Background: Patient reports of expected treatment side effects are increasingly collected as part of the assessment of patient experience in clinical trials. A global side effect item that is patient-reported has the potential to inform overall tolerability. Therefore, the aim of this study was to examine the completion and distribution of such a global single-item measure of side effect burden in five cancer clinical trials.
Methods: Data from five trials from internal Food and Drug Administration databases that included the Functional Assessment of Cancer Therapy-General single-item measure of overall side effect burden (i.e. impact on degree of bother) were analyzed. Completion rates for the side effect bother item, items adjacent to this item, and two non-adjacent items on the Functional Assessment of Cancer Therapy-General that are related to health-related quality of life were calculated at the baseline assessment and at the 3-month assessment. To evaluate the distribution, the percentage of patients reporting high levels (quite a bit or very much bother) of side effect bother at baseline and 3 months was assessed.
Results: Completion rates for all items were at least 80% regardless of time point or trial population. However, in three of the five trials, completion rates for the side effect bother item were lower at baseline compared to adjacent and non-adjacent items. This difference was not observed at 3 months. Up to 9.4% of patients reported high levels of side effect bother at baseline.
Conclusion: Patients may enter trials already reporting some bother from side effects. This can make interpretation of results with respect to the investigational agent under study challenging. Patients may skip an item evaluating side effect bother at baseline, suggesting some difficulty with interpretation of what is being asked. Further study of the wording and utility of a baseline side effect bother assessment is warranted.
Keywords: Side effect; cancer; patient-reported outcome; trial.