Important Group Differences on the Functional Assessment of Cancer Therapy-Kidney Symptom Index Disease-Related Symptoms in Patients with Metastatic Renal Cell Carcinoma.

BACKGROUND

The Functional Assessment of Cancer Therapy-Kidney Symptom Index Disease-Related Symptoms (FKSI-DRS) is important to gauge clinical benefit in metastatic renal cell carcinoma (mRCC).

OBJECTIVES

To estimate important difference (ID) in FKSI-DRS scores that is considered to be meaningful when comparing treatment effect between groups, using mRCC trial data.

METHODS

Data were derived from two pivotal phase III mRCC trials comparing sunitinib versus interferon alfa (N = 750) in first-line mRCC, and axitinib versus sorafenib (N = 723) in second-line mRCC. The change from baseline in FKSI-DRS score was examined as a function of a set of anchors using the repeated-measures model. Several anchors were evaluated: FKSI item "I am bothered by side effects of treatment," EuroQol five-dimensional questionnaire utility score, and adverse events.

RESULTS

When the "I am bothered by side effects of treatment" score was used as an anchor, the ID ranged between 1.2 and 1.3 points. When change in the EuroQol five-dimensional questionnaire utility score was used as an anchor, the FKSI-DRS ID ranged between 0.62 and 0.63 points. Selecting the adverse events that corresponded to a maximum worsening in the FKSI-DRS score in either trial, the ID ranged between 0.62 and 0.74 points.

CONCLUSIONS

Among patients undergoing treatment for mRCC, between-group differences in FKSI-DRS scores as low as 1 point might be meaningful.