General population norms for the Functional Assessment of Cancer Therapy–Kidney Symptom Index (FKSI)

BACKGROUND: Metastatic renal cell cancer is associated with poor long-term survival and has no cure. Traditional clinical endpoints are best supplemented by patient-reported outcomes designed to assess symptoms and function. Normative data was obtained on the National Comprehensive Cancer Network-Functional Assessment of Cancer Therapy-Kidney Symptom Index (NFKSI) to aid in score interpretation and planning of future trials. METHODS: General population data were obtained from 2000 respondents, who completed the 19-item NFKSI-19, as well the SF-36 (Short Form 36-item instrument) and the PROMIS-29 (29-item Patient Reported Outcomes Measurement Information System), both general health status measures. Basic demographic and self-reported comorbidity data were also collected. RESULTS: The sample was 50% female, 85.7% caucasian, with an equal distribution across age bands from 18 years to 75 years and older. Most respondents (62.8%) had more than a high school education and reported an Eastern Cooperative Oncology Group performance status of normal activity without symptoms (63.4%). Score distributions on the NFKSI-19, its subscales, and individual items are summarized. CONCLUSIONS: The NFKSI-19 and its subscales now have scores for the general US population, allowing comparability to generic questionnaires such as the SF-36 and PROMIS-29. These data can be used to guide treatment expectations and plan future comparative effectiveness research using the scales.