Approach to Fixing the Discrepancy Found in the Wu et al . FACT - P to EQ 5 D Mapping Algorithm — Reply to Letter to the

To the Editor – We appreciate Cella et al.’s letter and their interest in the algorithm for predicting EuroQol five-dimensional (EQ-5D) questionnaire scores using Functional Assessment of Cancer Therapy Prostate (FACT-P) questionnaire scores, published in Wu et al. In the letter, the authors raised two primary issues with the algorithm and proposed a modification. We welcome the opportunity to reply to these concerns. First, the authors pointed out that while using the proposed algorithm, the predicted mean EQ-5D values were out of range. In response to this issue, we would like to emphasize a crucial step in the algorithm. Table 4 on page 412 provides the final full algorithm with and without EORTC. The algorithm, however, also requires a truncation of the predicted value of EQ-5D at the final step to ensure the correct range of the predicted value. This has been mentioned in page 410 of the published article: