even relatively minor data heterogeneity by BHRQoL results in substantial differences in the cost-effectiveness of treatment across strata. CEA stratified by BHRQoL enables a more efficient and equitable allocation of public healthcare funding.