Development and Validation of a Symptom Illustration Scale from the Patient-reported Outcome Common Terminology Criteria for Adverse Events for Patients with Breast Cancer

Purpose: Emojis are commonly used for daily communication and may be useful in assessing patient-reported outcomes (PROs) in breast cancer. The purpose of this study is to develop and validate a Symptom Illustration Scale (SIS) as a new PRO measurement.

Methods: Eighteen original SIS items were developed from the PRO-CTCAE. In cohort one, the SIS validity and reliability were examined in patients with breast cancer, using a semi-structured five-question survey to investigate content validity. PROs with PRO-CTCAE and SIS were examined twice to determine criteria validity and test-retest reliability. In cohort two, the responsiveness of the scales were examined in patients treated with anthracycline, docetaxel, paclitaxel, and endocrine therapy. PROs with PRO-CTCAE and SIS were investigated two or three times, depending on the therapy.

Results: Patients were enrolled from August 2019 to October 2020. In cohort one (n = 70), most patients had no difficulties with the SIS, but 16 patients indicated that it was difficult to understand severities in the SIS. For criterion validity, Spearman rank correlation coefficients (r) between PRO-CTCAE and SIS items were ≥ 0.41, except for "Decreased appetite." For test-retest reliability, κ coefficients of the SIS were ≥ 0.41 for 16/18 items (88.9%). Response time was significantly shorter for the SIS than for PRO-CTCAE (p < 0.001). In cohort two (n = 106), score changes between PRO-CTCAE and SIS for relevant symptoms all had correlations with r ≥ 0.41.

Conclusion: An original SIS from the PRO-CTCAE for patients with breast cancer were verified the validity, reliability, and responsiveness. Further studies to improve and validate the SIS are needed.