Journal of Rehabilitation Medicine 51-1CompleteIssue | Page 76

Unstable board balance test for fall identification
finger along the tape measure was recorded. Subjects were then
instructed to reach as far forward as possible, without taking a
step, and the location of the tip of the third finger was recorded
at the furthest distance reached to. The distance between the 2
marks was recorded as the functional reach distance (cm). Each
subject completed 2 trials, with the maximum FRT distance
obtained using in the analysis. The criterion validity, predic-
tive validity, test-retest reliability, and inter-rater reliability
for the FRT, for younger and older adults, has been described
previously (18, 19).
Timed Up and Go (TUG). The following instructions were
provided to subjects: “When I say ‘go’, stand up from the chair
using the armrest, walk 3 m, straight ahead, at a comfortable
speed, up to the cone, turn and return to the chair, and sit down.
I will record the time taken for you to complete the task, from
the time you stand up from the chair to when you return to
a sitting position.” Subjects completed 1 practice trial, with
feedback provided as needed, and subsequently performed the
actual TUG for recording. The time to complete the TUG was
measured using a stopwatch, and one examiner performed all
assessments. High inter- and intra-examiner reliability were
previously reported for the TUG in elderly individuals (20). In
addition, the TUG has concurrent validity with gait speed, the
BBS, and the Barthel Index (20).
Recent fall history. For the purpose of this study, a “fall” was
defined as “an unexpected event in which the subject came to
rest on the ground, floor or a lower level” (21). Subjects were
asked to report the number of falls they had experienced over the
previous year. We excluded falls resulting from extraordinary
environmental factors.
Statistical analysis
For analysis, subjects were divided in a “faller” and “non-
faller” group, according to their self-reported falls history.
Demographic, personal and performance scores were compared
between the 2 groups, using a χ 2 test for the categorical variable
(sex) and an independent sample t-test for continuous variables.
Subsequently, subjects in the faller group were matched 1:1 to
subjects in the non-faller group for sex, age (± 5 years), height
(± 5.9 cm for men and ± 5.1 cm for women) years, and body
weight (± 7.5 kg for men and ± 6.8 kg for women), to control
for the effects of these variables on test scores. The allowed
ranges were defined based on known standard deviations for
men and women, 70–74 years of age, published by The Ministry
of Education, Science, Sports and Culture of Japan (22).
For each performance test, a receiver operating characteristic
(ROC) curve was calculated and the area under the curve (AUC)
used to determine the accuracy of the test in differentiating
fallers from non-fallers, with the AUC interpreted as follows:
AUC ≥ 0.9, high accuracy; AUC between 0.7 and 0.9, moderate
accuracy; and AUC between 0.5 and 0.7, low accuracy (23).
The optimal cut-off value to differentiate between the 2 groups
was calculated for each performance test using Youden’s index.
The sensitivity, specificity, positive likelihood ratio (PLR), and
negative likelihood ratio (NLR) for identified cut-off values
were calculated to determine the discrimination precision for
each performance test with regard to fall history, with a PLR
> 5 and NLR < 0.2 indicating that the test would be clinically
useful, having a high probability of correctly identifying subjects
with and without history of falls (24).
All analyses were performed using IBM SPSS Statistics
software (version 24), with significance level p < 0.05.
73
Table I. Subjects’ characteristics
Variable
Age, years
Sex, female/male
Height, cm
Weight, kg
MMSE
MLSI, °
FRT, cm
TUG, s
Recent fall
Mean (SD)
n
70.6 (3.6)
Range (min–max)
14.0 (65.0–79.0)
23/38
161.1 (8.8) 42.0 (141.5–183.5)
60.5 (11.8) 56.5 (39.5–96.0)
28.6 (1.8)
6.0 (24.0–30.0)
8.3 (0.7)
4.9 (6.1–11.0)
30.1 (4.1) 17.0 (20.5–37.5)
8.4 (1.0)
4.3 (7.0–11.3)
9
Sex was compared between the 2 groups using a χ 2 test, with an independent
t-test used for other variables.
SD: standard deviation; MMSE: Mini Mental State Examination; MLSI: Medial-
Lateral Stability Index, FRT: Functional Reach Test, TUG: Timed Up and Go.
RESULTS
Of the 66 subjects who satisfied the inclusion criteria,
2 were subsequently excluded because of a diagnosis
of knee osteoarthritis, 2 because of an acute onset back
pain, and 1 who had undergone total knee replacement
with the previous year. The demographic and personal
attributes of the 61 subjects included in the analysis,
as well as their performance scores are summarized in
Table I, with between-group differences on measured
variables reported in Table II. The faller and non-faller
groups were comparable with regard to the distribution
of age and body weight, but with a greater proportion of
women in the faller than non-faller group (p = 0.007);
and, with a greater proportion of men, subjects in the
non-faller group were taller than those in the faller
group (p = 0.045). The MLSI was significantly larger
for the faller than non-faller group (p = 0.040, Cohen’s
d = 1.363), but with no between-group difference
for the FRT (p = 0.168, Cohen’s d = 0.512) or TUG
(p = 0.492, Cohen’s d = 0.254).
Between-group differences on the balance perfor-
mance tests, after matching between the faller and
non-faller groups, are reported in Table III. During
the matching process, one subject was excluded from
the faller group because a matched control in the
non-faller group could not be identified; data for 8
subjects in the faller group and 8 in the non-faller group
were included in the analysis. Even after matching, a
Table II. Comparison of variables between the faller and non-
faller group (n  = 61)
Faller
(n  = 9)
Age, years, mean (SD)
Sex, female, n
Height, cm, mean (SD)
Weight, kg, mean (SD)
MLSI, °, mean (SD)
FRT, cm, mean (SD)
TUG, s, mean (SD)
Non-faller
(n  = 52)
70.4 (3.6)
70.7 (3.6)
7
16
155.7 (8.3)
162.0 (8.6)
57.1 (14.3)
61.1 (11.3)
9.0 (1.0)
8.2 (0.5)
30.4 (4.5)
28.3 (4.0)
8.4 (0.8)
8.2 (1.0)
p-value Cohen’s d
0.861
0.007
0.045
0.351
0.040
0.168
0.492
0.065
0.750
0.345
1.363
0.512
0.254
MLSI: Medial-Lateral Stability Index, FRT: Functional Reach Test, TUG: Timed
Up and Go. Sex was compared between the 2 groups using a χ2 test, with an
independent t-test used for other variables.
J Rehabil Med 51, 2019