JAMDA xxx (2015) 1e7
JAMDA journal homepage: www.jamda.com
Original Study
Impact of Tai-Chi on Falls Among Preclinically Disabled Older People. A Randomized Controlled Trial Lesley Day BSc (Hons), MPH, PhD a, *, Keith D. Hill Grad Dip Physio, BAppSc (Physio), PhD b, *, Voula Z. Stathakis BSc, Grad Dip Epi and Biostat, MPH a, Leon Flicker MBBS, FRACP, PhD c, Leonie Segal BEcon (Hons), MEcon, PhD d, Flavia Cicuttini MBBS, FRACP, PhD e, Damien Jolley BSc (Hons), Dip Ed, MSc (Epi), MSc (Stat) e a
Falls Prevention Research Unit, Monash Injury Research Institute, Monash University, Melbourne, Australia Faculty of Health Sciences, School of Physiotherapy and Exercise Science, Curtin University, Perth, Australia Center for Medical Research, University of Western Australia, Perth, Australia d Division of Health Sciences, School of Population Health, University of South Australia, Adelaide, Australia e Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia b c
a b s t r a c t Keywords: Falls tai-chi older people
Objective: To investigate the effectiveness of tai-chi in preventing falls among community-dwelling older people. Design: Multisite parallel group individually randomized controlled trial. Setting: Melbourne, Australia. Participants: Preclinically disabled community-dwelling people 70 þ years (n ¼ 503), without major medical conditions or moderate to severe cognitive impairment. Intervention: Sixty-minute modified Sun style tai-chi group-based exercise program twice weekly for 48 weeks; control intervention was a seated group-based flexibility exercise program of the same dose. Measurements: All falls, self-reported using a monthly calendar, analyzed at 24 weeks and 48 weeks. Injurious falls reported in follow-up telephone interviews for each reported fall. Results: The adjusted fall incidence rate ratios at 24 and 48 weeks were 1.08 [(95% confidence interval (CI) 0.64e1.81)], and 1.12 (95% CI 0.75e1.67), respectively. A higher proportion of intervention participants ceased attendance in the first 24 weeks (difference 17.9%, 95% CI 9.6e25.8), and the second 24 weeks (2.7%, 95% CI 5.0 to 10.4). Intervention participants who ceased attendance had lower left quadriceps strength (difference 3.3 kg 95% CI 0.15e6.36) and required longer to complete the timed up and go test (difference 1.7 seconds 95% CI 0.22e3.17) at baseline. Conclusions: This study does not support modified Sun style tai-chi as a falls prevention measure among relatively well community-dwelling older people with modified mobility and at increased risk of disability. Insufficient intervention intensity, or low exercise class attendance may have contributed to the lack of effect, as may have attrition bias among the intervention group. Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine.
This study was funded by the Australian National Health and Medical Research Council (Senior Research Fellowship ID236880, Project Grant ID 384103). Trial Registration: Australian Clinical Trials Register ACTRN01206000431527. The authors declare no conflicts of interest. The Australian National Health and Medical Research Council played no role in the study or in the decision to submit the manuscript for publication. * Address correspondence to Lesley Day, BSc (Hons), MPH, PhD, Monash Injury Research Institute, Monash University, 21 Alliance Lane, Wellington Road, Melbourne, VIC 3800, Australia or Keith D. Hill, Grad Dip Physio, BAppSc (Physio), PhD, School of Physiotherapy and Exercise Science, GPO Box U1987, Perth, Western Australia 6845, Australia. E-mail addresses: [email protected] (L. Day), [email protected] (K.D. Hill). http://dx.doi.org/10.1016/j.jamda.2015.01.089 1525-8610/Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine.
Within the Nagi model of disability, falls among older people may signal underlying pathology which manifests as impairment (ie, dysfunction and structural abnormalities of body systems).1 There are a number of physiological changes associated with aging as well as specific diseases that are well established risk factors for falls.2 These factors and diseases are associated with dysfunction in musculoskeletal, cardiovascular, and neurologic systems in particular. The resulting falls represent an impairment in function at the level of the whole person and can lead to death and disability by resulting injury and/or activity limitation associated with fear of subsequent falls.2e5 Given the relatively high incidence of falls among older people, the
2
L. Day et al. / JAMDA xxx (2015) 1e7
resulting burden on health and residential care systems, and global population aging, reducing falls is an important population health imperative.6 Balance enhancing exercise can prevent falls among older people7,8 and may also avert or delay physical disability at least for those who are already physically frail.9e12 Exercise has also been shown to preserve cognitive function.13 Tai-chi is an increasingly popular exercise that integrates balance postural alignment, trunk rotation, weight-shift transitions, and strengthening.14 These are all attributes that are postulated to prevent or slow the development of physical disability.15 There is emerging evidence that tai-chi may also slow cognitive decline.13 Tai-chi, therefore, is a promising moderator of disability and has been shown to prevent falls among communitydwelling older people.7 We undertook the Exercise for Independent Living trial to test the effect of tai-chi on physical disability moderation, and on falls outcomes, among preclinically disabled community-dwelling older people, which is a group not yet actually physically disabled but who have modified some mobility tasks and are at increased risk of disability.16 We have previously reported the disability outcomes,17 and here we report the falls outcome. The effectiveness of tai-chi in reducing falls among less physically able older people has not been comprehensively examined. Two studies have demonstrated potential for falls reduction among transitionally frail and frail community dwelling older people, defined by different frailty definitions.18,19 Methods Design and Participants We conducted a multisite parallel group randomized controlled trial (individual randomization 1:1). Participants were 70 years and over, community residents in Melbourne (Australia), and preclinically disabled defined by self-reported difficulty with, or modification of, 2 mobility tasks (walking and climbing stairs).16 Falls history was not a selection criteria, unlike many falls prevention trials. Participants resided either in the community or in retirement villages. Details of the design, exclusion criteria and methods have been reported elsewhere.17,20 The Monash University Human Research Ethics Committee approved the study. We undertook recruitment within the locality of the selected exercise class venues from May 2006 to February 2008. Venues were in either community facilities or retirement villages. Invitation letters were sent to 14,358 people 70 years and over registered on the Australian electoral roll (95% of people 70 years and over are registered).21,22 Interested people were screened for eligibility by telephone. Participants were randomized by the study statistician (D.J.) using a computerized random number generator, and a minimization algorithm. The allocation list was e-mailed directly to the exercise program administrator who managed exercise class delivery, independent of the data collectors. Interventions The intervention program was modified Sun style tai-chi (46 forms, which is a series of whole body movements performed continuously) and covered agility, mobility, balance, strength, breathing, and relaxation.23 This program is widely promoted in the United States and Australia, being endorsed by the respective arthritis foundations.24,25 Sun style tai-chi has been shown to improve knee and ankle flexor and extensor muscle strength, flexibility, and mobility among older people in residential care,14 knee extensor endurance among community dwelling older women with osteoarthritis,26 balance following a stroke,27 both static and dynamic
balance among community dwelling older people,28 and reduce falls among community dwelling older people.28 The curriculum covered the 6 basic (and reverse), the 6 advanced (and reverse) movements of part I and 1 section of the 11 movements of part II in the first 24 weeks (35 of the 46 Forms). In the second 24 weeks, the remaining part II movements were covered in addition to increased focus on the concept of flow.23 New movements were introduced at intervals specified in the curriculum with some classes devoted to practice and consolidation. Classes were delivered by qualified leaders who practiced together prior to commencement. The control group received a flexibility and stretching program, conducted primarily in the seated position. Exercises included flexion, extension, and rotation of the trunk and all the major joints. Calf stretching and hip extension, abduction, and adduction were performed standing, holding on to the back of a chair. This program would not be expected to affect falls risk, given the lack of balance challenge.8 Exercises were introduced gradually over the first 24 weeks and combined in a rolling curriculum to avoid constant repetition. Classes were delivered by qualified and experienced exercise leaders trained in this program by an experienced physiotherapist (K.H.). Classes of 12e16 participants were held twice weekly for 60 minutes per class, for up to 48 weeks. Toward the end of the first 24 weeks, participants were invited to continue for a second 24 weeks. Thus, the longest possible period for class delivery was 48 weeks. We were unable to offer the second 24 week term to 37 intervention and 23 control participants (Figure 1) because of budget limitations. All sessions included a warm up and cool down. We undertook visits within the first 2 to 4 weeks of each class to observe program fidelity, and feedback was provided if necessary. Participants paid $AUD3 per class. Leaders recorded weekly attendance and followed up on unplanned absences. Falls Outcome Measures Falls were defined as “unintentionally coming to rest on the ground, floor, or other lower level.”29 Participants reported falls for up to 48 weeks using a monthly post-card calendar system, supplemented with telephone follow up for missing calendars. Reported falls were followed up with a telephone interview to record the circumstances of the fall and any resulting injuries and subsequent treatment. Interviews were completed for 96.3% of reported falls. The interviewer was blind to group assignment. Injurious falls were those resulting in grazes, lacerations, bruising, strains, sprains, fractures, or any other injury. Other Measures Demographic data, medical history, and falls occurrence in the previous 12 months were collected at baseline by a self-report mailed questionnaire completed while the participant was blind to group assignment (before group allocation). Self-reported disability, and objectively measured musculoskeletal and cardiovascular impairment, and functional limitations were recorded by trained staff in a community venue and have been reported elsewhere.17 Analyses The primary outcome was all falls reported from intervention commencement until participants discontinued calendar return or completed the intervention period. Participants who stopped attending in the exercise programs were encouraged to continue using the calendars to report falls. Multiple falls were included and participants had variable follow-up times depending on when falls
L. Day et al. / JAMDA xxx (2015) 1e7
3
Received posted invitation letter (n=14,358) Attended information session (n=354) Did not respond (n=13,475)
Enrollment Assessed for eligibility (n=1237)
Excluded (n=734) Not meeting inclusion criteria (n=583) Eligible, excess to requirements (n=151)
Randomized (n=503)
Allocation
Allocated to control/intervention Received allocation Did not receive allocation Did not start program Received other
Control
Intervention
(n=253) (n=227) (n=25) =23 =2
(n=250) (n=221) (n=29) =28 =1
Follow-Up Control
Intervention
Discontinued intervention 24 weeks Class cancelled Deceased Health issues Schedule issues Didn’t like Other
(n=64) =0 =3 =16 =5 =10 =30
(n=108) =5 =0 =34 =5 =9 =55
Discontinued intervention 25-48 weeks Second 24 wk term not offered Class cancelled Deceased Health issues Schedule issues Didn’t like Other
(n=65) =23 =0 =1 =11 =16 =3 =11
(n=71) =37 =18 =1 =5 =3 =2 =5
=48 =181 =165
=46 =178 =154
Control (n=205)
Intervention (n=204)
=48
=46
(n=205)
(n=204)
=48 =23
=46 =37
Falls surveillance* Refused calendars (all) Complete all months first 24 wks Complete all months full 48 wks
Analyzed first 24 weeks Excluded from analysis No falls surveillance
Analysis
Analyzed full 48 weeks Excluded from analysis No falls surveillance Part 2 not offered *Some parcipants completed calendars aer disconnuing intervenon
Fig. 1. Participant flow chart: Exercise for Independent Living Trial, Melbourne, Australia.
surveillance ceased. We used negative binomial regression models to compare the number of falls in the 2 groups. These models assume a Poisson distribution, allowing for overdispersion, and included the number of falls and the variable follow-up times. However, we used Poisson regression models to compare the number of injurious falls in the 2 groups as model testing indicated that the overdispersion parameter was equal to zero and, therefore, was a better fit for this data subset than the negative binomial. Falls outcomes were analyzed at 2 time points: from commencement to the end of the first 24 weeks, and from commencement to the end of 48 weeks.
We assessed the influence of minor baseline differences in strong falls risk factors by comparing results with and without adjustment.30 Risk factors were retained in the adjusted model if there was a change of 5% or more in the intervention effect. The stratification factor (type of residence) was included in the adjusted model. Interaction terms for the participant’s assigned group and average level of attendance were tested and excluded on the basis of there being no statistically significant interactions present at either time point. Because of variable class attendance and the high proportion of intervention participants who ceased attending the exercise classes,
4
L. Day et al. / JAMDA xxx (2015) 1e7
Table 1 Baseline Characteristics of Participants With Falls Surveillance Data: Exercise for Independent Living Trial, Melbourne, Australia Characteristic
Control n ¼ 205 n
Age groups 70e74 years 75e79 years 80e84 years 85 years Gender Female Type of residence Retirement village Community-dwelling Fall history Fallen previous 12 months Fall related hospital admission previous 12 months Currently taking prescription medication Diabetes Arthritis Age (years) Strength and balance Quadriceps strength right (k) Quadriceps strength left (k) Postural sway eyes open (log mm2) Postural sway eyes closed (log mm2) Timed up and go (seconds) Timed chair stands (seconds) Step test right (steps) Step test left (steps) Berg Balance Scale (score) Beck Depression Inventory score Body mass index
Intervention n ¼ 204 %
n
%
64 64 56 21
31.2 31.2 27.3 10.2
69 62 50 23
33.8 30.4 24.5 11.3
143
69.8
142
69.6
46 158
22.4 77.1
44 160
21.6 78.4
61 6 183 25 122 Mean
29.8 2.9 89.3 12.2 59.5 SD
59 10 190 17 125 Mean
28.9 4.9 93.1 8.3 61.3 SD
77.8
5.0
77.6
5.1
19.9 20.2 5.5 6.0 10.1 9.3 12.4 12.5 7.5 7.0 27.9
8.4 8.8 0.9 0.9 7.5 5.1 3.6 3.6 1.3 5.4 4.8
19.4 19.4 5.6 6.0 10.1 9.7 12.1 12.3 7.7 7.1 27.3
8.3 8.4 0.8 0.9 7.5 5.6 3.4 3.5 0.9 4.8 3.9
we examined fall rates at different levels of adherence. Average weekly attendance levels were calculated for each group for the first 24- and full 48-week periods and stratified into 3 categories (
JAMDA journal homepage: www.jamda.com
Original Study
Impact of Tai-Chi on Falls Among Preclinically Disabled Older People. A Randomized Controlled Trial Lesley Day BSc (Hons), MPH, PhD a, *, Keith D. Hill Grad Dip Physio, BAppSc (Physio), PhD b, *, Voula Z. Stathakis BSc, Grad Dip Epi and Biostat, MPH a, Leon Flicker MBBS, FRACP, PhD c, Leonie Segal BEcon (Hons), MEcon, PhD d, Flavia Cicuttini MBBS, FRACP, PhD e, Damien Jolley BSc (Hons), Dip Ed, MSc (Epi), MSc (Stat) e a
Falls Prevention Research Unit, Monash Injury Research Institute, Monash University, Melbourne, Australia Faculty of Health Sciences, School of Physiotherapy and Exercise Science, Curtin University, Perth, Australia Center for Medical Research, University of Western Australia, Perth, Australia d Division of Health Sciences, School of Population Health, University of South Australia, Adelaide, Australia e Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia b c
a b s t r a c t Keywords: Falls tai-chi older people
Objective: To investigate the effectiveness of tai-chi in preventing falls among community-dwelling older people. Design: Multisite parallel group individually randomized controlled trial. Setting: Melbourne, Australia. Participants: Preclinically disabled community-dwelling people 70 þ years (n ¼ 503), without major medical conditions or moderate to severe cognitive impairment. Intervention: Sixty-minute modified Sun style tai-chi group-based exercise program twice weekly for 48 weeks; control intervention was a seated group-based flexibility exercise program of the same dose. Measurements: All falls, self-reported using a monthly calendar, analyzed at 24 weeks and 48 weeks. Injurious falls reported in follow-up telephone interviews for each reported fall. Results: The adjusted fall incidence rate ratios at 24 and 48 weeks were 1.08 [(95% confidence interval (CI) 0.64e1.81)], and 1.12 (95% CI 0.75e1.67), respectively. A higher proportion of intervention participants ceased attendance in the first 24 weeks (difference 17.9%, 95% CI 9.6e25.8), and the second 24 weeks (2.7%, 95% CI 5.0 to 10.4). Intervention participants who ceased attendance had lower left quadriceps strength (difference 3.3 kg 95% CI 0.15e6.36) and required longer to complete the timed up and go test (difference 1.7 seconds 95% CI 0.22e3.17) at baseline. Conclusions: This study does not support modified Sun style tai-chi as a falls prevention measure among relatively well community-dwelling older people with modified mobility and at increased risk of disability. Insufficient intervention intensity, or low exercise class attendance may have contributed to the lack of effect, as may have attrition bias among the intervention group. Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine.
This study was funded by the Australian National Health and Medical Research Council (Senior Research Fellowship ID236880, Project Grant ID 384103). Trial Registration: Australian Clinical Trials Register ACTRN01206000431527. The authors declare no conflicts of interest. The Australian National Health and Medical Research Council played no role in the study or in the decision to submit the manuscript for publication. * Address correspondence to Lesley Day, BSc (Hons), MPH, PhD, Monash Injury Research Institute, Monash University, 21 Alliance Lane, Wellington Road, Melbourne, VIC 3800, Australia or Keith D. Hill, Grad Dip Physio, BAppSc (Physio), PhD, School of Physiotherapy and Exercise Science, GPO Box U1987, Perth, Western Australia 6845, Australia. E-mail addresses: [email protected] (L. Day), [email protected] (K.D. Hill). http://dx.doi.org/10.1016/j.jamda.2015.01.089 1525-8610/Ó 2015 AMDA e The Society for Post-Acute and Long-Term Care Medicine.
Within the Nagi model of disability, falls among older people may signal underlying pathology which manifests as impairment (ie, dysfunction and structural abnormalities of body systems).1 There are a number of physiological changes associated with aging as well as specific diseases that are well established risk factors for falls.2 These factors and diseases are associated with dysfunction in musculoskeletal, cardiovascular, and neurologic systems in particular. The resulting falls represent an impairment in function at the level of the whole person and can lead to death and disability by resulting injury and/or activity limitation associated with fear of subsequent falls.2e5 Given the relatively high incidence of falls among older people, the
2
L. Day et al. / JAMDA xxx (2015) 1e7
resulting burden on health and residential care systems, and global population aging, reducing falls is an important population health imperative.6 Balance enhancing exercise can prevent falls among older people7,8 and may also avert or delay physical disability at least for those who are already physically frail.9e12 Exercise has also been shown to preserve cognitive function.13 Tai-chi is an increasingly popular exercise that integrates balance postural alignment, trunk rotation, weight-shift transitions, and strengthening.14 These are all attributes that are postulated to prevent or slow the development of physical disability.15 There is emerging evidence that tai-chi may also slow cognitive decline.13 Tai-chi, therefore, is a promising moderator of disability and has been shown to prevent falls among communitydwelling older people.7 We undertook the Exercise for Independent Living trial to test the effect of tai-chi on physical disability moderation, and on falls outcomes, among preclinically disabled community-dwelling older people, which is a group not yet actually physically disabled but who have modified some mobility tasks and are at increased risk of disability.16 We have previously reported the disability outcomes,17 and here we report the falls outcome. The effectiveness of tai-chi in reducing falls among less physically able older people has not been comprehensively examined. Two studies have demonstrated potential for falls reduction among transitionally frail and frail community dwelling older people, defined by different frailty definitions.18,19 Methods Design and Participants We conducted a multisite parallel group randomized controlled trial (individual randomization 1:1). Participants were 70 years and over, community residents in Melbourne (Australia), and preclinically disabled defined by self-reported difficulty with, or modification of, 2 mobility tasks (walking and climbing stairs).16 Falls history was not a selection criteria, unlike many falls prevention trials. Participants resided either in the community or in retirement villages. Details of the design, exclusion criteria and methods have been reported elsewhere.17,20 The Monash University Human Research Ethics Committee approved the study. We undertook recruitment within the locality of the selected exercise class venues from May 2006 to February 2008. Venues were in either community facilities or retirement villages. Invitation letters were sent to 14,358 people 70 years and over registered on the Australian electoral roll (95% of people 70 years and over are registered).21,22 Interested people were screened for eligibility by telephone. Participants were randomized by the study statistician (D.J.) using a computerized random number generator, and a minimization algorithm. The allocation list was e-mailed directly to the exercise program administrator who managed exercise class delivery, independent of the data collectors. Interventions The intervention program was modified Sun style tai-chi (46 forms, which is a series of whole body movements performed continuously) and covered agility, mobility, balance, strength, breathing, and relaxation.23 This program is widely promoted in the United States and Australia, being endorsed by the respective arthritis foundations.24,25 Sun style tai-chi has been shown to improve knee and ankle flexor and extensor muscle strength, flexibility, and mobility among older people in residential care,14 knee extensor endurance among community dwelling older women with osteoarthritis,26 balance following a stroke,27 both static and dynamic
balance among community dwelling older people,28 and reduce falls among community dwelling older people.28 The curriculum covered the 6 basic (and reverse), the 6 advanced (and reverse) movements of part I and 1 section of the 11 movements of part II in the first 24 weeks (35 of the 46 Forms). In the second 24 weeks, the remaining part II movements were covered in addition to increased focus on the concept of flow.23 New movements were introduced at intervals specified in the curriculum with some classes devoted to practice and consolidation. Classes were delivered by qualified leaders who practiced together prior to commencement. The control group received a flexibility and stretching program, conducted primarily in the seated position. Exercises included flexion, extension, and rotation of the trunk and all the major joints. Calf stretching and hip extension, abduction, and adduction were performed standing, holding on to the back of a chair. This program would not be expected to affect falls risk, given the lack of balance challenge.8 Exercises were introduced gradually over the first 24 weeks and combined in a rolling curriculum to avoid constant repetition. Classes were delivered by qualified and experienced exercise leaders trained in this program by an experienced physiotherapist (K.H.). Classes of 12e16 participants were held twice weekly for 60 minutes per class, for up to 48 weeks. Toward the end of the first 24 weeks, participants were invited to continue for a second 24 weeks. Thus, the longest possible period for class delivery was 48 weeks. We were unable to offer the second 24 week term to 37 intervention and 23 control participants (Figure 1) because of budget limitations. All sessions included a warm up and cool down. We undertook visits within the first 2 to 4 weeks of each class to observe program fidelity, and feedback was provided if necessary. Participants paid $AUD3 per class. Leaders recorded weekly attendance and followed up on unplanned absences. Falls Outcome Measures Falls were defined as “unintentionally coming to rest on the ground, floor, or other lower level.”29 Participants reported falls for up to 48 weeks using a monthly post-card calendar system, supplemented with telephone follow up for missing calendars. Reported falls were followed up with a telephone interview to record the circumstances of the fall and any resulting injuries and subsequent treatment. Interviews were completed for 96.3% of reported falls. The interviewer was blind to group assignment. Injurious falls were those resulting in grazes, lacerations, bruising, strains, sprains, fractures, or any other injury. Other Measures Demographic data, medical history, and falls occurrence in the previous 12 months were collected at baseline by a self-report mailed questionnaire completed while the participant was blind to group assignment (before group allocation). Self-reported disability, and objectively measured musculoskeletal and cardiovascular impairment, and functional limitations were recorded by trained staff in a community venue and have been reported elsewhere.17 Analyses The primary outcome was all falls reported from intervention commencement until participants discontinued calendar return or completed the intervention period. Participants who stopped attending in the exercise programs were encouraged to continue using the calendars to report falls. Multiple falls were included and participants had variable follow-up times depending on when falls
L. Day et al. / JAMDA xxx (2015) 1e7
3
Received posted invitation letter (n=14,358) Attended information session (n=354) Did not respond (n=13,475)
Enrollment Assessed for eligibility (n=1237)
Excluded (n=734) Not meeting inclusion criteria (n=583) Eligible, excess to requirements (n=151)
Randomized (n=503)
Allocation
Allocated to control/intervention Received allocation Did not receive allocation Did not start program Received other
Control
Intervention
(n=253) (n=227) (n=25) =23 =2
(n=250) (n=221) (n=29) =28 =1
Follow-Up Control
Intervention
Discontinued intervention 24 weeks Class cancelled Deceased Health issues Schedule issues Didn’t like Other
(n=64) =0 =3 =16 =5 =10 =30
(n=108) =5 =0 =34 =5 =9 =55
Discontinued intervention 25-48 weeks Second 24 wk term not offered Class cancelled Deceased Health issues Schedule issues Didn’t like Other
(n=65) =23 =0 =1 =11 =16 =3 =11
(n=71) =37 =18 =1 =5 =3 =2 =5
=48 =181 =165
=46 =178 =154
Control (n=205)
Intervention (n=204)
=48
=46
(n=205)
(n=204)
=48 =23
=46 =37
Falls surveillance* Refused calendars (all) Complete all months first 24 wks Complete all months full 48 wks
Analyzed first 24 weeks Excluded from analysis No falls surveillance
Analysis
Analyzed full 48 weeks Excluded from analysis No falls surveillance Part 2 not offered *Some parcipants completed calendars aer disconnuing intervenon
Fig. 1. Participant flow chart: Exercise for Independent Living Trial, Melbourne, Australia.
surveillance ceased. We used negative binomial regression models to compare the number of falls in the 2 groups. These models assume a Poisson distribution, allowing for overdispersion, and included the number of falls and the variable follow-up times. However, we used Poisson regression models to compare the number of injurious falls in the 2 groups as model testing indicated that the overdispersion parameter was equal to zero and, therefore, was a better fit for this data subset than the negative binomial. Falls outcomes were analyzed at 2 time points: from commencement to the end of the first 24 weeks, and from commencement to the end of 48 weeks.
We assessed the influence of minor baseline differences in strong falls risk factors by comparing results with and without adjustment.30 Risk factors were retained in the adjusted model if there was a change of 5% or more in the intervention effect. The stratification factor (type of residence) was included in the adjusted model. Interaction terms for the participant’s assigned group and average level of attendance were tested and excluded on the basis of there being no statistically significant interactions present at either time point. Because of variable class attendance and the high proportion of intervention participants who ceased attending the exercise classes,
4
L. Day et al. / JAMDA xxx (2015) 1e7
Table 1 Baseline Characteristics of Participants With Falls Surveillance Data: Exercise for Independent Living Trial, Melbourne, Australia Characteristic
Control n ¼ 205 n
Age groups 70e74 years 75e79 years 80e84 years 85 years Gender Female Type of residence Retirement village Community-dwelling Fall history Fallen previous 12 months Fall related hospital admission previous 12 months Currently taking prescription medication Diabetes Arthritis Age (years) Strength and balance Quadriceps strength right (k) Quadriceps strength left (k) Postural sway eyes open (log mm2) Postural sway eyes closed (log mm2) Timed up and go (seconds) Timed chair stands (seconds) Step test right (steps) Step test left (steps) Berg Balance Scale (score) Beck Depression Inventory score Body mass index
Intervention n ¼ 204 %
n
%
64 64 56 21
31.2 31.2 27.3 10.2
69 62 50 23
33.8 30.4 24.5 11.3
143
69.8
142
69.6
46 158
22.4 77.1
44 160
21.6 78.4
61 6 183 25 122 Mean
29.8 2.9 89.3 12.2 59.5 SD
59 10 190 17 125 Mean
28.9 4.9 93.1 8.3 61.3 SD
77.8
5.0
77.6
5.1
19.9 20.2 5.5 6.0 10.1 9.3 12.4 12.5 7.5 7.0 27.9
8.4 8.8 0.9 0.9 7.5 5.1 3.6 3.6 1.3 5.4 4.8
19.4 19.4 5.6 6.0 10.1 9.7 12.1 12.3 7.7 7.1 27.3
8.3 8.4 0.8 0.9 7.5 5.6 3.4 3.5 0.9 4.8 3.9
we examined fall rates at different levels of adherence. Average weekly attendance levels were calculated for each group for the first 24- and full 48-week periods and stratified into 3 categories (
