Four square step test performance in people with Parkinson disease.
OBJECTIVE
The Four Square Step Test (4SST), a quick and simple test of multidirectional stepping, may be useful in predicting falls in people with Parkinson disease (PD). We studied the reliability of the 4SST and its ability to discriminate between freezers and nonfreezers, between fallers and nonfallers, and factors predictive of 4SST performance in people with PD.


METHODS
Fifty-three individuals with idiopathic PD completed the full protocol, including the 4SST as well as measures of balance, walking, and disease severity on anti-PD medication.


RESULTS
Interrater (intraclass correlation coefficient [ICC] = 0.99) and test-retest reliability were high (ICC = 0.78). The median 4SST performance was 9.52 seconds. There was a significant difference between 4SST time on-medication versus off (P = 0.03), while differences between fallers and nonfallers (P = 0.06) and between freezers and nonfreezers (P = 0.08) did not reach significance. All outcome measures were significantly related to 4SST time. In an exploratory, simultaneous regression analysis, 56% of the variance in 4SST performance could be accounted for by 3 measures: Mini-Balance Evaluation Systems Test (Mini-BESTest), Five Time Sit to Stand, and Nine Hole Peg Test. The 4SST cutoff score for distinguishing fallers from nonfallers was 9.68 seconds (Area under curve = 0.65, sensitivity = 0.73, specificity = 0.57). The posttest probability of an individual with a score greater than the cutoff being a faller was 31% (pretest probability = 21%).


CONCLUSIONS
The 4SST is a reliable, quick test that can distinguish between on-and off-medication conditions in PD but is not as good as other tests (eg, Mini-BESTest) for distinguishing between fallers and nonfallers. Video Abstract available (see the Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A31) for more insights from the authors.
Washington University in St. Louis School of Medicine, St. Louis, Missouri 63108, USA.
Ryan P
RP
Duncan
Gammon M
GM
Earhart
D000058:Accidental Falls / Q000517:prevention & control; D000368:Aged; D005080:Exercise Test / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D010300:Parkinson Disease / Q000503:physiopathology*; D004856:Postural Balance / Q000502:physiology; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D013997:Time Factors; D016138:Walking / Q000502:physiology