Inter-Rater Reliability, Construct Validity, and Feasibility of the Modified "Which Health Approaches and Treatments Are You Using?" (WHAT) Questionnaires for Assessing the Use of Complementary Health Approaches in Pediatric Oncology.

< 0.001]). The mean scores of the feasibility scale (out of 7.0) for the self- and proxy-report were 5.64 (SD = 0.23) and 5.81 (SD = 0.22), respectively, indicating the feasibility of the modified WHAT; Conclusions: The findings provide initial evidence of the reliability and validity of the modified WHAT and their feasibility. Further research is needed to test the theoretical relationships and further explore the validity and reliability of the modified WHAT.