Investigating Potential Gender-Based Differential Item Functioning for Items in the Kansas City Cardiomyopathy Questionnaire (KCCQ) Physical Limitations Domain

Women with heart failure report worse health-related quality of life on average, than men. This may result from actual differences in care or differing interpretations of and responses to survey questions. We investigated potential gender-based differential item functioning on the Kansas City Cardiomyopathy Questionnaire (KCCQ) Physical Limitations domain. Using data from the HF-ACTION trial, a multicenter, randomized controlled trial of exercise training in patients with chronic heart failure with reduced ejection fraction (661 women, 1670 men), we assessed gender-based differential item functioning using a Wald test based on item response theory and ordinal logistic regression. Both methods evaluated how men and women responded to each KCCQ item after adjusting for physical limitation status. No item exhibited statistically significant differential item functioning using the Wald method. Two items exhibited differential item functioning using the ordinal logistic regression method (KCCQ1e: Climbing a flight of stairs without stopping; KCCQ1f: Hurrying or jogging) ( P < 0.01), but the magnitude of differential item functioning was negligible. To accurately measure patient-reported outcomes, it is important to evaluate potential biases that may influence the ability to compare patient subgroups. The magnitude of differential item functioning on a 5-item KCCQ Physical Limitation domain was negligible.