Prophylactic use of treatment is important for good outcomes in haemophilia, yet adherence can be suboptimal. To better understand the relationship between treatment adherence and patients' beliefs about treatment there is a need to quantify patients' treatment attitudes. The aim of this study was to develop a brief, clinically relevant, patient-reported outcome (PRO) to measure ease of use and patients' preference for haemophilia treatment. A 40-item questionnaire was completed by male adults with haemophilia A from Austria, Germany, Italy, Spain and the UK. Robust statistical methods for item evaluation including item-level statistics, dimensionality analyses and input from clinical and outcomes experts were used to inform item reduction. Retained items were subjected to psychometric evaluation including exploratory factor analysis (EFA), known-groups validity and internal consistency reliability. 273 patients completed the questionnaire. Of the 40 items, 28 items were flagged for possible deletion based on item-level statistics, three of which were retained due to clinical relevance. Two items had acceptable statistical performance but were deleted based on low clinical relevance. A total of 13 items were retained. EFA produced a conceptually defined 5-factor solution. The survey had acceptable known-groups validity and internal consistency. Refinements were made to wording and scoring, and one new item was added to assess general ease of use, resulting in a 14-item questionnaire - the HaemoPREF. Preliminary measurement properties of the HaemoPREF support the instrument to evaluate patient perception and preference for haemophilia treatment. Further psychometric evaluation is required to examine and confirm the measurement properties of the scale.
Keywords: HaemoPREF; convenience; ease of use; haemophilia; preference; psychometric.
© 2014 John Wiley & Sons Ltd.