Despite a similar sex distribution, the age distribution of the 492 nonrespondents was respectively 41, 23, and 36% for those aged 70-74, 75-79, and ≥80 years, significantly differing from that of respondents (chi-square test; p < 0.05). In the 600 respondents who completed the follow-up, the mean baseline age was 76.2 ± 4.6 years with a range of 70–96 years (Table 1). Moreover, 50.8% were females, and 40.7% were afraid of falling. They had 0.1 ± 0.9 ADL difficulty, 0.7 ± 1.5 IADL difficulty, 1.4 ± 1.1 comorbidities, and a mean score of 4.3 ± 3.8 for the GDS, 21.8 ± 7.9 for the MMSE, and 55.4 ±59.3 for the PASE. Among them, 125 were fallers (20.8%), including 73 single fallers and 52 recurrent fallers. Approximately 3% had difficulty in at least one ADL task, and 34% had difficulty in at least one IADL task. Furthermore, 35% had depressive symptoms, 41% had either cognitive impairment or fear of falling, and approximately 65% had a moderate to high PASE score. Moreover, approximately 60% had 1–2 comorbidities, and 15% had three comorbidities, with the following rankings according to prevalence (not shown in the table): cataract (47.8%), hypertension (38.8%), heart diseases (14.2%), respiratory diseases (13.0%), diabetes (11.7%), gout (7.2%), and stroke (4.5%).
Table 1
Distribution of the characteristics of participants and prevalence according to the fall category.
Selected variables
|
Total (N = 600)
|
Prevalence by fall category (%)
|
P-value
|
M ± SD/n
|
%
|
RF (N = 52)
|
OF (N = 73)
|
NF (N = 475)
|
Age (years) #
|
76.2 ± 4.6
|
|
|
|
|
|
70–74
|
264
|
44.0
|
7.6
|
10.2
|
82.2
|
0.269
|
75–79
|
209
|
34.8
|
7.7
|
14.4
|
78.0
|
|
80+
|
127
|
21.2
|
12.6
|
12.6
|
74.8
|
|
Sex#
|
|
|
|
|
|
|
Male
|
295
|
49.2
|
5.8
|
8.5
|
85.8
|
<0.001
|
Female
|
305
|
50.8
|
11.5
|
15.7
|
72.8
|
|
No. of ADL difficulties#
|
0.1 ± 0.9
|
|
|
|
|
|
None
|
583
|
97.2
|
8.4
|
12.2
|
79.4
|
0.408
|
≥1
|
17
|
2.8
|
17.7
|
11.8
|
70.6
|
|
No. of IADL difficulties#
|
0.7 ± 1.5
|
|
|
|
|
|
None
|
394
|
65.7
|
6.1
|
11.7
|
82.2
|
0.003
|
1
|
138
|
23.0
|
10.9
|
11.6
|
77.5
|
|
≥2
|
68
|
11.3
|
19.1
|
16.2
|
64.7
|
|
No. of comorbidities
|
1.4 ± 1.1
|
|
|
|
|
|
None
|
153
|
25.5
|
4.6
|
7.8
|
87.6
|
0.004
|
1–2
|
357
|
59.5
|
8.4
|
14.0
|
77.6
|
|
≥3
|
90
|
15.0
|
16.7
|
12.2
|
71.1
|
|
GDS score (if depressive)
|
4.3 ± 3.8
|
|
|
|
|
|
No
|
389
|
64.8
|
6.4
|
9.5
|
84.1
|
<0.001
|
Yes
|
211
|
35.2
|
12.8
|
17.1
|
70.1
|
|
MMSE score (if impaired)
|
21.8 ± 7.9
|
|
|
|
|
|
No
|
350
|
58.3
|
7.7
|
10.9
|
81.4
|
0.272
|
Yes
|
250
|
41.7
|
10.0
|
14.0
|
76.0
|
|
Fear of falling
|
|
|
|
|
|
|
No
|
356
|
59.3
|
5.1
|
10.7
|
84.3
|
<0.001
|
Yes
|
244
|
40.7
|
13.9
|
14.3
|
71.7
|
|
PASE score
|
55.4 ± 59.3
|
|
|
|
|
|
Low
|
210
|
35.0
|
11.9
|
13.3
|
74.8
|
0.095
|
Moderate
|
186
|
31.0
|
8.1
|
14.0
|
78.0
|
|
High
|
204
|
34.0
|
5.9
|
9.3
|
84.8
|
|
Note: RF, recurrent falls; OF, single fall; NF, no falls; M, mean; SD, standard deviation; ADLs, activities of daily living; IADLs, instrumental activities of daily living; GDS, Geriatric Depression Scale; MMSE, Mini-Mental State Examination; PASE, Physical Activity Scale in the Elderly. P-values indicate the difference in variables across the fall category using the chi-square test. Explanatory variables, other than those specified with # sign, were measured in the second-wave survey. |
Bivariate analyses revealed that the characteristics significantly associated with the risk of falls included female gender, a higher number of IADL difficulties, a higher number of comorbidities, depressive symptoms, and fear of falling; however, age, the number of ADL difficulties, cognitive impairment, and physical activity level were not associated with fall risk. In contrast to the prevalence of RF, the prevalence of single fall did not present a smooth gradient of risk by age, the number of ADL difficulties, the number of IADL difficulties, the number of comorbidities, and physical activity level.
Table 2 shows that every mean QOL score significantly varied according to the fall category (ANOVA; p < 0.05), except for the Soc and Env domains. The highest and lowest mean QOL scores were 74.0 and 42.5 for BP and PCS, respectively, in the SF-36, whereas the corresponding mean subscale scores were 13.8 for the Soc domain and 12.9 for the Psy domain in the WHOQOL-BREF. Although both recurrent and single fallers tended to have a lower mean QOL score than non-fallers in most subscales (except for VT, MH, Psy, Soc, and Env), no significant difference was observed between recurrent and single fallers (Scheffé multiple-comparison test; p > 0.05).
Table 2
Mean subscale scores of SF-36 and WHOQOL-BREF by fall category.
Subscale
|
Total
(N = 600)
|
Fall category
|
P-value
|
RF (N = 52)
|
OF (N = 73)
|
NF (N = 475)
|
SF-36
|
|
|
|
|
|
PFa
|
61.7 ± 32.0
|
45.6 ± 29.5
|
46.0 ± 29.8
|
65.8 ± 31.3 a
|
<0.001
|
RP
|
53.8 ± 46.5
|
40.4 ± 46.2
|
30.1 ± 42.5
|
58.8 ± 45.8
|
<0.001
|
BP
|
74.0 ± 25.4
|
60.9 ± 28.4
|
65.5 ± 25.5
|
76.8 ± 24.3
|
<0.001
|
GHb
|
50.8 ± 17.9
|
38.2 ± 17.3 a
|
43.6 ± 17.6
|
53.3 ± 17.1a
|
<0.001
|
VTa
|
65.0 ± 18.9
|
59.8 ± 18.5a
|
59.3 ± 19.1
|
66.4 ± 18.7
|
0.001
|
SF
|
72.5 ± 27.4
|
59.6 ± 29.7
|
62.3 ± 28.0
|
75.4 ± 26.3
|
<0.001
|
RE
|
64.9 ± 45.5
|
48.1 ± 47.3
|
48.9 ± 46.8
|
69.3 ± 44.2
|
0.001
|
MHa
|
72.9 ± 16.3
|
69.3 ± 18.2a
|
68.9 ± 17.5
|
73.9 ± 15.7
|
0.012
|
PCSc
|
42.5 ± 11.7
|
36.2 ± 11.2a
|
36.4 ± 10.9
|
44.1 ± 11.4b
|
<0.001
|
MCSc
|
47.8 ± 11.4
|
44.0 ± 12.2a
|
44.6 ± 12.8
|
48.7 ± 10.9 b
|
<0.001
|
WHOQOL-BREF
|
|
|
|
|
|
Phy
|
13.7 ± 2.9
|
11.9 ± 2.8
|
12.5 ± 2.7
|
14.0 ± 2.8
|
<0.001
|
Psy
|
12.9 ± 2.7
|
11.6 ± 2.9
|
12.5 ± 2.5
|
13.2 ± 2.7
|
<0.001
|
Soca
|
13.8 ± 2.1
|
13.4 ± 2.0
|
13.5 ± 1.7
|
13.8 ± 2.1 a
|
0.150
|
Env
|
13.4 ± 2.5
|
12.8 ± 2.7
|
13.2 ± 2.3
|
13.5 ± 2.5
|
0.131
|
Notes: Mean ± standard deviation is presented for each subscale according to the fall category. PF, physical functioning; RP, role limitations due to physical health problems; BP, bodily pain; GH, general health perceptions; VT, vitality; SF, social functioning; RE, role limitations due to emotional problems; MH, mental health; PCS, physical component summary; MCS, mental component summary; Phy, Physical domain; Psy, Psychological domain; Soc, Social domain; Env, Environmental domain; RF, recurrent falls; OF, single fall; NF, no falls. a = one missing value; b = two missing values; c = three missing values. |
P-values indicate the mean subscale score difference across fall category using one-way analysis of variance. |
Individuals who were more advanced in age, female, with difficulty in at least one ADL/IADL task, with more comorbidities, with depressive symptoms, with cognitive impairment, and with fear of falling tended to have a lower mean QOL score than their counterparts, with only a few exceptions. In contrast, older people who had a high PASE score tended to have a higher mean QOL score, followed by those with a moderate PASE score and those with a low PASE score (Additional file 2: Table S2).
Table 3 shows the results of the hierarchical linear regression models for every QOL subscale. With a sequential entry of fall frequency and sociodemographic, medical, and lifestyle variables, the proportions of the total amount of variance explained gradually increased, and the effect of fall frequency declined in the models after initiation. However, the partial regression coefficients of fall frequency remained significantly negative for GH, PCS, and Phy only in the full models.
Table 3
Associations between fall frequency and every subscale of QOL by hierarchical linear regression models.
Fall frequency
|
SF-36
|
WHOQOL-BREF
|
PF
|
RP
|
BP
|
GH
|
VT
|
SF
|
RE
|
MH
|
PCS
|
MCS
|
PH
|
PS
|
SR
|
EN
|
Model 1
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Fall frequency
|
−4.81***
|
−5.17**
|
−3.51***
|
−3.56***
|
−1.79**
|
−3.75***
|
−5.16**
|
−1.21*
|
−1.89***
|
−1.14**
|
−0.50***
|
−0.32**
|
−0.12
|
−0.10
|
R2
|
0.03
|
0.02
|
0.03
|
0.05
|
0.01
|
0.03
|
0.02
|
0.01
|
0.03
|
0.01
|
0.04
|
0.02
|
0.00
|
0.00
|
Model 2
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Fall frequency
|
−3.55***
|
−3.80*
|
−2.84**
|
−3.20***
|
−1.28
|
−2.81**
|
−3.96*
|
−0.79
|
−1.49***
|
−0.83*
|
−0.42***
|
−0.26*
|
−0.09
|
−0.05
|
R2
|
0.27
|
0.13
|
0.09
|
0.10
|
0.08
|
0.19
|
0.12
|
0.06
|
0.18
|
0.09
|
0.17
|
0.08
|
0.03
|
0.05
|
Model 3
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Fall frequency
|
−1.41
|
−0.94
|
−1.01
|
−1.70**
|
0.30
|
−0.77
|
−0.94
|
0.56
|
−0.72*
|
0.14
|
−0.19**
|
−0.04
|
0.04
|
0.11
|
R2
|
0.52
|
0.35
|
0.35
|
0.41
|
0.47
|
0.51
|
0.36
|
0.41
|
0.43
|
0.49
|
0.55
|
0.52
|
0.30
|
0.38
|
Model 4
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Fall frequency
|
−1.23
|
−0.80
|
−0.94
|
−1.66**
|
0.35
|
−0.66
|
−0.73
|
0.56
|
−0.67*
|
0.17
|
−0.18**
|
-0.04
|
0.03
|
0.11
|
R2
|
0.58
|
0.36
|
0.36
|
0.42
|
0.48
|
0.54
|
0.40
|
0.41
|
0.46
|
0.50
|
0.57
|
0.52
|
0.31
|
0.39
|
Note: * p <.05; **p <.01; ***p <.001. Model 1 was adjusted for fall frequency. Model 2 was adjusted for fall frequency, age, sex, number of ADL difficulty, and number of IADL difficulty. Model 3 was adjusted for Model 2 variables, number of comorbidities, GDS scores, MMSE scores, and fear of falling. Model 4 was adjusted for Model 3 variables, and PASE scores. |
In the final models adjusted for fall category and the selected covariates, the proportions of total QOL variation collectively explained were between 0.5 and 0.7 for PF, SF, and MCS and the Phys and Psy domains and between 0.3 and 0.5 for the other subscales (Table 4). Relative to NF, one unit change in a single fall was significantly associated with losses of 10.28 PF scores, 17.05 RP scores, 4.93 GH scores, 4.62 PCS scores, and 0.65 Phy domain scores, whereas one unit change in RF was associated with losses of 6.17 GH scores and 0.59 Phy domain score.
Table 4
Multiple linear regression models for each subscale of SF-36 and WHOQOL-BREF.
|
PF
|
RP
|
BP
|
GH
|
VT
|
SF
|
RE
|
MH
|
PCS
|
MCS
|
Phy
|
Psy
|
Soc
|
Env
|
Fall category
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
OF vs. NF
|
−10.28***
|
−17.05***
|
−3.93
|
−4.93**
|
−0.67
|
−4.62
|
−7.57
|
0.17
|
−4.62***
|
−0.06
|
−0.65**
|
0.08
|
0.08
|
0.27
|
RF vs. NF
|
−1.86
|
3.22
|
−3.81
|
−6.17**
|
3.85
|
−0.13
|
0.90
|
3.50
|
−1.85
|
1.77
|
−0.59*
|
−0.15
|
0.27
|
0.38
|
Age
|
−0.79***
|
−0.68
|
0.06
|
0.08
|
−0.07
|
−0.26
|
−0.33
|
0.11
|
−0.22*
|
0.02
|
−0.01
|
0.04*
|
0.02
|
−0.02
|
Sex
|
−2.12
|
−1.47
|
−3.51
|
1.78
|
−1.95
|
0.07
|
−3.54
|
−2.81*
|
−0.16
|
−1.36
|
0.29
|
0.37*
|
0.40*
|
0.19
|
No. ADL difficulty
|
−1.19
|
−1.72
|
0.37
|
1.35
|
0.48
|
0.19
|
−2.97
|
1.93**
|
−0.22
|
0.17
|
−0.08
|
0.06
|
0.08
|
0.11
|
No. IADL difficulty
|
−3.23***
|
−1.06
|
0.29
|
−0.37
|
−0.09
|
−2.46***
|
−0.82
|
−0.72
|
−0.53
|
−0.29
|
−0.16*
|
−0.13*
|
−0.06
|
−0.08
|
No. of comorbidities
|
−2.11**
|
-5.48***
|
−2.89***
|
−3.27***
|
−1.03*
|
−2.19**
|
−3.02*
|
−0.96*
|
−1.51***
|
−0.62*
|
-0.27***
|
−0.02
|
−0.04
|
0.07
|
GDS score
|
−2.43***
|
-3.21***
|
−2.36***
|
−1.63***
|
−2.59***
|
−2.86***
|
−4.10***
|
-2.27***
|
−0.76***
|
−1.60***
|
-0.33***
|
−0.39***
|
−0.25***
|
−0.32***
|
MMSE score
|
0.46**
|
1.13***
|
0.32*
|
0.31**
|
0.07
|
0.45***
|
0.52*
|
−0.21*
|
0.30***
|
−0.00
|
0.07***
|
0.03**
|
0.03**
|
0.03*
|
Fear of falling
|
−12.54***
|
−12.33**
|
−7.31***
|
−5.87***
|
−6.64***
|
−8.76***
|
−3.59***
|
-5.74***
|
-3.65***
|
−3.91***
|
-0.95***
|
−1.31***
|
−0.77***
|
−1.15***
|
PASE score
|
0.14***
|
0.11***
|
0.06***
|
0.03*
|
0.04***
|
0.09***
|
0.16***
|
0.00
|
0.04***
|
0.03***
|
0.01***
|
−0.00
|
−0.00**
|
−0.00**
|
Constant
|
142.12***
|
118.32***
|
89.39***
|
54.96***
|
91.11***
|
107.41***
|
117.66***
|
92.13***
|
62.23***
|
60.30***
|
15.35***
|
12.05***
|
13.30***
|
16.81
|
R2
|
0.59
|
0.38
|
0.36
|
0.42
|
0.49
|
0.54
|
0.40
|
0.41
|
0.47
|
0.51
|
0.57
|
0.52
|
0.31
|
0.39
|
F
|
75.28***
|
32.50***
|
30.56***
|
38.50***
|
50.49***
|
63.01***
|
35.95***
|
37.21***
|
47.23***
|
54.4***
|
70.49***
|
58.85***
|
23.86***
|
34.06***
|
Note: Every multiple linear regression model was adjusted for fall category, age, sex, number of ADL difficulty, number of IADL difficulty, number of comorbidities, GDS score, MMSE score, fear of falling, and PASE score. Sex was coded as 1 for male and 2 for female. |
*p <.05; **p <.01; ***p <.001. |
Moreover, age was negatively correlated with PF and PCS only but was positively correlated with the Psy domain (Table 4). Compared with older men, older women were negatively associated with MH but were positively associated with the Psy and Soc domains. The number of IADL difficulties was negatively associated with PF and SF and the Phy and Psy domains. In contrast, the number of ADL difficulties was positively associated with MH. Moreover, every subscale score of the SF-36 revealed a universal negative association with the number of comorbidities, GDS scores, and fear of falling and a universal positive association with MMSE (except for MH and MCS) and PASE scores. Fear of falling had the greatest inverse association with QOL ratings among all covariates. However, for the WHOQOL-BREF, the number of comorbidities was negatively associated with the Phy domain, but not with the other domains. GDS scores were negatively correlated with every QOL score. Despite a positive association with most subscale QOL, PASE scores had a negative association with the Soc and Env domains.