Aim: The present master’s thesis aimed at developing, conducting and evaluating a validation study for the German Patient-Reported Outcomes version of the Common Terminology Criteria for Adverse Events (PRO-CTCAE) core item set. This newly developed instrument was analysed regarding its characteristics and psychometric criteria.

Methods: A patient questionnaire was distributed in ten study centres in the German-speaking area to test the German PRO-CTCAE core item set for item quality and test accuracy. Item quality was assessed by analysis of the raw data, examination of the dimensionality by explorative factor analysis as well as determination of item difficulty, discrimination index, and homogeneity. The psychometric criteria reliability and validity were determined describing together the test accuracy. Reliability was calculated as Cronbach’s alpha coefficient. For construct validation, PRO-CTCAE, EORTC QLQ-C30, and OMDQ were correlated in a Multitrait-Multimethod Matrix (MTMM). Different subgroups of patients were additionally compared to evaluate known group validity. P values were adjusted with Benjamini-Hochberg’s step-up procedure if necessary.

Results: 262 patients participated in the validation study. Patients were on average 60 years old, mainly female and diagnosed with different types of cancer, whereby breast cancer was predominant. Analysis of item quality resulted in a meaningful scaling for the PRO-CTCAE core item set and showed only little improvement opportunities of the German translation. Reliability was very good with correlation coefficients greater than 0.9 for almost all scales. Construct validity as strongest type of validity was confirmed by the MTMM fulfilling all the demanded criteria. Known group validity was also proven for impaired versus preserved quality of life. The main limitations of the study were a missing scoring manual for the PRO-CTCAE, the usage of the insufficiently validated OMDQ and the high proportion of breast cancer patients.

Conclusion: The German PRO-CTCAE core item set is a reliable and valid instrument for patient self-reporting of adverse events in clinical trials. This item pool could usefully supplement the assessment of subjective symptoms by physicians and thereby provide a fuller picture of patients’ experience.