The Timed Up and Go Test in Patients with Haemophilia: Assessing Reliability, Validity, and Predictive Variables

The Timed Up and Go (TUG) test is frequently used to assess patients' functional mobility. However, its psychometric characteristics in patients with haemophilia (PwH) are unknown. This study's primary aim was to determine the validity, reliability, standard error of measurement (SEM), and minimal detectable change (MDC) of the TUG in PwH. The secondary aim was to determine predictors for the TUG time.A total of 40 PwH were included. Test-retest reliability was assessed by the same rater at two time points and inter-rater reliability was assessed by two raters. Construct validity was tested via correlation analyses between the TUG and the haemophilia joint health score (HJHS), the short physical performance battery (SPPB), the HEP-Test-questionnaire, and the Haemophilia Activity List (HAL). SEM and MDC were calculated. Multiple linear regression analyses with several patient-specific predictors were performed.Test-retest and inter-rater reliability analyses revealed excellent ICCs of 0.990 (95% CI: 0.972-0.995) and 0.929 (95% CI: 0.870-0.962), respectively. The SEM and MDC of the TUG were 0.34 and 1.52 seconds, respectively. Large correlations (r > 0.5) were observed between the TUG and the HJHS, SPPB, HEP-Test-Q, and HAL. Regression analysis revealed the HJHS as the sole significant predictor, with the full model explaining 37.0% of the variance in TUG performance.In PwH, the TUG is a reliable test possessing an excellent test-retest and inter-rater reliability, while showing a high validity. TUG times can mainly be predicted by HJHS. The TUG can therefore be considered a suitable tool to evaluate mobility in adult PwH.