Validity and usefulness of a single-item measure of patient-reported bother from side effects of cancer therapy

BACKGROUND

The improving efficacy of cancer treatment has resulted in an increasing array of treatment-related symptoms and associated burdens imposed on individuals undergoing aggressive treatment of their disease. Often, clinical trials compare therapies that have different types, and severities, of adverse effects. Whether rated by clinicians or patients themselves, it can be difficult to know which side effect profile is more disruptive or bothersome to patients. A simple summary index of bother can help to adjudicate the variability in adverse effects across treatments being compared with each other.

METHODS

Across 4 studies, a total of 5765 patients enrolled in cooperative group studies and industry-sponsored clinical trials were the subjects of the current study. Patients were diagnosed with a range of primary cancer sites, including bladder, brain, breast, colon/rectum, head/neck, hepatobiliary, kidney, lung, ovary, pancreas, and prostate as well as leukemia and lymphoma. All patients were administered the Functional Assessment of Cancer Therapy-General version (FACT-G). The single item "I am bothered by side effects of treatment" (GP5), rated on a 5-point Likert scale, is part of the FACT-G. To determine its validity as a useful summary measure from the patient perspective, it was correlated with individual and aggregated clinician-rated adverse events and patient reports of their general ability to enjoy life.

RESULTS

Analyses of pharmaceutical trials demonstrated that mean GP5 scores ("I am bothered by side effects of treatment") significantly differed by maximum adverse event grade (P<.001) in all trials, with a clear trend toward increasing GP5 scores with level of increasing adverse event grade. Effect sizes ranged from 0.13 to 0.46. Analyses of cooperative group trials demonstrated a significant correlation between GP5 and item GF3 ("I am able to enjoy life") in the predicted direction.

CONCLUSIONS

The single FACT-G item "I am bothered by side effects of treatment" is significantly associated with clinician-reported adverse events and with patients' ability to enjoy their lives. It has promise as an overall summary measure of the burden of a given set of treatment toxicities compared with another. Future research can identify the contribution of individual side effects compared with one another in terms of how each may contribute to overall bother. Cancer 2017. © 2017 American Cancer Society.

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