Patient preferences for reducing toxicities of treatments for gastrointestinal stromal tumor (GIST)

Abstract

A Brett Hauber¹, Juan Marcos Gonzalez¹, John Coombs², Andres Sirulnik², David Palacios², Norman Scherzer³¹RTI Health Solutions, Research Triangle Park, NC, USA; ²Novartis Pharmaceuticals Corporation, East Hanover, NJ, USA; ³The Life Raft Group, Wayne, NJ, USAPurpose: To quantify gastrointestinal stromal tumor (GIST) patients' preferences for reducing treatment toxicities and the likely effect of toxicities on patients' stated adherence.Methods: English-speaking members of the Life Raft Group, a GIST patient advocacy and research organization, aged 18 years and older, completed a web-enabled survey including a series of treatment-choice questions, each presenting a pair of hypothetical GIST medication toxicity profiles. Each profile was defined by common or concerning toxicities verified via pretest interviews including: severity of edema, diarrhea, nausea, fatigue, rash, hand-foot syndrome, and heart failure; and risk of serious infection. Each subject answered 13 choice-format questions based on a predetermined experimental design with known statistical properties. Subjects were asked to rate the likelihood that they would miss or skip doses of medications with different toxicity profiles. Random-parameters logit was used to estimate a relative preference weight for each level of toxicity.Results: 173 subjects completed the survey. Over the ranges of toxicity levels included in the study, heart failure was the most important toxicity. Edema was the least important. For all toxicities, reducing severity from severe to moderate was more important to subjects than reducing severity from moderate to mild. Reducing heart failure from moderate to mild and diarrhea from severe to moderate had the largest effects on subjects' evaluation of adherence.Conclusions: All toxicities included in the study are important to patients. Treating or reducing severe toxicities is much more important to patients than treating or reducing moderate toxicities. Focused reductions of certain toxicities may improve treatment adherence.Keywords: GIST, toxicities, patient preference, adherence, conjoint analysis, discrete choice experiment