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Table 3 Mean (95 % CI) measures of sway with significant group differences: eyes closed

From: Detection of postural sway abnormalities by wireless inertial sensors in minimally disabled patients with multiple sclerosis: a case–control study

*Instrumented measure of sway

Group with MS

Control group

Mann–Whitney U (p-value)

AP jerk (m2/s5)

0.274 (0.000–0.609)

0.027 (0.020–0.033)

60 (p < 0.0001)

Horizontal jerk (m2/s5)

5.72 (0.000–12.19)

0.521 (0.413–0.629)

57 (p < 0.0001)

ML jerk (m2/s5)

0.151 (0.000–0.335)

0.0066 (0.0051–0.0082)

33 (p < 0.0001)

Horizontal sway area (m2/s4)

0.146 (0.000–0.317)

0.012 (0.010–0.015)

47 (p < 0.0001)

95 % confidence circle area (m2/s4)

1.533 (0.317–2.749)

0.207 (0.167–0.247)

62 (p < 0.0001)

95 % confidence ellipse area (m2/s4)

1.043 (0.081–2.005)

0.128 (0.101–0.154)

43 (p < 0.0001)

AP root mean square (m/s2)

0.249 (0.175–0.323)

0.129 (0.118–0.140)

68 (p = 0.0002)

Horizontal root mean square (m/s2)

0.291 (0.195–0.388)

0.144 (0.131–0.156)

59 (p < 0.0001)

ML root mean square (m/s2)

0.140 (0.075–0.204)

0.057 (0.047–0.068)

58 (p < 0.0001)

Horizontal mean sway velocity (m/s)

0.689 (0.536–0.841)

0.403 (0.346–0.459)

76 (p = 0.00053)

AP sway radius (m/s2)

0.191 (0.139–0.242)

0.103 (0.094–0.113)

71 (p = 0.00028)

Horizontal sway radius (m/s2)

0.236 (0.166–0.307)

0.122 (0.111–0.133)

56 (p < 0.0001)

ML sway radius (m/s2)

0.101 (0.062–0.140)

0.046 (0.037–0.055)

57 (p < 0.0001)

AP sway path length (m/s2)

16.08 (11.68–20.48)

8.76 (7.82–9.69)

67 (p = 0.00018)

Horizontal sway path length (m/s2)

21.78 (15.52–28.04)

10.74 (9.68–11.81)

51 (p < 0.0001)

ML sway path length (m/s2)

11.28 (7.89–14.67)

4.54 (4.01–5.08)

30 (p < 0.0001)

AP range of acceleration (m/s2)

1.469 (0.928–2.011)

0.693 (0.636–0.751)

66 (p = 0.00016)

Horizontal range of acceleration (m/s2)

1.768 (1.020–2.516)

0.769 (0.705–0.834)

51 (p < 0.0001)

ML range of acceleration (m/s2)

0.928 (0.405–1.452)

0.307 (0.258–0.356)

48 (p < 0.0001)

AP total spectral power (m2/s4)

31.63 (7.17–56.10)

4.14 (3.42–4.85)

69 (p = 0.00023)

Horizontal total spectral power (m2/s4)

17.46 (4.57–30.34)

2.40 (2.02–2.78)

48 (p < 0.0001)

ML total spectral power (m2/s4)

12.92 (0.00–28.81)

0.641 (0.504–0.778)

31 (p < 0.0001)

  1. *ML medial-lateral; AP anterior-posterior; units reflect measures are derived from an acceleration signal; significance defined as p < 0.00054 after Bonferroni correction