• Discrete choice experiments (DCEs) that elicit patient preferences are increasingly being conducted, and their role in decision making is increasing. One of the key outputs of a DCE is the marginal rate of substitution (MRS), but it has been suggested in the literature that reporting of uncertainty around MRSs is inadequate.
• In this study, a systematic literature review was conducted to determine the frequency with which DCE studies that elicit patient preferences reported MRS without information on the degree of uncertainty. An analysis was also conducted to determine how standard errors (SEs) of MRSs calculated using commonly reported information compare with the actual SEs.
• The degree of uncertainty around MRS estimates was not reported in over one-third of patient preference DCE studies that reported MRS. The analysis indicated that estimates of SEs calculated using commonly reported information are often significantly biased when covariances (typically not reported) are not included in calculations. Thus, it is crucial that researchers calculate and report SEs of MRSs.