Development of Attributes and Attribute Levels for a Discrete Choice Experiment on Patients' and Providers' Choice for Antiretroviral Therapy Service in Northwest Ethiopia

Background: Discrete choice experiments (DCEs) are used to assess the strength of preferences and value of interventions. However, researchers using this approach have been criticized for not conducting or publishing rigorous studies to select the required attributes and levels. Proper specification of attributes and their levels determines the validity of DCE. Hence, our study aimed to identify and define attributes and levels for the design of a DCE to elicit patients' and providers' preferences for ART service in Northwest Ethiopia.

Methods: Four stages were followed to derive the final list of attributes and levels: (1) a literature review to derive conceptual attributes; (2) key informant interviews of 17 providers and in-depth interviews of 15 adult stable patients to identify context-specific attributes and attribute levels; (3) ranking survey among 31 HIV/AIDS program implementers and rating survey among 35 adult stable patients and 42 health workers providing antiretroviral therapy (ART) service to indicate participants' preference of attributes; and (4) an expert opinion to reduce the list of attributes and levels.

Results: First, a literature review identified 23 candidate attributes. Second, individual-level analysis of the qualitative transcripts confirmed 15 of these 23 attributes. Third, the ranking and rating surveys put the importance of the 23 ART service attributes in order of preference. Fourth, through discussions with eight experts, 17 attributes were discarded based on multiple criteria. The six retained attributes were: the location of ART refills, the frequency of receiving ART refills, the person providing ART refills, the participants/others seen at the same ART refill visit, medication refill pick-up/delivery times, and the total cost of the visit during antiretroviral (ARV) medication refill. Finally, levels were assigned to these 6 attributes based on data from the literature, transcripts, and knowledge of the Ethiopian context.

Conclusions: This detailed description illuminates the attribute development process and provides the reader with a basis for evaluating the rigor of this phase of DCE construction. This paper contributes empirical evidence to the limited methodological literature on attributes and levels of development for DCE, thereby providing further empirical guidance on ART service preference, specifically among patients of low- and middle-income countries.