Validation of the patients‐specific functional scale in patients with haemophilia

Introduction A complete functional assessment is essential to measure health status and treatment effects in patients with haemophilia. The Patient‐Specific Functional Scale (PSFS) is a reliable, valid, simple and quick scale that measures physical function in patients with musculoskeletal disorders. However, the reliability and validity of the PSFS have not been evaluated in patients with haemophilia. Aim The aim of this study was to validate the Patient‐Specific Functional Scale in patients with haemophilia. Methods Twenty‐eight patients with haemophilia participated in the study. They completed the PSFS and the Haemophilia Activity List (HAL) scales by telephone during an initial session, and then repeated the assessment in a follow‐up session 1 week apart. Reliability was analysed by the internal correlation coefficient (ICC), the standard error of measurement (SEM) and the smallest detectable change (SDC). The concurrent validity of the PSFS was determined by correlating the initial score of the PSFS scale to the initial score of the HAL scale. Correlations were calculated by means of scatter plots and Pearson product‐moment r correlation coefficient. Results ICC and SEM values showed excellent reliability for the PSFS scale, with a SDC of 1. A significant moderate correlation was found between the results of the PSFS and the HAL (r = .57, P