ABSTRACT
Women diagnosed with heart failure report worse quality of life than men on patient-reported outcome (PRO) measures. An inherent assumption of PRO measures in heart failure is that women and men interpret questions about quality of life the same way. If this is not the case, the risk then becomes that the PRO scores cannot be used for valid comparison or to combine outcomes by subgroups of the population. Inability to compare subgroups validly is a broad issue and has implications for clinical trials, and it also has specific and important implications for identifying and beginning to address health inequities. We describe this threat to validity (the psychometric term is differential item functioning), why it is so important in heart-failure outcomes, the research that has been conducted thus far in this area, the gaps that remain, and what we can do to avoid this threat to validity. PROs bring unique information to clinical decision making, and the validity of PRO measures is key to interpreting differences in heart failure outcomes.