Descriptive Statistics
Ninety-eight participants with idiopathic PD were enrolled in the study, with an average age of 70.6 years (Table 1). Twenty-two percent (22/98) of participants were female. Based on interviews conducted at the beginning of BT, participants self-reported an average of 0.86 ± 3.58 falls per month at baseline.
Table 1
Description of study participants.
|
all
(n = 98)
|
age
|
|
mean (SD)
|
70.6 (7.98)
|
median (q1-q3)
|
71.0 (66.0–77.0)
|
[min, max]
|
[41.0, 89.0]
|
age category
|
|
< 65
|
20 (20.4%)
|
65–75
|
48 (49.0%)
|
> 75
|
30 (30.6%)
|
sex
|
|
male
|
76 (77.6%)
|
female
|
22 (22.4%)
|
pre-BT self-reported average number of falls per month
|
|
mean (SD)
|
0.861 (3.58)
|
median (q1-q3)
|
0.0417 (0-0.167)
|
[min, max]
|
[0, 30.0]
|
The average follow-up interval during BT was 16.0 months (Table 2). During BT, the mean average number of self-reported falls per month per participant decreased from 0.86 ± 3.58 at baseline to 0.11 ± 0.26 during BT. During the COVID-19 lockdown, when BT was paused for an average of 3 months, falls increased from 0.11 ± 0.26 falls per month during the initial BT interval to 0.26 ± 0.48 falls per month. Once BT was resumed post-lockdown, participants reported another decline in falls, from 0.26 ± 0.48 falls per month to 0.14 ± 0.33. Likewise, the average proportion of months in which at least one fall was reported increased from 8 ± 0.15% during the initial phase of BT, to 12 ± 0.18% during the COVID-19 period, then decreased slightly to 10 ± 0.21% after participants returned to boxing. (Of note, 17 of the original 98 participants did not resume BT after the lockdown.)
Table 2
Summary of falls per study interval.
|
pre-lockdown BT
(n = 98)
|
covid-19 lockdown interval
(no BT)
(n = 98)
|
post-lockdown BT
(n = 81)
|
months of follow-up
|
|
|
|
mean (SD)
|
16.0 (12.2)
|
3.22 (0.697)
|
4.73 (1.00)
|
median (q1-q3)
|
11.0 (8.25–21.8)
|
3.00 (3.00–3.00)
|
5.00 (5.00–5.00)
|
[min, max]
|
[2.00, 50.0]
|
[3.00, 7.00]
|
[1.00, 10.0]
|
average number of falls per month
|
|
|
|
mean (SD)
|
0.109 (0.261)
|
0.255 (0.481)
|
0.143 (0.330)
|
median (q1-q3)
|
0 (0-0.106)
|
0 (0-0.333)
|
0 (0-0.200)
|
[min, max]
|
[0, 1.60]
|
[0, 2.00]
|
[0, 1.50]
|
proportion of months with at least 1 fall
|
|
|
|
mean (SD)
|
0.0764 (0.151)
|
0.117 (0.182)
|
0.102 (0.207)
|
median (q1-q3)
|
0 (0-0.0890)
|
0 (0-0.333)
|
0 (0-0.200)
|
[min, max]
|
[0, 0.875]
|
[0, 0.800]
|
[0, 1.00]
|
Seventeen of the original 98 participants did not resume BT after the lockdown.
Modeling Falls
Over 2,094 aggregate months of data, 175 falls were self-reported (8% of all participant-months). After adjusting for average self-reported number of falls per month prior to BT, there did not appear to be a significant change in relative risk of falling over time during the initial BT interval (RR: 1.01, 95% CI (0.99, 1.03), P = 0.3050) (Table 3, Fig. 1, and Supplemental Table 1). From the beginning of the lockdown to the resumption of BT, the relative risk of falling increased by 51% each month (RRL 1.5058, 95% CI (1.26, 1.79), P < 0001). Once BT was resumed after the lockdown, the risk of falling decreased 20% each month (RR: 0.7992, 95% CI (0.68, 0.95), P = 0.0093); this was a 21% (RR: 0.79, 95% CI (0.67, 0.94), P = 0.0071) decrease in change in relative risk per month (i.e., slope) from the initial BT period and a 47% (RR: 0.53, 95% CI (0.41, 0.68), P < 0.001) decrease from the COVID-19 lockdown interval.
Table 3
Modelling risk of falling at least once, contrast estimates.
time period
|
change in risk over time
|
estimate
|
95% confidence interval
|
P
|
BT
|
1.0115
|
0.9897
|
1.0337
|
0.3050
|
lockdown
|
1.5058
|
1.2614
|
1.7975
|
< 0.0001
|
return
|
0.7992
|
0.6750
|
0.9462
|
0.0093
|
lockdown vs BT
|
1.4887
|
1.2434
|
1.7825
|
< 0.0001
|
return vs lockdown
|
0.5307
|
0.4148
|
0.6790
|
< 0.0001
|
Modeling was based on the number of months in which at least one fall occurred. Return = post-lockdown resumption of BT.
Similar results as described above were seen when excluding 49 participants who never reported any falls, at any time during the study period (Supplemental Tables 2 and 3).
Sex as a Variable in Falls Reduced by BT
During the monitoring period, 10% (44/404) of female visits and 7% (131/1690) of male visits recorded a fall. In both males and females, there was no change in falls during the initial BT period or after returning post-lockdown. Similarly, females reported a greater increase in risk of falling per month during the COVID period: 84% increase per month in females (RR: 1.84, 95% CI (1.05, 3.24), P = 0.0318) vs. 49% increase per month in males (RR: 1.49, 95% CI (1.23, 1.81), P < 0.0001) (Table 4). After resuming BT, females experienced a 24% decrease in risk of falling per month (RR: 0.76, 95% CI (0.57, 0.996), P = 0.0471), whereas the decrease in males was not statistically significant (RR: 0.82, 95% CI (0.66, 1.02), P = 0.0718).
Table 4
Sex as a variable in falls during BT, based on number of months in which at least one fall occurred.
|
change in risk over time
|
|
females (n = 22)
|
males (n = 76)
|
interval
|
estimate
|
95% confidence interval
|
P
|
estimate
|
95% confidence interval
|
P
|
BT
|
1.0224
|
0.9842
|
1.0621
|
0.2533
|
1.0103
|
0.9846
|
1.0366
|
0.4375
|
lockdown
|
1.8493
|
1.0549
|
3.2418
|
0.0318
|
1.4930
|
1.2311
|
1.8105
|
< 0.0001
|
return
|
0.7559
|
0.5735
|
0.9964
|
0.0471
|
0.8202
|
0.6611
|
1.0177
|
0.0718
|
lockdown vs BT
|
1.8087
|
1.0532
|
3.1060
|
0.0317
|
1.4778
|
1.2147
|
1.7978
|
< 0.0001
|
return vs lockdown
|
0.4088
|
0.2325
|
0.7186
|
0.0019
|
0.5494
|
0.4082
|
0.7394
|
< 0.0001
|
Return = post-lockdown resumption of BT.
Age as a Variable in Falls Reduced by BT
To assess the effect of age in BT and PD-associated falls, we stratified the cohort into participants < 65 years old (n = 20, 20%), 65–75 years old (n = 48, 49%), and > 75 years old (n = 30, 31%) at the beginning of BT. Among those < 65 years old, 5% of all observations (22/445) reported a fall. This increased to 8% (88/1135) in those 65–75 years of age, and 9% (65/689) in those > 75 years of age. Over the initial course of BT, risk of falls increased by 2% each month for those < 65 years old (RR: 1.02, 95% CI: (1.01, 1.04), P = 0.0048) and > 75 years old (RR: 1.02, 95% CI: (1.00, 1.05), P = 0.0405), but no significant change was observed in participants between 65–75 years (RR: 1.02, 95% CI: (0.98, 1.05), P = 0.2861) (Table 5). During the COVID-19 lockdown, those > 65 years old experienced the greatest increase in the number of falls over time: 85% greater per month in those 65–75 years of age (RR: 1.85, 95% CI: (1.32, 2.59), P = 0.0003) and 59% greater in those greater than 75 years of age (RR: 1.63, 95% CI: (1.24, 2.15), P = 0.0005). There was no significant change in risk of falling in those < 65 years of age during the lockdown (RR: 1.74, 95% CI: (0.92, 3.28), P = 0.0903). As a result, only those 65–75 of age saw a significant reduction in risk of falling per month once BT was re-initiated after lockdown (RR: 0.76, 95% CI: (0.61, 0.93), P = 0.0085).
Table 5
Age as a variable in falls during BT, based on number of months in which at least one fall occurred.
interval
|
change in risk over time
|
< 65 years
|
65–75 years
|
> 75 years
|
estimate
|
95% confidence interval
|
P
|
estimate
|
95% confidence interval
|
P
|
estimate
|
95% confidence interval
|
P
|
BT
|
1.0205
|
1.0062
|
1.0351
|
0.0048
|
1.0186
|
0.9847
|
1.0536
|
0.2861
|
1.0231
|
1.0010
|
1.0457
|
0.0405
|
lockdown
|
1.7353
|
0.9170
|
3.2837
|
0.0903
|
1.8494
|
1.3205
|
2.5903
|
0.0003
|
1.6311
|
1.2402
|
2.1452
|
0.0005
|
return
|
0.6626
|
0.4380
|
1.0021
|
0.0512
|
0.7553
|
0.6128
|
0.9309
|
0.0085
|
0.9374
|
0.6796
|
1.2929
|
0.6934
|
lockdown vs BT
|
1.7004
|
0.8988
|
3.2166
|
0.1027
|
1.8157
|
1.2865
|
2.5626
|
0.0007
|
1.5942
|
1.2111
|
2.0986
|
0.0009
|
return vs lockdown
|
0.3818
|
0.1901
|
0.7670
|
0.0068
|
0.4084
|
0.2713
|
0.6146
|
< 0.0001
|
0.5747
|
0.3747
|
0.8813
|
0.0111
|
Return = post-lockdown resumption of BT.
Performance Metrics
Other performance measures, such as the number of times participants were able to stand from a chair in 15 seconds, stand on each leg for 30 seconds, stand from the floor, walk normally, heel-toe touch, crossover, walk backwards, and, were collected for an average 16 ± 12 months of BT before the lockdown and 5 ± 1 months after resumption of BT. All metrics except standing from a chair and on each leg were semiquantitative, as described in the Methods. The median number of times participants were able to stand from a chair in 15 seconds was 7 times during BT and 8 times after the lockdown when BT resumed (Table 6). During the initial BT interval, participants were able to stand on their right and left leg for 15.7 ± 11.3 and 14.7 ± 10.7 seconds, respectively. During the post-lockdown interval, the average duration increased to 17.1 ± 11.4 and 16.2 ± 10.8 seconds on the right and left leg, respectively.
Table 6
Summary of performance metrics.
|
BT
(n = 98)
|
post-lockdown
(n = 81)
|
all
(n = 179)
|
months of follow-up
|
|
|
|
mean (SD)
|
16.0 (12.2)
|
4.73 (1.00)
|
10.9 (10.7)
|
median (q1-q3)
|
11.0 (8.25–21.8)
|
5.00 (5.00–5.00)
|
5.00 (5.00-11.5)
|
[min, max]
|
[2.00, 50.0]
|
[1.00, 10.0]
|
[1.00, 50.0]
|
average number of falls per month
|
|
|
|
mean (SD)
|
0.109 (0.261)
|
0.143 (0.330)
|
0.124 (0.294)
|
median (q1-q3)
|
0 (0-0.106)
|
0 (0-0.200)
|
0 (0-0.118)
|
[min, max]
|
[0, 1.60]
|
[0, 1.50]
|
[0, 1.60]
|
average stand from chair
|
|
|
|
mean (SD)
|
7.11 (3.47)
|
8.08 (3.97)
|
7.56 (3.73)
|
median (q1-q3)
|
7.25 (5.20–9.29)
|
7.80 (6.23–10.9)
|
7.55 (6.00-9.80)
|
[min, max]
|
[0, 14.0]
|
[0, 17.8]
|
[0, 17.8]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
average stand from floor
|
|
|
|
mean (SD)
|
2.61 (0.580)
|
2.68 (0.589)
|
2.64 (0.584)
|
median (q1-q3)
|
3.00 (2.00–3.00)
|
3.00 (2.78-3.00)
|
3.00 (2.00–3.00)
|
[min, max]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
average normal walk
|
|
|
|
mean (SD)
|
2.99 (0.107)
|
2.98 (0.135)
|
2.98 (0.121)
|
median (q1-q3)
|
3.00 (3.00–3.00)
|
3.00 (3.00–3.00)
|
3.00 (3.00–3.00)
|
[min, max]
|
[2.00, 3.00]
|
[2.00, 3.00]
|
[2.00, 3.00]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
average heel toe touch
|
|
|
|
mean (SD)
|
2.47 (0.565)
|
2.47 (0.574)
|
2.47 (0.568)
|
median (q1-q3)
|
2.60 (2.00–3.00)
|
2.75 (2.00–3.00)
|
2.63 (2.00–3.00)
|
[min, max]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
average crossovers
|
|
|
|
mean (SD)
|
2.41 (0.640)
|
2.49 (0.680)
|
2.45 (0.658)
|
median (q1-q3)
|
2.67 (2.00–3.00)
|
3.00 (2.00–3.00)
|
2.80 (2.00–3.00)
|
[min, max]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
average walk straight line
|
|
|
|
mean (SD)
|
2.69 (0.510)
|
2.70 (0.486)
|
2.69 (0.498)
|
median (q1-q3)
|
3.00 (2.40-3.00)
|
3.00 (2.60-3.00)
|
3.00 (2.50-3.00)
|
[min, max]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
average walk backwards
|
|
|
|
mean (SD)
|
2.82 (0.370)
|
2.77 (0.461)
|
2.80 (0.414)
|
median (q1-q3)
|
3.00 (2.90-3.00)
|
3.00 (2.80-3.00)
|
3.00 (2.80-3.00)
|
[min, max]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
[1.00, 3.00]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
average stand on right leg
|
|
|
|
mean (SD)
|
15.7 (11.3)
|
17.1 (11.4)
|
16.3 (11.3)
|
median (q1-q3)
|
14.5 (4.00-27.1)
|
15.8 (7.20–30.0)
|
15.4 (5.21–29.4)
|
[min, max]
|
[0, 30.0]
|
[0, 30.0]
|
[0, 30.0]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
average stand on left leg
|
|
|
|
mean (SD)
|
14.7 (10.7)
|
16.2 (10.8)
|
15.4 (10.8)
|
median (q1-q3)
|
15.0 (4.30–26.3)
|
16.2 (6.10–27.3)
|
15.3 (4.85–26.6)
|
[min, max]
|
[0, 30.0]
|
[0, 30.0]
|
[0, 30.0]
|
missing
|
11 (11.2%)
|
6 (7.4%)
|
17 (9.5%)
|
SD = standard deviation.
During the initial pre-lockdown BT period, the number of times participants were able to stand upright from a sitting position in a 15-second interval significantly increased over time (IRR: 1.01, 95% CI: (1.00, 1.01), P = 0.0193) (Fig. 2). Likewise, after participants returned to BT post-lockdown, there was another significant improvement each month (IRR: 1.02, 95% CI: (1.01, 1.04), P = 0.0014).
Regarding standing on one leg, of the 1,955 tests performed, 12% (n = 236) resulted in participants able to stand on their right leg for the full 30 seconds and 10% (n = 198) resulted in participants able to stand on their left leg for the full 30 seconds. There was no change in the odds of being able to stand on either leg over time, whether before the COVID-19 lockdown (Right leg RR: 1.01, 95% CI (0.99, 1.03), P = 0.3544; Left leg OR: 1.01, 95% CI: (0.98, 1.03), P = 0.5763) or after (Right leg RR: 1.02, 95% CI (0.96, 1.08), P = 0.5354; Left leg OR: 1.03, 95% CI: (0.96, 1.10), P = 0.4301). Of those that stood for less than 30 seconds, there was not a significant change in number of seconds standing over time on either leg before the lockdown (Right leg IRR: 1.00, 95% CI (0.99, 1.01), P = 0.9733; Left leg IRR: 1.00, 95% CI: (0.99, 1.01), P = 0.8169) (Fig. 2). However, after returning to BT after the lockdown, the average number of seconds standing on the right leg increased by 7% each month (IRR: 1.07, 95% CI: (1.00, 1.13), P = 0.0370). Similarly, the number of seconds standing on the left leg increased by 5% each month following the lockdown (IRR: 1.05, 95% CI: 1.00, 1.10), P = 0.0378).
Across both periods, the median semi-quantitative score that participants were able to stand from the floor, walk normally, heel toe touch, walk straight, or walk backwards was approximately 3/3 (Table 6). Because there was insufficient variance in those semi-quantitatively-scored metrics, no further analysis of those metrics was done.