Limitation
This study has certain limitations. First, the questionnaire booklets’ assignment to the patients was quasi-randomized and not strictly randomized with random numbers generated. Additionally, the medical staff could identify the questionnaire booklet types if they looked inside them. Thus, we cannot dismiss the possibility that they distributed the questionnaire booklets in an order different from instruction. However, they had no motivation to allocate these questionnaire booklets selectively to the patients with specific characteristics. Indeed, the patients’ observed characteristics were not unbalanced. Second, the patients might not have answered from the questionnaire booklet’s start, thus resulting in the order effects’ underestimation. Third, the order effects’ impact on the EQ-5D-5L may be different from this study when more severe patients or other disease-specific instruments are examined.