13 COST-EFFECTIVENESS ESTIMATES IN A DOUBLY RANDOMIZED PREFERENCE DESIGN

Thursday, October 18, 2012
The Atrium (Hyatt Regency)
Poster Board # 13
INFORMS (INF), Applied Health Economics (AHE)

Quang A. Le, PharmD, PhD, Western University of Health Sciences, Pomona, CA, Jason N. Doctor, PhD, University of Southern California, Los Angeles, CA, Lori Zoellner, PhD, University of Washington, Seattle, WA and Norah Feeny, PhD, Case Western Reserve University, Cleveland, OH

Purpose: Traditional randomized controlled trials are widely accepted as the gold standard for estimating causal treatment effects. However, they have a significant limitation as strong preferences (or against) one treatment may influence outcomes and/or willingness to participate. To address this limitation, a doubly randomized preference trial (DRPT) has been proposed. We derived the incremental cost-effectiveness ratios (ICERs) for the treatment-preference effects for DRPTs.

Methods: In DRPT, participants are randomly assigned into a “choice” or “no-choice” arm. Participants can choose their preferred treatment (treatment A or B) in the “choice” arm; while in the “no-choice” arm, participants are again randomized into either treatment A or B. With data from a DRPT, the effects of treatment choices on outcomes can be estimated.

Results: ICER for the overall treatment-effect can be estimated (given treatment choice vs. given no-choice of treatment):  ICEROverall_TPE = {(TPEA + TPEB)cost} / {(TPEA + TPEB)QALY}.  ICER for the treatment-preference of treatment A (TPEA):  ICERTPE_A = {(TPEA)cost} / {(TPEA)QALY}.  ICER for the treatment-preference of treatment A (TPEB):  ICERTPE_B = {(TPEB)cost} / {(TPEB)QALY}.   Where,  TPE= {Π(1 - p)µA(A) - (1 - Π)pµB(A)} and  TPEB = {(1 - Π)pµB(B) - Π(1 - p)µA(B)}µA(A) and µB(B) are the estimated mean outcomes corresponding to patients who received their preferred treatment A and B in the choice arm, respectively. µB(A) and µA(B) are the estimated mean outcome corresponding to patients who receive treatment A and B but actually prefer treatment B and A, respectively. And µ can be the estimated mean cost or QALY outcome. Π is the estimated proportion of the population who prefer treatment A and (1 – Π) is the estimated proportion of the population who prefer treatment B. And p is the proportion of patients who are randomly assigned to treatment A, and (1 – p) is the proportion of those randomized to treatment B.  Using data from a DRPT examining the treatment effect and treatment-preference effects between cognitive behavioral therapy (CBT) and pharmacotherapy with sertraline (SER), we estimated the ICERs for the overall treatment-preference effect, treatment-preference of CBT, and treatment preference of SER to be dominant, $22,494/QALY (less cost and less QALY), and $15,647/QALY, respectively. 

Conclusion: ICER estimates for the effects of treatment choices in DRPT are established and can be used in cost-effectiveness studies.