Activity and participation in haemophiliacs: Item response modelling based on international classification of functioning, disability and health.

Objective: There is scant research investigating the user-friendly functional assessment tool conceptualized by the International Classification of Functioning, Disability and Health (ICF) among persons with haemophilia (PWH). This study aims to accomplish two goals: (1) quantifying comprehensive functioning measures of haemophilia through Item Response Theory (IRT); (2) discussing patient-centred care based on the Wright map of personal ability and item difficulty.

Methods: A cross-sectional study was carried out in 70 PWH (mean age, 33.09 ± 11.04) via convenience sampling. All patients completed the 45 ICF categories of haemophilic-specific activity and participation. Psychometric properties of the categories were examined using Mokken scale analysis and parametric item response modelling.

Results: We extracted a unidimensional scale with 31 categories, and constructed a Rasch model with good fitness. The Cronbach's α of the scale was .9713, with the Guttman's λ2  = .9730, Molenaar Sijtsma ρ = .9802, and latent class reliability coefficient = .9769, indicating great internal reliability. The estimated individual social competence by the Rasch model was highly related to the index score of the three-level EuroQol five-dimensional questionnaire (EQ-5D-3L) (p < .001, r = .62), and had a moderate correlation (p < .001, r = .54) with the score of Haemophilia Activities List (HAL).

Conclusions: The ICF scale of haemophilic activity and participation with 31 categories (HAPPY-ICF) has good construct validity and internal consistency. The person-item threshold distribution map might be helpful in research and clinical practices for patient-oriented care.