Abstract
BACKGROUND:
Falling is a common but devastating and costly problem of aging. There is no consensus in the literature on whether the spatial and temporal gait parameters could identify elderly people at risk of recurrent falls.
OBJECTIVE:
To determine whether spatiotemporal gait parameters could predict recurrent falls in elderly women.
METHOD:
One hundred and forty-eight elderly women (65-85 years) participated in this study. Seven spatiotemporal gait parameters were collected with the GAITRite(r) system. Falls were recorded prospectively during 12 months through biweekly phone contacts. Elderly women who reported two or more falls throughout the follow-up period were considered as recurrent fallers. Principal component analysis (PCA) and discriminant analysis followed by biplot graph interpretation were applied to the gait parameters.
RESULTS:
After 12 months, 23 elderly women fell twice or more and comprised the recurrent fallers group and 110 with one or no falls comprised the non-recurrent fallers group. PCA resulted in three components that explained 88.3% of data variance. Discriminant analysis showed that none of the components could significantly discriminate the groups. However, visual inspection of the biplot showed a trend towards group separation in relation to gait velocity and stance time. PC1 represented gait rhythm and showed that recurrent fallers tend to walk with lower velocity and cadence and increased stance time in relation to non-recurrent fallers.
CONCLUSIONS:
The analyzed spatiotemporal gait parameters failed to predict recurrent falls in this sample. The PCA-biplot technique highlighted important trends or red flags that should be considered when evaluating recurrent falls in elderly females.
falls; elderly; gait; principal component analysis; biplot; physical therapy
Introduction
Falls among older adults are a major public health concern due to their high incidence,
substantial morbimortality rate, and high associated healthcare costs11. Ambrose AF, Paul G, Hausdorff JM. Risk factors for falls among older
adults: a review of the literature. Maturitas. 2013;75(1):51-61.
http://dx.doi.org/10.1016/j.maturitas.2013.02.009. PMid:23523272
http://dx.doi.org/10.1016/j.maturitas.20...
. It is estimated that 30 to 60% of
community-dwelling elderly people fall each year, with approximately half of them
experiencing multiple falls22. Rubenstein LZ, Josephson KR. The epidemiology of falls and syncope.
Clin Geriatr Med. 2002;18(2):141-58. http://dx.doi.org/10.1016/S0749-0690(02)00002-2.
PMid:12180240
http://dx.doi.org/10.1016/S0749-0690(02)...
, and that 10 to 20%
of these falls result in injury, hospitalization, and/or death33. Rubenstein LZ. Falls in older people: epidemiology, risk factors and
strategies for prevention. Age Ageing. 2006;35(Suppl 2):ii37-41.
http://dx.doi.org/10.1093/ageing/afl084. PMid:16926202
http://dx.doi.org/10.1093/ageing/afl084...
. Falls also generate serious psychological and social
consequences. Individuals may experience fear of falling, activity restriction, and loss
of confidence, which may consequently facilitate further functional decline, depression,
and social isolation44. Peel NM. Epidemiology of falls in older age. Can J Aging.
2011;30(1):7-19. http://dx.doi.org/10.1017/S071498081000070X.
PMid:21401978
http://dx.doi.org/10.1017/S0714980810000...
. Considering these adverse
outcomes, it is imperative to proactively identify individuals at risk for falling.
During the last decade, gait velocity has been repeatedly reported as an appealing,
quick, inexpensive, and highly reliable tool in research and clinical practice to assess
elderly people at a high risk of negative outcomes55. Abellan van Kan G, Rolland Y, Andrieu S, Bauer J, Beauchet O,
Bonnefoy M, et al. Gait speed at usual pace as a predictor of adverse outcomes in
community-dwelling older people an International Academy on Nutrition and Aging
(IANA) Task Force. J Nutr Health Aging. 2009;13(10):881-9.
http://dx.doi.org/10.1007/s12603-009-0246-z. PMid:19924348
http://dx.doi.org/10.1007/s12603-009-024...
, such as falls and recurrent falls. However, its capacity to predict
recurrent falls has not been consistently observed. Some previous prospective studies
have shown that slow gait velocity is associated with recurrent falls in the elderly
population66. Chu LW, Chi I, Chiu AY. Incidence and predictors of falls in the
chinese elderly. Ann Acad Med Singapore. 2005;34(1):60-72.
PMid:15726221.
7. Nevitt MC, Cummings SR, Hudes ES. Risk factors for injurious falls: a
prospective study. J Gerontol. 1991;46(5):M164-70.
http://dx.doi.org/10.1093/geronj/46.5.M164. PMid:1890282
http://dx.doi.org/10.1093/geronj/46.5.M1...
-
88. Viccaro LJ, Perera S, Studenski SA. Is timed up and go better than
gait speed in predicting health, function, and falls in older adults? J Am Geriatr
Soc. 2011;59(5):887-92. http://dx.doi.org/10.1111/j.1532-5415.2011.03336.x.
PMid:21410448
http://dx.doi.org/10.1111/j.1532-5415.20...
. For example, in a community-based prospective
study with a 2-year follow-up conducted in 1,016 participants aged 70 years and older,
Luukinen et al.99. Luukinen H, Koski K, Laippala P, Kivelä SL. Predictors for recurrent
falls among the home-dwelling elderly. Scand J Prim Health Care. 1995;13(4):294-9.
http://dx.doi.org/10.3109/02813439508996778. PMid:8693215
http://dx.doi.org/10.3109/02813439508996...
found that slow walking velocity
(<0.77m/s) was an independent risk factor for recurrent falls (age- and sex-adjusted
odds ratio=1.79, 95%CI=1.06-3.00). Conversely, other prospective studies failed to
observe a significant association between gait velocity and future recurrent falls in
older adults1010. Hill K, Schwarz J, Flicker L, Carroll S. Falls among healthy,
community-dwelling, older women: a prospective study of frequency, circumstances,
consequences and prediction accuracy. Aust N Z J Public Health. 1999;23(1):41-8.
http://dx.doi.org/10.1111/j.1467-842X.1999.tb01203.x. PMid:10083688
http://dx.doi.org/10.1111/j.1467-842X.19...
11. Lord SR, Lloyd DG, Li SK. Sensori-motor function, gait patterns and
falls in community-dwelling women. Age Ageing. 1996;25(4):292-9.
http://dx.doi.org/10.1093/ageing/25.4.292. PMid:8831874
http://dx.doi.org/10.1093/ageing/25.4.29...
-
1212. Paterson K, Hill K, Lythgo N. Stride dynamics, gait variability and
prospective falls risk in active community dwelling older women. Gait Posture.
2011;33(2):251-5. http://dx.doi.org/10.1016/j.gaitpost.2010.11.014.
PMid:21167715
http://dx.doi.org/10.1016/j.gaitpost.201...
.
Gait is a complex motor activity with many measurable facets besides velocity that could
help to identify individuals with recurrent falls. In a study involving 96
community-dwelling elderly women (72.8±6.2 years), Lord et al.1111. Lord SR, Lloyd DG, Li SK. Sensori-motor function, gait patterns and
falls in community-dwelling women. Age Ageing. 1996;25(4):292-9.
http://dx.doi.org/10.1093/ageing/25.4.292. PMid:8831874
http://dx.doi.org/10.1093/ageing/25.4.29...
demonstrated that elderly women who fell on two or more occasions
in a one-year prospective period had significantly reduced cadence and increased stance
time than those who did not fall or fell on one occasion only. On the other hand, Hill
et at.1010. Hill K, Schwarz J, Flicker L, Carroll S. Falls among healthy,
community-dwelling, older women: a prospective study of frequency, circumstances,
consequences and prediction accuracy. Aust N Z J Public Health. 1999;23(1):41-8.
http://dx.doi.org/10.1111/j.1467-842X.1999.tb01203.x. PMid:10083688
http://dx.doi.org/10.1111/j.1467-842X.19...
identified that double support phase was
associated with prediction of recurrent falls in a group of 96 healthy, active
community-dwelling women aged 70 years and older. Therefore, it remains unclear whether
and to what extent gait velocity and other gait parameters predict recurrent falls in
the elderly population.
The present study investigated whether gait velocity and other spatiotemporal gait parameters could predict recurrent falls in a group of community-dwelling women aged 65 years or more. The understanding of the relationship between the gait pattern changes and falls can help health professionals and researchers to develop appropriate preventive approaches and therapeutic interventions to reduce the occurrence of falls in the elderly.
Method
Participants
One hundred forty-eight elderly women (65-85 years) were recruited on a volunteer
basis from the general community of Belo Horizonte, MG, Brazil. The inclusion
criteria were women aged 65 years or older, living independently in the community and
able to walk without walking-aid devices. The exclusion criteria were cognitive
impairment detectable by the Mini-Mental State Examination (MMSE) using the Brazilian
cutoff points based on the degree of education1313. Bertolucci PH, Brucki SM, Campacci SR, Juliano Y. [The mini-mental
state examination in a general population: impact of educational status]. Arq
Neuropsiquiatr. 1994;52(1):1-7. http://dx.doi.org/10.1590/S0004-282X1994000100001.
PMid:8002795
http://dx.doi.org/10.1590/S0004-282X1994...
, vestibular symptoms, motor sequel due to rheumatic, orthopedic and/or
neurological diseases, strong pain in the spine or lower limbs, accentuated postural
deviation, severe foot deformity, visual impairment not corrected by lenses, auditory
impairment not corrected by hearing aids, and history of fracture and/or surgery in
lower limbs in the past two years. The Ethics Committee from Universidade Federal de
Minas Gerais (UFMG), Belo Horizonte, MG, Brazil approved this study (protocol
442/08), and written consent was obtained from all participants.
Measures and procedures
At baseline, sociodemographic and clinical data were collected and psychological and
balance measures known to influence falls risk, as described elsewhere, were
completed1414. Alexandre TS, Meira DM, Rico NC, Mizuta SK. Accuracy of timed up and
go test for screening risk of falls among community-dwelling elderly. Rev Bras
Fisioter. 2012;16(5):381-8. http://dx.doi.org/10.1590/S1413-35552012005000041.
PMid:22858735
http://dx.doi.org/10.1590/S1413-35552012...
15. Friedman SM, Munoz B, West SK, Rubin GS, Fried LP. Falls and fear of
falling: which comes first? A longitudinal prediction model suggests strategies for
primary and secondary prevention. J Am Geriatr Soc. 2002;50(8):1329-35.
http://dx.doi.org/10.1046/j.1532-5415.2002.50352.x. PMid:12164987
http://dx.doi.org/10.1046/j.1532-5415.20...
-
1616. Lopes KT, Costa DF, Santos LF, Castro DP, Bastone AC. Prevalence of
fear of falling among a population of older adults and its correlation with mobility,
dynamic balance, risk and history of falls. Rev Bras Fisioter. 2009;13(3):223-9.
http://dx.doi.org/10.1590/S1413-35552009005000026.
http://dx.doi.org/10.1590/S1413-35552009...
. Anthropometric data and information about
physical exercise were also collected. Participants who reported regular aerobic or
strength training two or more times a week were considered as active.
Psychological measures included fear of falling evaluated through the question "Are
you afraid of falling?", with a yes or no answer and self-efficacy or confidence of
avoiding a fall during activities of daily living assessed using the Brazilian
version of the Falls Efficacy Scale-International (FES-I)1717. Camargos FF, Dias RC, Dias JM, Freire MT. Cross-cultural adaptation
and evaluation of the psychometric properties of the falls efficacy
scale-international among elderly brazilians (FES-I-BRAZIL). Rev Bras Fisioter.
2010;14(3):237-43. http://dx.doi.org/10.1590/S1413-35552010000300010.
PMid:20730369
http://dx.doi.org/10.1590/S1413-35552010...
. The FES-I scores range from 16 to 64, with higher scores
representing lower self-efficacy for falls or greater concern about falling.
Dynamic balance was assessed with the Timed Up and Go (TUG)1818. Herman T, Giladi N, Hausdorff JM. Properties of the 'timed up and
go' test: more than meets the eye. Gerontology. 2011;57(3):203-10.
http://dx.doi.org/10.1159/000314963. PMid:20484884
http://dx.doi.org/10.1159/000314963...
. This test quantifies the time taken for an individual to rise
from a chair, walk 3 m, turn around, walk back to the chair and sit again1919. Podsiadlo D, Richardson S. The timed "up & go": a test of basic
functional mobility for frail elderly persons. J Am Geriatr Soc. 1991;39(2):142-8.
PMid:1991946.. The participants walked as fast and safely as
possible. A trial run was first performed for the subjects to become familiarized
with the test and then the TUG was recorded twice. The final score was calculated as
the mean of the two trials.
Spatiotemporal gait parameters
Gait parameters (velocity, cadence, step length, base of support, swing time, stance time, and double support time) were collected with a 5.74 m computerized carpet (GAITRite, CIR Systems, USA). Participants were asked to walk on the mat at their usual pace for six trials. The beginning and end of the course were delimited by cones placed 2 m from the edge of the mat for acceleration and deceleration. The following instruction was given: "Please walk to the cone at your usual speed, go!". Data were processed using the GAITRite(r) software version 3.9. Data from all trials were combined and considered as a single test.
Falls
A fall was defined as unintentionally coming to the ground or some lower level2020. Swanenburg J, de Bruin ED, Uebelhart D, Mulder T. Falls prediction
in elderly people: a 1-year prospective study. Gait Posture. 2010;31(3):317-21.
http://dx.doi.org/10.1016/j.gaitpost.2009.11.013. PMid:20047833
http://dx.doi.org/10.1016/j.gaitpost.200...
. The loss of consciousness or sudden onset of
paralysis resulting in a fall (stroke or epileptic seizure) and falling as a
consequence of sustaining a violent blow and high-trauma falls were not considered as
falls2020. Swanenburg J, de Bruin ED, Uebelhart D, Mulder T. Falls prediction
in elderly people: a 1-year prospective study. Gait Posture. 2010;31(3):317-21.
http://dx.doi.org/10.1016/j.gaitpost.2009.11.013. PMid:20047833
http://dx.doi.org/10.1016/j.gaitpost.200...
. Falls were assessed both
retrospectively and prospectively. Retrospective falls were assessed during the
initial interview. Participants were asked how many times they had fallen in the
previous 12 months. During the following year, participants were contacted by phone
every 15 days and asked about the occurrence of falls, and in case of falls, the
circumstances and consequences were obtained. Telephone calls were conducted by the
research assistants who were unaware of the previous fall conditions of the
participants. To avoid recall bias, participants with missed phone calls for a
3-month period were excluded from the study. Participants who reported two or more
falls during the follow-up were categorized as "recurrent fallers" whereas
participants who experienced no falls or only one fall were considered "non-recurrent
fallers".
Statistical analysis
Independent t test and Mann-Whitney test with Bonferroni's correction and chi-square test were used to compare baseline characteristics between the recurrent and non-recurrent fallers groups. All the data were analyzed with a significance level of 0.05.
Gait parameters were first standardized and mean-centered to maximize the variance.
The principal components (PCs) were extracted from the matrix through a method called
singular value decomposition that realigns the data into the direction of the maximum
variation2121. Jolliffe IT. Principal Component Analysis. 2nd ed. New York:
Springer; 2004.. PCs are uncorrelated and
displayed according to the amount of variance explained - known as eigenvalue. The
first PC (PC1) explains more of the total variance, followed by PC2, PC3, and so
forth2222. Astephen JL, Deluzio KJ. Changes in frontal plane dynamics and the
loading response phase of the gait cycle are characteristic of severe knee
osteoarthritis application of a multidimensional analysis technique. Clin Biomech
(Bristol, Avon). 2005;20(2):209-17.
http://dx.doi.org/10.1016/j.clinbiomech.2004.09.007. PMid:15621327
http://dx.doi.org/10.1016/j.clinbiomech....
. A lack of correlation means that
the PCs are measuring different features. Interpretation of the components is based
on the contribution of the variables to each PC2323. Kirkwood RN, Brandon SC, Moreira BS, Deluzio KJ. Searching for
stability as we age: the PCA-Biplot approach. Int J Stats Med Res.
2013;2(4):255-62.. In the present study, only the gait parameters whose contribution was
equal to or greater than -/+ 0.40 were considered in the composition of each PC2121. Jolliffe IT. Principal Component Analysis. 2nd ed. New York:
Springer; 2004..
The structure of the PCs combined with the individual standardized variables results
in the subjects' scores, which represent the distance each individual is from the
mean of one specific component2222. Astephen JL, Deluzio KJ. Changes in frontal plane dynamics and the
loading response phase of the gait cycle are characteristic of severe knee
osteoarthritis application of a multidimensional analysis technique. Clin Biomech
(Bristol, Avon). 2005;20(2):209-17.
http://dx.doi.org/10.1016/j.clinbiomech.2004.09.007. PMid:15621327
http://dx.doi.org/10.1016/j.clinbiomech....
. The
resultant PC scores were submitted to a linear discriminant analysis to determine
which PCs could discriminate the groups.
In addition, to better understand the relation among the gait parameters and the
behavior of the groups in relation to each other and to the gait parameters, a
PCA-biplot was built. The PCA-biplot has its axes represented by the first two
components, with maximum variance - PC1 and PC2. Interpretation of the biplot
involves observing the length, proximity, and direction of the variables' vectors.
The length of each vector approximates the amount of variance in each original
variable that is captured by the 2-PC model; where longer vectors indicate higher
variance2424. Kohler U, Luniak M. Data inspection using biplots. Stata J.
2005;5(2):208-23.. The angle between two
variables' vectors represents their pairwise correlation - the closer the vectors are
to each other, the higher their correlation2525. De Wit L, Molas M, Dejaeger E, De Weerdt W, Feys H, Jenni W, et al.
The use of a biplot in studying outcomes after stroke. Neurorehabil Neural Repair.
2009;23(8):825-30. http://dx.doi.org/10.1177/1545968309337137.
PMid:19498014
http://dx.doi.org/10.1177/15459683093371...
.
The direction of the variables' vectors with respect to the axes indicates the PC to
which each variable is most strongly related.
Another important characteristic that can be extracted from the PCA-biplot is the spatial proximity or distance of the groups in relation to each other and to a set of variables, which reflects their similarities. When the perpendicular projection of the groups falls in the direction of the variables' vectors (solid line), the average value for the groups for these specific variables is higher. If the projection falls in the opposite direction of the vectors, i.e. on the extension of the vectors (dotted line), the average value for the groups for these specific variables would be lower. In addition, the projection on the variables' vectors that shows higher distance between the groups could be interpreted as the most important variable in group separation.
Results
Of the 148 participants who entered the study, 133 (89.9%) completed the follow-up period. The dropout rate was 10.1%: 7 elderly women refused to continue participation in the study, 3 had health issues, 1 died, and 4 participants were excluded due to missed phone contacts over a 3-month period. There were no significant differences in the descriptive characteristics and gait parameters between those who lost the follow-up and those included in the analyses.
The one year prospective monitoring period showed a total of 23 (17.3%) recurrent fallers with a range of 2 to 9 falls and 110 (82.7%) non-recurrent fallers (40 one-time fallers and 70 did not fall). Overall, 108 falls were recorded, of which 68 (63%) resulted in injuries. The most severe injuries reported included one knee joint dislocation and three fractures (arm, nose, and wrist). Falls occurred more often outside their home (55.6%), while walking on the street or sidewalk (25.9%). Tripping was the most common perceived cause of the falls (45.4%).
Baseline participants' characteristics are summarized in Table 1. A significantly higher proportion of the participants in the recurrent fallers group (39%) reported two or more falls in the year prior to the beginning of the study compared to the non-recurrent fallers group (14%; p=0.007). No other significant differences were observed between the groups with regard to descriptive characteristics. Table 2 displays the spatiotemporal gait parameters for total sample and both groups.
Mean±standard deviation of the spatiotemporal gait parameters of all participants and for recurrent fallers and non-recurrent fallers groups.
PCA resulted in three components that explained 88.3% of the data variance. The loading vectors presented on Table 3 show the contribution of each gait parameter to the PCs, with the accumulated percentage of the total variance. PC1 had higher contribution from velocity, cadence, and stance time. PC2 had similar contribution from the variables step length and swing time and PC3 was heavily loaded with base of support.
Linear discriminant analysis with a stepwise procedure was conducted with the three components. The covariance matrices were similar between groups (p=0.304); however, the Wilks' lambda test was not statistically significant (p>0.05), indicating that none of the three components could discriminate the recurrent fallers group from the non-recurrent fallers group.
Following, the PCA-biplot shown on Figure 1 was built with the x-axis represented by PC1 and the y-axis by PC2, the first two components that carry most of the explained variance. The average score of each group is represented by symbols and the gait parameters by vectors. The configuration of the PCA-biplot shows that most of the variables are well represented in the PC1 and PC2 dimensions with base of support showing the shortest vector. The highest relative variance is attributed to step length and swing time with the longest vectors. The variables velocity and step length showed the highest correlation due to the closest proximity.
PCA-biplot with the average scores from the recurrent fallers and non-recurrent fallers groups.
The projection of the average score of the recurrent fallers group onto the variables' vectors shows that recurrent fallers walked with lower velocity, cadence, and step length and increased swing and stance time. The projection of the non-recurrent fallers group on the vectors shows the opposite pattern: higher velocity, cadence, and step length and lower swing and stance time. The highest distances between the groups are along the vectors of the variables velocity and stance time; therefore, these two variables or PC1 are important for group separation. PC1 had higher contribution from the variables velocity and cadence, with the vectors going in a negative direction, and from stance time with the vector going in a positive direction. Therefore, PC1 is a measure of rhythm since a decreased velocity and cadence and increased stance time would decrease rhythm and the opposite would increase the gait rhythm.
For a thorough interpretation of the behavior of the groups in relation to the dimension rhythm or PC1, Table 4 was built with the coefficients from PC1 represented only by signs, positive (+) or negative (-), according to the direction of the variables' vectors. In addition, in order to simplify interpretation, when the projection of the average group score fell in the direction of the variables' vector (solid line), one plus (+) sign was assigned, indicating high value and when the projection fell on the extension of the vector (dotted line), a negative (-) sign was assigned, indicating low value. The objective was to interpret the results of the biplot within the structure of PC1. The results showed that recurrent fallers tend to decrease their rhythm when walking and non-recurrent fallers do the opposite, increase their rhythm. Although the statistical test failed to show group discrimination, the interpretation from the PCA-biplot shows a trend from the recurrent fallers to decrease the gait rhythm by decreasing velocity and cadence and increasing the time spent in stance.
Discussion
The aging world population is characterized by a predominance of females2626. Davidson PM, Digiacomo M, McGrath SJ. The feminization of aging: how
will this impact on health outcomes and services? Health Care Women Int.
2011;32(12):1031-45. http://dx.doi.org/10.1080/07399332.2011.610539.
PMid:22087593
http://dx.doi.org/10.1080/07399332.2011....
. Additionally, when compared to men, women have a
higher risk of falling11. Ambrose AF, Paul G, Hausdorff JM. Risk factors for falls among older
adults: a review of the literature. Maturitas. 2013;75(1):51-61.
http://dx.doi.org/10.1016/j.maturitas.2013.02.009. PMid:23523272
http://dx.doi.org/10.1016/j.maturitas.20...
. Factors such as
genetics, lifestyle, longevity, and frailty have been pointed out as potential reasons
for the increased risk of falls among women2727. Coimbra AM, Ricci NA, Coimbra IB, Costallat LT. Falls in the elderly
of the family health program. Arch Gerontol Geriatr. 2010;51(3):317-22.
http://dx.doi.org/10.1016/j.archger.2010.01.010. PMid:20153535
http://dx.doi.org/10.1016/j.archger.2010...
.
Therefore, it is essential to deliver appropriate support to this vulnerable group. The
aim of this study was to investigate, by means of PCA and discriminant analysis, whether
gait velocity and other spatiotemporal gait parameters could predict recurrent falls in
a sample of community-dwelling elderly women. Since gait parameters are highly
correlated2323. Kirkwood RN, Brandon SC, Moreira BS, Deluzio KJ. Searching for
stability as we age: the PCA-Biplot approach. Int J Stats Med Res.
2013;2(4):255-62., the use of multivariate
statistic techniques is appropriate for examining the independent effect of these
parameters on the likelihood of recurrent falls. Furthermore, the PCA-biplot was
introduced to clarify interpretation of the principal components2828. Gabriel KR. The biplot graphic display of matrices with application
to principal component analysis. Biometrika. 1971;58(3):453-67.
http://dx.doi.org/10.1093/biomet/58.3.453.
http://dx.doi.org/10.1093/biomet/58.3.45...
.
Our results showed that neither gait velocity nor the other gait parameters
significantly predicted recurrent falls. These results are consistent with another
prospective study that also found that none of the gait variables could predict
recurrent falls1212. Paterson K, Hill K, Lythgo N. Stride dynamics, gait variability and
prospective falls risk in active community dwelling older women. Gait Posture.
2011;33(2):251-5. http://dx.doi.org/10.1016/j.gaitpost.2010.11.014.
PMid:21167715
http://dx.doi.org/10.1016/j.gaitpost.201...
. In a 1-year follow-up
conducted in 97 healthy active women (68.73±7.07 years), Paterson et al.1212. Paterson K, Hill K, Lythgo N. Stride dynamics, gait variability and
prospective falls risk in active community dwelling older women. Gait Posture.
2011;33(2):251-5. http://dx.doi.org/10.1016/j.gaitpost.2010.11.014.
PMid:21167715
http://dx.doi.org/10.1016/j.gaitpost.201...
observed that none of the spatiotemporal gait
parameters (velocity, stride length, foot angle, base of support, stride time, stance
time, and swing time) differed significantly between multiple fallers (two or more
falls) and non-multiple fallers.
Conversely, one recent prospective population-based study that used the same gait
analysis system as the present study found an association between spatiotemporal gait
parameters and the risk of recurrent falls2929. Callisaya ML, Blizzard L, Schmidt MD, Martin KL, McGinley JL,
Sanders LM, et al. Gait, gait variability and the risk of multiple incident falls in
older people: a population-based study. Age Ageing. 2011;40(4):481-7.
http://dx.doi.org/10.1093/ageing/afr055. PMid:21628390
http://dx.doi.org/10.1093/ageing/afr055...
.
Callisaya et al.2929. Callisaya ML, Blizzard L, Schmidt MD, Martin KL, McGinley JL,
Sanders LM, et al. Gait, gait variability and the risk of multiple incident falls in
older people: a population-based study. Age Ageing. 2011;40(4):481-7.
http://dx.doi.org/10.1093/ageing/afr055. PMid:21628390
http://dx.doi.org/10.1093/ageing/afr055...
observed in 412 elderly
individuals (both sexes, 60-86 years) that gait velocity and cadence were associated in
a nonlinear way with the risk of multiple falls. The spatiotemporal gait parameters were
divided into quarters, and the results for gait velocity showed that the participants in
the second quarter (velocity between 1.02 and 1.16 m/s) showed a lower risk of suffering
recurrent falls. These results indicate that a gait velocity greater than 1.02 m/s
protects against recurrent falls, but this protective effect is reduced when gait
velocity exceeds 1.16 m/s. According to the authors, this reduction in protection occurs
because some elderly individuals walk too fast for their physical capabilities or
participate in high-risk physical activities, which places them at a higher risk of
falling. Furthermore, they observed that greater variability in step length and double
support phase was independently and linearly associated with increased risk of multiple
falls. Thus, this result suggests that gait variability measures may be more sensitive
in predicting recurrent falls than more conventional gait parameters, such as
velocity.
The population-based study described above adopted broader selection criteria, including
participants with health conditions that affect mobility and gait, such as dementia,
stroke, and Parkinson's disease2929. Callisaya ML, Blizzard L, Schmidt MD, Martin KL, McGinley JL,
Sanders LM, et al. Gait, gait variability and the risk of multiple incident falls in
older people: a population-based study. Age Ageing. 2011;40(4):481-7.
http://dx.doi.org/10.1093/ageing/afr055. PMid:21628390
http://dx.doi.org/10.1093/ageing/afr055...
. Thus, the
inclusion of participants with walking disabilities and the differences between
participants in characteristics like sex may explain the different results between the
present study and the study by Callisaya et al.2929. Callisaya ML, Blizzard L, Schmidt MD, Martin KL, McGinley JL,
Sanders LM, et al. Gait, gait variability and the risk of multiple incident falls in
older people: a population-based study. Age Ageing. 2011;40(4):481-7.
http://dx.doi.org/10.1093/ageing/afr055. PMid:21628390
http://dx.doi.org/10.1093/ageing/afr055...
.
Our study has several strengths. The prospective record of falls and the biweekly
contact with participants minimized the potential occurrence of recall bias. This study
had low attrition rate for the follow-up (10.1%), and the participants who completed and
did not complete the follow-up were similar. In addition, we adopted rigorous
eligibility criteria, resulting in a homogenous sample with well-defined
characteristics. The participants in our sample were relatively young (average
age=71.6), did not exhibit cognitive impairments, had few comorbidities, used very
little medication, and had excellent dynamic balance, as demonstrated by their
performance on the TUG test3030. Bohannon RW. Reference values for the timed up and go test: a
descriptive meta-analysis. J Geriatr Phys Ther. 2006;29(2):64-8.
http://dx.doi.org/10.1519/00139143-200608000-00004. PMid:16914068
http://dx.doi.org/10.1519/00139143-20060...
. Furthermore,
compared to gait normative data of healthy and robust elderly women of the same age
group3131. Hollman JH, McDade EM, Petersen RC. Normative spatiotemporal gait
parameters in older adults. Gait Posture. 2011;34(1):111-8.
http://dx.doi.org/10.1016/j.gaitpost.2011.03.024. PMid:21531139
http://dx.doi.org/10.1016/j.gaitpost.201...
, our participants performed better in
most of the spatiotemporal gait parameters. Considering the sample profile and the
circumstances by which the majority of falls occurred, it can be inferred that other
factors minimally related to gait contributed to the number of falls amongst our
participants. These factors include environmental risks and degree of exposure to
situations that present an inherently high fall risk. Therefore, our results are
meaningful because they reveal that healthy elderly women without mobility dysfunction
may also fall, but spatial and temporal gait data are not predictive of those falls.
In this study, the groups of elderly women were similar in all evaluated descriptive
characteristics, except for their history of falls. A significantly higher proportion of
the participants in the recurrent fallers group reported two or more falls during the
year prior to the study compared to non-recurrent fallers. Although this information is
retrospective and subject to recall bias, it was previously demonstrated that a history
of two or more falls in the previous year is an important risk factor for recurrent
falls in the community-dwelling elderly3232. Stalenhoef PA, Diederiks JP, Knottnerus JA, Kester AD, Crebolder HF.
A risk model for the prediction of recurrent falls in community-dwelling elderly: a
prospective cohort study. J Clin Epidemiol. 2002;55(11):1088-94.
http://dx.doi.org/10.1016/S0895-4356(02)00502-4. PMid:12507672
http://dx.doi.org/10.1016/S0895-4356(02)...
.
Therefore, our results support existing knowledge and indicate that a history of
recurrent falls should be considered in the assessment of elderly individuals, since
those who fall in a recurrent manner have a higher chance of falling multiple times in
the following year.
In recent years, statistical approaches, such as PCA, have been used to analyze gait
data2323. Kirkwood RN, Brandon SC, Moreira BS, Deluzio KJ. Searching for
stability as we age: the PCA-Biplot approach. Int J Stats Med Res.
2013;2(4):255-62.
,
3333. Kirkwood RN, Resende RA, Magalhães CM, Gomes HA, Mingoti SA, Sampaio
RF. Application of principal component analysis on gait kinematics in elderly women
with knee osteoarthritis. Rev Bras Fisioter. 2011;15(1):52-8.
http://dx.doi.org/10.1590/S1413-35552011000100007. PMid:21519716
http://dx.doi.org/10.1590/S1413-35552011...
. One of the major challenges of this analysis
is its interpretation. In this study, the biplot technique was used to explore the
contribution of the gait variables to the components2323. Kirkwood RN, Brandon SC, Moreira BS, Deluzio KJ. Searching for
stability as we age: the PCA-Biplot approach. Int J Stats Med Res.
2013;2(4):255-62.. The biplot revealed that the groups are very far apart in relation to
gait velocity and stance time. Previous studies demonstrated the importance of these
gait parameters in differentiating elderly recurrent fallers from non-recurrent
fallers66. Chu LW, Chi I, Chiu AY. Incidence and predictors of falls in the
chinese elderly. Ann Acad Med Singapore. 2005;34(1):60-72.
PMid:15726221.
,
1111. Lord SR, Lloyd DG, Li SK. Sensori-motor function, gait patterns and
falls in community-dwelling women. Age Ageing. 1996;25(4):292-9.
http://dx.doi.org/10.1093/ageing/25.4.292. PMid:8831874
http://dx.doi.org/10.1093/ageing/25.4.29...
. Further interpretation of PC1 revealed that
the variables' contribution described gait rhythm. Recurrent fallers tend to slow their
rhythm when they walk, while non-recurrent fallers exhibit an opposite walking pattern
characterized by an increased gait rhythm. Although group discrimination is not
statistically significant in the observations, these trends cannot be rejected.
Clinically, these trends could be considered as red flags - an indication that elderly
individuals in these conditions may be more susceptible to recurrent falls. Therefore,
the biplot was able to capture a tendency towards group separation and identify an
underlying pattern (rhythm) that could not be seen when applying traditional statistical
tests.
There are certain limitations to this study. Since sample selection was based on convenience, the generalizability of the findings is limited. Second, gait variability was not measured in our study; thus, not all possible aspects of gait that potentially contribute to recurrent falls in the elderly were studied. Finally, gait was tested at the usual pace, which might not have been sensitive enough to reflect the recurrent fall risk of participants. Future studies should investigate the capacity for gait parameters to predict recurrent falls in healthy elderly individuals without mobility impairment in "real life" situations, such as walking over obstacles or performing cognitive and motor tasks (e.g. speaking, making calculations or carrying objects). It is possible that more challenging tasks may place greater demand on physiological and cognitive systems and therefore be more informative about recurrent falls risk.
Conclusions
The analyzed spatiotemporal gait parameters failed to predict recurrent falls in this group of healthy, community-dwelling 65-85 year-old elderly women without mobility impairment. However, the PCA-biplot technique revealed tendencies in group separation and differences in walking patterns between groups. These findings could be used as red flags suggesting that further investigation into the gait of elderly patients should be considered.
References
-
1Ambrose AF, Paul G, Hausdorff JM. Risk factors for falls among older adults: a review of the literature. Maturitas. 2013;75(1):51-61. http://dx.doi.org/10.1016/j.maturitas.2013.02.009. PMid:23523272
» http://dx.doi.org/10.1016/j.maturitas.2013.02.009 -
2Rubenstein LZ, Josephson KR. The epidemiology of falls and syncope. Clin Geriatr Med. 2002;18(2):141-58. http://dx.doi.org/10.1016/S0749-0690(02)00002-2. PMid:12180240
» http://dx.doi.org/10.1016/S0749-0690(02)00002-2 -
3Rubenstein LZ. Falls in older people: epidemiology, risk factors and strategies for prevention. Age Ageing. 2006;35(Suppl 2):ii37-41. http://dx.doi.org/10.1093/ageing/afl084. PMid:16926202
» http://dx.doi.org/10.1093/ageing/afl084 -
4Peel NM. Epidemiology of falls in older age. Can J Aging. 2011;30(1):7-19. http://dx.doi.org/10.1017/S071498081000070X. PMid:21401978
» http://dx.doi.org/10.1017/S071498081000070X -
5Abellan van Kan G, Rolland Y, Andrieu S, Bauer J, Beauchet O, Bonnefoy M, et al. Gait speed at usual pace as a predictor of adverse outcomes in community-dwelling older people an International Academy on Nutrition and Aging (IANA) Task Force. J Nutr Health Aging. 2009;13(10):881-9. http://dx.doi.org/10.1007/s12603-009-0246-z. PMid:19924348
» http://dx.doi.org/10.1007/s12603-009-0246-z -
6Chu LW, Chi I, Chiu AY. Incidence and predictors of falls in the chinese elderly. Ann Acad Med Singapore. 2005;34(1):60-72. PMid:15726221.
-
7Nevitt MC, Cummings SR, Hudes ES. Risk factors for injurious falls: a prospective study. J Gerontol. 1991;46(5):M164-70. http://dx.doi.org/10.1093/geronj/46.5.M164. PMid:1890282
» http://dx.doi.org/10.1093/geronj/46.5.M164 -
8Viccaro LJ, Perera S, Studenski SA. Is timed up and go better than gait speed in predicting health, function, and falls in older adults? J Am Geriatr Soc. 2011;59(5):887-92. http://dx.doi.org/10.1111/j.1532-5415.2011.03336.x. PMid:21410448
» http://dx.doi.org/10.1111/j.1532-5415.2011.03336.x -
9Luukinen H, Koski K, Laippala P, Kivelä SL. Predictors for recurrent falls among the home-dwelling elderly. Scand J Prim Health Care. 1995;13(4):294-9. http://dx.doi.org/10.3109/02813439508996778. PMid:8693215
» http://dx.doi.org/10.3109/02813439508996778 -
10Hill K, Schwarz J, Flicker L, Carroll S. Falls among healthy, community-dwelling, older women: a prospective study of frequency, circumstances, consequences and prediction accuracy. Aust N Z J Public Health. 1999;23(1):41-8. http://dx.doi.org/10.1111/j.1467-842X.1999.tb01203.x. PMid:10083688
» http://dx.doi.org/10.1111/j.1467-842X.1999.tb01203.x -
11Lord SR, Lloyd DG, Li SK. Sensori-motor function, gait patterns and falls in community-dwelling women. Age Ageing. 1996;25(4):292-9. http://dx.doi.org/10.1093/ageing/25.4.292. PMid:8831874
» http://dx.doi.org/10.1093/ageing/25.4.292 -
12Paterson K, Hill K, Lythgo N. Stride dynamics, gait variability and prospective falls risk in active community dwelling older women. Gait Posture. 2011;33(2):251-5. http://dx.doi.org/10.1016/j.gaitpost.2010.11.014. PMid:21167715
» http://dx.doi.org/10.1016/j.gaitpost.2010.11.014 -
13Bertolucci PH, Brucki SM, Campacci SR, Juliano Y. [The mini-mental state examination in a general population: impact of educational status]. Arq Neuropsiquiatr. 1994;52(1):1-7. http://dx.doi.org/10.1590/S0004-282X1994000100001. PMid:8002795
» http://dx.doi.org/10.1590/S0004-282X1994000100001 -
14Alexandre TS, Meira DM, Rico NC, Mizuta SK. Accuracy of timed up and go test for screening risk of falls among community-dwelling elderly. Rev Bras Fisioter. 2012;16(5):381-8. http://dx.doi.org/10.1590/S1413-35552012005000041. PMid:22858735
» http://dx.doi.org/10.1590/S1413-35552012005000041 -
15Friedman SM, Munoz B, West SK, Rubin GS, Fried LP. Falls and fear of falling: which comes first? A longitudinal prediction model suggests strategies for primary and secondary prevention. J Am Geriatr Soc. 2002;50(8):1329-35. http://dx.doi.org/10.1046/j.1532-5415.2002.50352.x. PMid:12164987
» http://dx.doi.org/10.1046/j.1532-5415.2002.50352.x -
16Lopes KT, Costa DF, Santos LF, Castro DP, Bastone AC. Prevalence of fear of falling among a population of older adults and its correlation with mobility, dynamic balance, risk and history of falls. Rev Bras Fisioter. 2009;13(3):223-9. http://dx.doi.org/10.1590/S1413-35552009005000026.
» http://dx.doi.org/10.1590/S1413-35552009005000026 -
17Camargos FF, Dias RC, Dias JM, Freire MT. Cross-cultural adaptation and evaluation of the psychometric properties of the falls efficacy scale-international among elderly brazilians (FES-I-BRAZIL). Rev Bras Fisioter. 2010;14(3):237-43. http://dx.doi.org/10.1590/S1413-35552010000300010. PMid:20730369
» http://dx.doi.org/10.1590/S1413-35552010000300010 -
18Herman T, Giladi N, Hausdorff JM. Properties of the 'timed up and go' test: more than meets the eye. Gerontology. 2011;57(3):203-10. http://dx.doi.org/10.1159/000314963. PMid:20484884
» http://dx.doi.org/10.1159/000314963 -
19Podsiadlo D, Richardson S. The timed "up & go": a test of basic functional mobility for frail elderly persons. J Am Geriatr Soc. 1991;39(2):142-8. PMid:1991946.
-
20Swanenburg J, de Bruin ED, Uebelhart D, Mulder T. Falls prediction in elderly people: a 1-year prospective study. Gait Posture. 2010;31(3):317-21. http://dx.doi.org/10.1016/j.gaitpost.2009.11.013. PMid:20047833
» http://dx.doi.org/10.1016/j.gaitpost.2009.11.013 -
21Jolliffe IT. Principal Component Analysis. 2nd ed. New York: Springer; 2004.
-
22Astephen JL, Deluzio KJ. Changes in frontal plane dynamics and the loading response phase of the gait cycle are characteristic of severe knee osteoarthritis application of a multidimensional analysis technique. Clin Biomech (Bristol, Avon). 2005;20(2):209-17. http://dx.doi.org/10.1016/j.clinbiomech.2004.09.007. PMid:15621327
» http://dx.doi.org/10.1016/j.clinbiomech.2004.09.007 -
23Kirkwood RN, Brandon SC, Moreira BS, Deluzio KJ. Searching for stability as we age: the PCA-Biplot approach. Int J Stats Med Res. 2013;2(4):255-62.
-
24Kohler U, Luniak M. Data inspection using biplots. Stata J. 2005;5(2):208-23.
-
25De Wit L, Molas M, Dejaeger E, De Weerdt W, Feys H, Jenni W, et al. The use of a biplot in studying outcomes after stroke. Neurorehabil Neural Repair. 2009;23(8):825-30. http://dx.doi.org/10.1177/1545968309337137. PMid:19498014
» http://dx.doi.org/10.1177/1545968309337137 -
26Davidson PM, Digiacomo M, McGrath SJ. The feminization of aging: how will this impact on health outcomes and services? Health Care Women Int. 2011;32(12):1031-45. http://dx.doi.org/10.1080/07399332.2011.610539. PMid:22087593
» http://dx.doi.org/10.1080/07399332.2011.610539 -
27Coimbra AM, Ricci NA, Coimbra IB, Costallat LT. Falls in the elderly of the family health program. Arch Gerontol Geriatr. 2010;51(3):317-22. http://dx.doi.org/10.1016/j.archger.2010.01.010. PMid:20153535
» http://dx.doi.org/10.1016/j.archger.2010.01.010 -
28Gabriel KR. The biplot graphic display of matrices with application to principal component analysis. Biometrika. 1971;58(3):453-67. http://dx.doi.org/10.1093/biomet/58.3.453.
» http://dx.doi.org/10.1093/biomet/58.3.453 -
29Callisaya ML, Blizzard L, Schmidt MD, Martin KL, McGinley JL, Sanders LM, et al. Gait, gait variability and the risk of multiple incident falls in older people: a population-based study. Age Ageing. 2011;40(4):481-7. http://dx.doi.org/10.1093/ageing/afr055. PMid:21628390
» http://dx.doi.org/10.1093/ageing/afr055 -
30Bohannon RW. Reference values for the timed up and go test: a descriptive meta-analysis. J Geriatr Phys Ther. 2006;29(2):64-8. http://dx.doi.org/10.1519/00139143-200608000-00004. PMid:16914068
» http://dx.doi.org/10.1519/00139143-200608000-00004 -
31Hollman JH, McDade EM, Petersen RC. Normative spatiotemporal gait parameters in older adults. Gait Posture. 2011;34(1):111-8. http://dx.doi.org/10.1016/j.gaitpost.2011.03.024. PMid:21531139
» http://dx.doi.org/10.1016/j.gaitpost.2011.03.024 -
32Stalenhoef PA, Diederiks JP, Knottnerus JA, Kester AD, Crebolder HF. A risk model for the prediction of recurrent falls in community-dwelling elderly: a prospective cohort study. J Clin Epidemiol. 2002;55(11):1088-94. http://dx.doi.org/10.1016/S0895-4356(02)00502-4. PMid:12507672
» http://dx.doi.org/10.1016/S0895-4356(02)00502-4 -
33Kirkwood RN, Resende RA, Magalhães CM, Gomes HA, Mingoti SA, Sampaio RF. Application of principal component analysis on gait kinematics in elderly women with knee osteoarthritis. Rev Bras Fisioter. 2011;15(1):52-8. http://dx.doi.org/10.1590/S1413-35552011000100007. PMid:21519716
» http://dx.doi.org/10.1590/S1413-35552011000100007
Publication Dates
-
Publication in this collection
28 Nov 2014 -
Date of issue
Jan-Feb 2015
History
-
Received
12 Mar 2014 -
Reviewed
20 June 2014 -
Accepted
01 Aug 2014