Psychometrics of patient-reported bother from side effects of treatment single-items in industry-sponsored oncology trials

Improvements in cancer treatment have increased the number of cancer survivors, but also increased the long-term and late effects from cancer therapy. Patient reported “side effect bother” could be used to measure the burden of treatment, and the risk for negative outcomes such as dose reduction, treatment delay or discontinuation. The current study addresses the psychometric properties of a single item, determines what represents a “meaningful change”, and evaluates the correlation to safety endpoints and functioning.

Results from 5911 patients enrolled in 8 clinical trials representing 5 disease types in oncology and hematology who completed either the Functional Assessment of Cancer Therapy (FACT) GP5 item or a modified bother item (MBI) were assessed.

Patients ranged in age from 18 to 93 years, with all cancer stages represented and approximately equal numbers of males and females. Test–retest reliability was acceptable, as were convergent and known groups validity. The GP5 and MBI effectively demonstrated sensitivity to change over time and established meaningful thresholds.

The results indicate that these single-items are psychometrically sound, capable of distinguishing known groups, responsive to change and can identify meaningful change over time in terms of treatment-related symptoms. It extends the findings of recent scientific groups by providing analyses not included in prior studies, and further supports the FDA’s recommendation to include a single item question in clinical trials.