Reliability and concurrent validity of four square step test scores in subjects with chronic stroke: A pilot study

Objectives: To establish (1) the intrarater and interrater reliability of Four Square Step Test (FSST) times in persons with chronic stroke; (2) the concurrent validity of FSST times with standing balance and functional mobility measures; and (3) the FSST cutoff score for distinguishing the differences in dynamic balance performance of persons with chronic stroke from healthy control adults. Design: Cross-sectional study. Setting: University-based rehabilitation center. Participants: Convenience sample of subjects (N=30) consisting of community-dwelling persons with chronic stroke (n=15) and healthy control adults (n=15). Interventions: Not applicable. Main Outcome Measures: FSST scores; balance and functional mobility measured using Berg Balance Scale (BBS) scores; Timed Up & Go (TUG) test scores; and limits of stability (LOS) measured by dynamic posturography. Results: FSST times showed good intrarater reliability, with intraclass correlation coefficients ranging from.82 to.83 and an interrater reliability >.99. An FSST cutoff score of 11 seconds was able to discriminate between healthy adults older than 50 years and persons with stroke (sensitivity, 73.3%; specificity, 93.3%). FSST times were correlated with LOS scores for directional control in the backward direction (r=.64; P=.01). FSST was approaching a significant correlation with TUG scores (r=.59; P=.02) and LOS scores for endpoint excursion in the forward direction (r=-.58; P=.02). However, there was no correlation with BBS scores. Conclusion: FSST is an easy-to-administer clinical test with good intrarater and interrater reliability in persons with chronic stroke to assess dynamic standing balance. FSST times of 11 seconds are able to differentiate between persons with chronic stroke and healthy adults older than 50 years. The correlation of FSST times with standing balance and functional mobility measures requires further research with a larger sample size.