Validity of the four-square step test in persons with haemophilia

Recurrent bleeds into joints causes arthropathy leading to pain and reduced joint movement. This may cause a reduction in postural balance and increase the falls risk in patients with haemophilia (PWH). With an ageing PWH population the need to assess functional balance in clinic will be essential to monitor function and implement interventions to help maintain balance and prevent falls.

To assess the utility of the Four-Square Step Test (FSST) in PWH.

80 PWH of all severity types were recruited and underwent a battery of outcome measures: FSST, Timed up & go (TUG), Short performance physical battery (SPPB), Haemophilia Activity List (HAL), ABC confidence questionnaire, and Haemophilia Joint Health score (HJHS). Demographics were collected, together with self-reported falls/trips history.

All 80 participants were able to complete all test measures. Median age 44.5 years. Number of participants reporting falls ranged from 23% in severe to 3% in mild. Recent trips 53% severe to 17% mild. Excellent Inter and intra-reliability, ICC of .981 (CI .953-.992), P < .001 and ICC .989 (.983-.993) P < .001, respectively. Strong correlations between FSST and TUG/ SPPB .753 and -.728, moderate correlation between FSST and ABC/HAL -.484, -.464 P < .01.

FSST is a valid and safe measure to use in PWH. It correlates strongly with other functional measures, has excellent inter and intra rater reliability. FSST correlates with age rather than severity type and provides information to the clinician on the speed/ability to change direction and clear an obstacle. ABC questionnaire was able to differentiate between severities and offers insight into patient confidence to move. SPPB had a ceiling effect with 52/80 scoring 12 and may not be suitable for PWH.