Incorporating Process Utility into Cost-Effectiveness Analysis Via a Bolt-On Domain to the SF-6D: An Exploratory Study

Background: Within the UK, standard methods of economic evaluation centre on the maximisation of the quality-adjusted life-year (QALY). However, preference-based measures used to estimate QALYs may not be suited to all economic evaluations, as they routinely measure only health outcomes.

Aim: This study used an economic evaluation alongside a clinical trial (EEACT) comparing patients' preferences for a telephone versus a face-to-face consultation to incorporate process utility into cost-effectiveness analyses.

Methods: An EEACT is described that generates QALYs using Short-form 6-dimension version 1 (SF-6Dv1) responses. These results exclude specific consideration of process utility. A health state valuation study is then reported that bolts a process domain onto the SF-6Dv1 using data obtained from the EEACT. These results therefore include the consideration of process utility. The results of the EEACT with and without process utility are then compared.

Results: This study shows that the QALY, in its current form, does not capture patient benefits associated with the process of receiving healthcare. The EEACT illustrates this, showing a statistically significant difference between control and intervention groups for the patient experience questionnaire communication domain, indicating that patients preferred the intervention. This preference was not identified in the cost-effectiveness outcomes, and the point estimates lie in the north-west quadrant of the cost-effectiveness plane. The preference is captured after adding a communication domain. The point estimate moves to the north-east quadrant, where the intervention is more effective and more costly than the control.

Conclusion: This study indicates that it is possible to capture patients' preferences for processes associated with care, in a format compatible with the QALY.