OBJECTIVES: To determine proper methods for incorporating AEMTs into HTA assessments, including (a) which AEMTs to include, (b) how to value them, and (c) the proper level of disaggregation for use in patient-centered valuation models.

METHODS: We first review available literature for advice on inclusion of AEMTs. We then identify from economic theory the proper value measure for AEMTs and review available estimates of magnitudes of value associated with health losses from AEMTs in contrast to health gains from beneficial medical interventions. We discuss health care as a bundled set of commodities with beneficial gains and adverse events, and show why proper methods for valuing the adverse events do not simply treat them as negative health gains.

RESULTS: Many analyses either ignore AEMTs, or count only those with medical costs incurred (and count only the costs, not health losses). Common recommendations use only Grade 3 or higher AEMTs, while Grade 2 events (for example) can cause important losses in quality of life, including losses in instrumental Activities of Daily Living (ADL). We demonstrate that the proper method for valuing AEMTs is the Willingness to Accept (WTA) risks, not Willingness to Pay (WTP) for health gains. We summarize a literature suggesting that WTA exceeds WTP by factors up to 5X or more in health-related situations. We also demonstrate that most evaluations of AEMTs overly aggregate them, thus masking important differences in rates of different AEMTs that matter differently to different patients.

CONCLUSIONS: Proper incorporation of AEMTs requires major revision from current protocols in terms of which AEMTs are included, how they are evaluated, and how they are reported in the scientific literature. Repairing these deficits will require more refined data than currently available and important shifts in the way AEMTs are included in cost-effectiveness and other HTA models.