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A Pilot Study for Reliability and Validity of Mini-Physical Performance Test for Chinese Male Elders
International Journal of Gerontology 6 (2012) 16e19
Contents lists available at SciVerse ScienceDirect
International Journal of Gerontology journal homepage: www.ijge-online.com
Original Article
A Pilot Study for Reliability and Validity of Mini-Physical Performance Test for Chinese Male Eldersq Da-Wei Chen*, Jin-Wen Chen, Wei Xu, Wei Liu, Wen-Jin Du, Hua-Jun Li Department of Neurology, Geriatric Institute, The General Hospital of Air Force PLA (the Chinese People’s Liberation Army), 30# Fucheng Street, Beijing 100142, China
a r t i c l e i n f o
s u m m a r y
Article history: Received 31 July 2010 Received in revised form 31 October 2010 Accepted 14 November 2010 Available online 23 March 2012
Background and purpose: Physical frailty may predict many adverse events, and it is important to identify a stable and easy clinical measurement to assess physical function for Chinese elders. Methods: We modified the mini-Physical Performance Test (PPT) of Wilkins et al by adding one-leg standing test and simulating the 15 meters timed walk with a 6 meters timed walk to construct the Chinese version mini-PPT (CM-PPT). A total of 170 elderly individuals were tested by CM-PPT and mini-mental state examination (MMSE). Twenty-three randomly chosen individuals were tested again by the same rater and another rater in a week, and the 15 meters timed walk and the Barthel index (BI) were also evaluated. Results: The Cronbach’s coefficient of CM-PPT was 0.868, and the testeretest and inter-rater reliability were 0.96 and 0.99, respectively (p < 0.001). When the diseases influencing PPT other than cognitive disorders were excluded, CM-PPT was associated with MMSE (r ¼ 0.420, p < 0.01) and age (r ¼ 0.649, p < 0.001) in 47 participants. CM-PPT was also correlated with BI (r ¼ 0.667, p < 0.001), while 65% of the participants acquired full marks for BI and only 9% of the participants did so for CM-PPT. Of the 170 participants, 31 had different results between tandem and one-leg positions (p < 0.001). Of these participants, 90% were only able to do tandem position and 10% were only able to do one-leg position. There was no difference between the scores in 6- and 15 meters timed walk (p ¼ 0.49). Conclusion: CM-PPT is a stable test and more sensitive than the BI. It is moderately associated with MMSE in the elderly without diseases influencing PPT other than cognitive disorders. Copyright Ó 2012, Taiwan Society of Geriatric Emergency & Critical Care Medicine. Published by Elsevier Taiwan LLC. All rights reserved.
Keywords: elderly, physical function, physical performance test, reliability, validity
1. Introduction Physical frailty, the decline in physical functions associated with aging, has been well described by a number of investigators1. It is widely recognized that physical frailty is associated with many adverse health-related events, such as falls, disability, hospitalization, and mortality2e5. Recently, physical frailty was also found to predict cognitive decline, incident mild cognitive impairment, and Alzheimer’s disease6e10. Therefore, it is important to identify a stable and easy clinical measurement to monitor physical function and early signs of physical frailty in the elderly. In addition, this measurement will be also useful in determining the potential efficacy of interventions such as exercises to prevent the decline in physical function11. In 1990, Reuben and Siu12 developed a nine-item performancebased measuredthe Physical Performance Test (PPT), a direct observational test which identified smaller limitations and slighter q All contributing authors declare no conflicts of interest. * Correspondence to: Dr Da-Wei Chen. E-mail address: [email protected] (D.-W. Chen).
declines in physical function than self-reported and observerestimation measures13e15; this test was modified later by Shah et al16. These two instruments had been shown limited in clinical application because of their length and need for additional equipment. Recently, Wilkins et al17 developed a mini-PPT that contained only four items by shortening the original PPT, and reported that it was able to correctly classify 85% or more of participants as functional or not, compared to the lengthier and more burdensome PPT. To date, no study has been conducted on PPT for Chinese elders, so we decided to construct a Chinese-language version of the miniPPT, and investigated its reliability and validity in order to supply Chinese clinicians an easy and convenient instrument to assess and monitor physical function in elderly individuals. 2. Participants and methods 2.1. Chinese version mini-PPT We modified the mini-PPT developed by Wilkins et al17 by adding one-leg standing (OLS) in standing static balance and
1873-9598/$ e see front matter Copyright Ó 2012, Taiwan Society of Geriatric Emergency & Critical Care Medicine. Published by Elsevier Taiwan LLC. All rights reserved. doi:10.1016/j.ijge.2011.09.022
Reliability and Validity of Mini-PPT
simulating the 15 meters timed walk with a 6 meters timed walk. First, this modification shortened the walking distance to make the test more suitable to limited clinical areas and was similar to that described by Wang et al8. Second, this modification strengthened the rater’s ability to measure the static balance because the OLS test had been shown as an important clinical tool in the assessment of balance in a static position18. The Chinese version mini-PPT (CMPPT) contains four physical performance tests: standing static balance, 6 meters timed walk (time of 3 meters forward and back), chair-stand time (time to sit in and rise from a chair with arms folded across their chest five times), and picking up a penny from the floor (placing a penny approximately 0.3 meters from the participant’s foot on the dominant side and measuring the time used by the participant to pick up the penny from the floor and stand up). Standing static balance also contains four actions: feet together (standing still with the feet together), semitandem (standing with the heel of one foot placed to the side of the first toe of the opposite foot), tandem (standing with the heel of one foot directly in front of the other foot), and one-leg position (standing unassisted on one leg with eyes open). The CM-PPT was administered by a trained research nurse. Because some studies have shown that rapid-paced walk (requiring greater functional reserve) appeared more sensitive in assessing the physical function than usual-paced walk19, 6 meters timed walk, chair-stand time, and picking up a penny from the floor were required to be done as quickly as possible. The 6 meters timed walk was completed with or without assistive devices, while chair-stand time, picking up a penny from floor, and standing static balance were done without assistive devices. Participants chose which foot went forward or was the supporting one. Each test was done twice, and the better result was used. Each test was scored from 0 to 4 points. The quartiles from the study population were used as cutoff points for scoring 6 meters timed walk, chair-stand time, and picking up a penny from the floor. Inability to walk was scored 0, and the rest were scored from 1 to 4 (where 1 ¼ slowest and 4 ¼ quickest). Standing static balance was scored by the ability to maintain the following positions: feet together for 10 seconds, semitandem for 10 seconds, tandem for 10 seconds and one-leg for 5 seconds. One score is given for each position. The CM-PPT score was the total score from the four physical tests and ranged from 0 to 16, with higher scores indicating better physical performance. 2.2. Participants Participants were recruited from 13 sanatoriums for retired cadres of Air Force PLA (the Chinese People’s Liberation Army). Eligibility criteria included the following: age 60 years or older, ability to follow a one-step command. Participants were excluded for the following criteria: enrollment in a hospice program of anticipated survival of less than 6 months, enrollment in a subacute or acute care program, inability to follow directions due to severe visual and hearing impairment or profound dementia. Participants provided written or verbal informed consent to participate in the study, which was approved by the institutional review committee. 2.3. Concurrent measures Because there is no “gold standard” in measuring physical function status and mobility, we used concurrent validation procedures. Barthel index (BI) was administered as a validated instrument to assess the participants’ level of independence in activities of daily living. It contains 10 items and provides scores from 0 to 2020. Mini-mental state examination (MMSE) was
17
designed to assess the participants’ cognitive function21,22. In order to compare the CM-PPT with the mini-PPT, the 15 meters timed walk was also tested. 2.4. Procedures Before the study, testers undertook a training course for verbal instruction, demonstration, administration, and scoring of CM-PPT given by the authors. There are 689 persons in 13 sanatoriums, and 170 participants meeting the criteria described above were tested using CM-PPT and MMSE in the General Hospital of Air Force PLA during the 2010 health examination. To examine the testeretest and inter-rater reliability of CM-PPT, 20% of the participants were randomly selected and asked to participate for the second testing of CM-PPT in a week; 30 participants agreed to be tested again. After a week, four participants were excluded because of an acute disease or accident (e.g., surgery) and three individuals were unavailable, which left 23 people to be tested again by the same tester and another tester. These two raters simultaneously and independently conducted the test with one tester administering the command and instructions while the other was observing at close range. These 23 participants were also further assessed using BI and 15 meters timed walk at the second testing of CM-PPT. 2.5. Statistical analysis The internal consistency of CM-PPT was evaluated by calculating Cronbach’s coefficient (alpha). Intraclass correlation coefficients were calculated to examine inter-rater and testeretest reliability for each item and total scores of CM-PPT. To evaluate concurrent validity, Pearson’s correlation coefficients were calculated. The difference between 15- and 6 meters timed walk scores was analyzed using paired t test. The difference between tandem and one-leg standing test were analyzed using McNemar test. Statistical significance was defined as p 0.05, and all statistical analyses were performed using the SPSS software version 12.0 (International Business Machines Corp. New Orchard Road, Armonk, New York). 3. Results The characteristics and diagnoses of 170 participants are shown in Table 1. Based on the quartiles from 170 participants, the cutoff points for scoring 6 meters timed walk, chair-stand time, and picking up a penny from the floor are shown in Table 2.
Table 1 Characteristics of 170 elderly individuals. Measure
M SD or number
Range
Age Sex (% male) CM-PPT MMSE Neoplasm (%) Anemia (%) Arthrositis (%) CRF (%) COPD (%) PD and related disease (%) Stroke (%) DM or IGT (%) HF (%) Participants without listed diseases (%)
81.5 6.8 y 157 (92.4) 9.4 4.7 25.9 4.0 33 (19.4) 12 (7.1) 8 (4.7) 16 (9.4) 11 (6.5) 11 (6.5) 43 (25.3) 52 (30.6) 21 (12.4) 47 (27.6)
60e95 y 0e16 10e30
CM-PPT ¼ Chinese version mini-PPT; COPD ¼ chronic obstructive pulmonary disease; CRF ¼ chronic renal failure; DM ¼ diabetes mellitus; HF ¼ heart failure; IGT ¼ impaired glucose tolerance; M ¼ mean; MMSE ¼ mini-mental state examination; PD ¼ Parkinson’s disease; SD ¼ standard deviation.
18
D.-W. Chen et al.
Table 2 Cutoff points for scoring 6 meters timed walk, chair-stand, and picking up tests.
Chair-stand 6 meters timed walk Picking up
0
1 (s)
2 (s)
3 (s)
4 (s)
Unable Unable Unable
>15 >11 >4
>12 >9 >3
>9 >7 >2
9 7 2
The characteristics of 23 randomly selected individuals are shown in Table 3. The Cronbach’s coefficient of CM-PPT was 0.868. The testeretest and inter-rater reliability of CM-PPT are shown in Table 4. When the participants with any disease listed in Table 1 were excluded, CM-PPT was associated with MMSE (r ¼ 0.420, p < 0.01) and age (r ¼ 0.649, p < 0.001) in 47 elderly individuals without any of the listed diseases (MMSE ¼ 26.1 3.2, age ¼ 80.5 7.0 years). In 23 randomly selected individuals, CM-PPT was correlated with BI (r ¼ 0.677, p < 0.001), while 15 participants (65%) acquired full marks for BI, and only two participants (9%) acquired full marks for CM-PPT. Of the 170 participants, 31 had different results between tandem position and one-leg position, and this difference was significant (p < 0.001). Twenty-eight participants (90%) were only able to do standing balance with tandem position, whereas three participants (10%) were only able to do standing balance with one-leg position. Among the 23 randomly selected individuals, the scores for 6- and 15 meters timed walk were 2.5 1.3 (0e4) and 2.4 1.2 (0e4), respectively, and there was no difference between them (p ¼ 0.49). 4. Discussion Our data showed that CM-PPT had high levels of internal consistency and inter-rater and testeretest reliability, which was similar to the results attained by the original PPT introduced by Reuben and Siu12. This suggests that CM-PPT is a reliable tool to assess and monitor physical function among Chinese elders even when conducted at different times and by different examiners. BI was administered as a validated instrument to assess the subjective level of independence in activities of daily living20. Our results showed that there was a strong association between CM-PPT and BI, indicating that both yield consistent results in assessing physical function. Compared with BI, CM-PPT had less ceiling effect in the same participants, so our results suggest that CM-PPT is more sensitive in evaluating physical function and recognizing early signs of decline in physical function than selfreported measures; these results are similar to those reported in other direct observational tests13e15. Considering that many factors, such as medical diseases, central and peripheral nervous diseases, or muscular and skeletal diseases, can influence physical function23e25, we excluded those participants with diabetes mellitus, impaired glucose tolerance, heart failure, chronic obstructive pulmonary disease, chronic renal failure, anemia, neoplasm, stroke, Parkinson’s disease, and arthrositis, and found that CM-PPT was positively correlated with MMSE Table 3 Characteristics of 23 randomly selected individuals. Measure
M SD or number
Range
Age Sex (% male) CM-PPT 6 meters timed walk 15 meters timed walk BI
80.8 7.2 y 23 (100) 9.8 4.6 9.75 5.60 S 18.52 12.07 S 18.1 3.9
60e92 y 0e16 0e25.87 s 0e57.94 s 4e20
BI ¼ Barthel index; CM-PPT ¼ Chinese version mini-PPT; M ¼ mean; SD ¼ standard deviation.
and negatively correlated with age in older persons without diseases influencing PPT other than cognitive disorders. A series of studies showed that decline in physical function was associated with cognitive impairment or the pathology of Alzheimer’s disease6e8,26, but the strength of association between performancebased measure and MMSE varied in different studies. The association found in this study was higher than that reported by Morala and Shiomi1 (r ¼ 0.31) but similar to that of Reuben et al12 (r ¼ 0.40 or 0.47 for seven- or nine-item PPT, respectively). This variance may be explained by the fact that the cognitive level of the participants may influence the strength of association between performancebased measure and MMSE since the average MMSE score in our sample is higher than that reported by Morala et al (MMSE ¼ 21.9) but similar to that of Reuben et al (MMSE ¼ 26.0). On one hand, performance-based measure may be sensitive in detecting the decline in physical function resulting from an earlier cognitive impairment6e8, and making it easy to produce the floor effect13e15. On the other hand, the participants with low MMSE may misunderstand the command of PPT, which can influence the results. The correlation between performance-based measure and age in this study was higher than that reported by Reuben and Siu12 (r ¼ 0.18 or e0.24 for seven- or nine-item PPT, respectively) and Morala et al23 (r ¼ 0.28) but similar to that presented by Binder et al27 (r ¼ 0.55). This difference may have resulted from the age distribution difference of participants, because the participants in this study and in the report of Binder et al are older than those studied by Reuben et al and Morala et al. Ostir et al25 found that 85-yearsolds had the lowest initial scores on the performance measure and larger slope decline than 65- to 74- and 75- to 84-year-olds, so the association between performance-based measure and age may be higher in older individuals. In addition, our participants may have shown greater decline in physical function resulting from sarcopenia or muscle loss of aging28 because they have less exercise or physical labor due to their special social status. Compared with the original PPT12, the mini-PPT developed by Wilkins et al17 is a brief (it consists of four physical performance tests and can be completed in less than 5 minutes) and convenient (only a penny and a chair are required) tool, but it has several limitations. In order to be suitable to limited clinical areas, we shortened the 15 meters timed walk to a 6 meters timed walk, but our results showed that there was no significant difference between these two scores. This suggests that shortening the distance does not influence the result of the timed walk test. We also modified the mini-PPT of Wilkins et al by adding OLS in standing static balance. Thus, the four items make the scoring easier and strengthen the rater’s ability to measure the static balance because the OLS test has been shown as an important clinical tool in assessing balance in a static position. In fact, our study also showed that there was a significant difference between tandem and one-leg standing results, and 90% of the participants with inconsistent results were not able to complete one-leg standing. These results indicate that greater balance ability is required for one-leg standing; in other words, one-leg standing is more sensitive in assessing balance ability than tandem standing. In a nutshell, compared with the mini-PPT of Wilkins et al, the CMPPT retains the same level of scores in timed walking after the walking distance is shortened, and is more sensitive in assessing balance. The limitations of this study must be noted. First, the sample size is not very large due to the limited time available during the health examination, and some participants for second testing had to be excluded because of an acute disease or accident or because they were unavailable, which lowers the power of this study. However, the examiners found CM-PPT easy to administer and interpret, and participants found the test simple to perform. This
Reliability and Validity of Mini-PPT
19
Table 4 The testeretest and inter-rater reliability of CM-PPT.
Testeretest (95% CI) Inter-rater (95% CI)
Standing static balance
Chair-stand
6 meters timed walk
Picking up
CM-PPT
0.93 0.83e0.97) 1.00
0.88 (0.74e0.95) 0.99 (0.96e0.99)
0.90 (0.78e0.96) 0.95 (0.89e0.98)
0.83 (0.64e0.92) 0.90 (0.77e0.96)
0.96 (0.91e0.98) 0.99 (0.97e0.99)
All data are p < 0.001. CI ¼ confidence interval; CM-PPT ¼ Chinese version mini-PPT.
makes further study with a much larger sample possible. Second, all of the study participants are male because our sample consisted of retired soldiers, which limits the generalization of our results. However, we have no reason to expect that the results would differ for women because Morala et al23 found that gender was not correlated with PPT. In summary, CM-PPT is a stable tool for the evaluation and monitoring of physical function among Chinese elders; it is more sensitive than the BI and moderately associated with MMSE among Chinese elders without diseases influencing PPT other than cognitive disorders. Not only is CM-PPT brief, convenient, and easy (as in the case of the mini-PPT of Wilkins et al), it is also more suitable to use in a clinical environment by shortening the walking distance and strengthens the rater’s ability to assess balance by adding in the one-leg standing test. Due to the small sample size and the fact that the study participants consisted of male retired soldiers, we need to enlarge our sample size and include women in future studies. In addition, we will investigate the factors that influence physical function and the effect of CM-PPT in predicting incident mild cognitive impairment and dementia. Acknowledgments This work was supported by grants from the Ministry of Sciences and Technology of the General Hospital of Air Force PLA (KZ2010019). We also thank the officer of healthcare management for retired cadres in the General Hospital of Air Force PLA. References 1. Morala D, Shiomi T. Assessing reliability and validity of physical performance test for the Japanese elderly. Phys Ther Sci. 2004;16:15e20. 2. Cesari M, Kritchevsky SB, Newman AB, et al. Added value of physical performance measures in predicting adverse health-related events: results from the health, aging and body composition study. J Am Geriatr Soc. 2009;57: 251e259. 3. Delbaere K, Van den Noortgate N, Bourgois J, et al. The physical performance test as a predictor of frequent fallers: a prospective community-based cohort study. Clin Rehabil. 2006;20:83e90. 4. Guralnik JM, Ferrucci L, Simonsick EM, et al. Lower-extremity function in persons over the age of 70 years as a predictor of subsequent disability. N Engl J Med. 1995;332:556e561. 5. Onder G, Penninx BW, Ferrucci L, et al. Measures of physical performance and risk for progressive and catastrophic disability: results from the women’s health and aging study. J Gerontol A Biol Sci Med Sci. 2005;60:74e79. 6. Boyle PA, Buchman AS, Wilson RS, et al. Physical frailty is associated with incident mild cognitive impairment in community-based older persons. J Am Geriatr Soc. 2010;5:248e255.
7. Buchman AS, Boyle PA, Wilson RS, et al. Frailty is associated with incident Alzheimer’s disease and cognitive decline in the elderly. Psychosom Med. 2007;69:483e489. 8. Wang L, Larson EB, Bowen JD, et al. Performance-based physical function and future dementia in older people. Arch Intern Med. 2006;166:1115e1120. 9. Rolland Y, Abellan van Kan G, Nourhashemi F, et al. An abnormal “one-leg balance” test predicts cognitive decline during Alzheimer’s disease. J Alzheimers Dis. 2009;16:525e531. 10. Eggermont LH, Gavett BE, Volkers KM, et al. Lower-extremity function in cognitively healthy aging, mild cognitive impairment, and Alzheimer’s disease. Arch Phys Med Rehabil. 2010;91:584e588. 11. King MB, Judge JO, Whipple R, et al. Reliability and responsiveness of two physical performance measures examined in the context of a functional training intervention. Phys Ther. 2000;80:8e16. 12. Reuben DB, Siu AL. An objective measure of physical function of elderly outpatients. The physical performance test. J Am Geriatr Soc. 1990;38: 1105e1112. 13. Brach JS, VanSwearingen JM, Newman AB, et al. Identifying early decline of physical function in community-dwelling older women: performance-based and self-report measures. Phys Ther. 2002;82(4):320e328. 14. Terret C, Albrand G, Moncenix G, et al. Karnofsky Performance Scale (KPS) or physical performance test (PPT)? That is the question. Crit Rev Oncol Hematol; 2010:23 (Epub ahead of print). 15. Rozzini R, Frisoni GB, Ferrucci L, et al. The effect of chronic diseases on physical function. Comparison between activities of daily living scales and the physical performance test. Age Ageing. 1997;26:281e287. 16. Shah KR, Carr D, Roe CM, et al. Impaired physical performance and the assessment of dementia of the Alzheimer type. Alzheimer Dis Assoc Disord. 2004;18:112e119. 17. Wilkins CH, Roe CM, Morris JC. A brief clinical tool to assess physical function: the mini-physical performance test. Arch Gerontol Geriatr. 2010;50:96e100. 18. Michikawa T, Nishiwaki Y, Takebayashi T, et al. One-leg standing test for elderly populations. J Orthop Sci. 2009;14:675e685. 19. Fitzpatrick AL, Buchanan CK, Nahin RL, et al. Associations of gait speed and other measures of physical function with cognition in a healthy cohort of elderly persons. J Gerontol A Biol Sci Med Sci. 2007;62:1244e1251. 20. Mahoney FI, Barthel DW. Functional evaluation: the Barthel index. Md State Med J. 1965;14:61e65. 21. Folstein MF, Folstein SE, McHugh PR. “Mini-mental state.” A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12:189e198. 22. Bleecker ML, Bolla-Wilson K, Kawas C, et al. Age-specific norms for the minimental state exam. Neurology. 1988;38:1565e1568. 23. Morala DT, Shiomi T, Maruyama H. Factors associated with the functional status of community-dwelling elderly. J Geriatr Phys Ther. 2006;29:101e106. 24. Wang L, van Belle G, Kukull WB, et al. Predictors of functional change: a longitudinal study of nondemented people aged 65 and older. J Am Geriatr Soc. 2002;50:1525e1534. 25. Ostir GV, Volpato S, Fried LP, et al. Reliability and sensitivity to change assessed for a summary measure of lower body function: results from the women’s health and aging study. J Clin Epidemiol. 2002;55:916e921. 26. Buchman AS, Schneider JA, Leurgans S, et al. Physical frailty in older persons is associated with Alzheimer disease pathology. Neurology. 2008;71:499e504. 27. Binder EF, Storandt M, Birge SJ, et al. The relation between psychometric test performance and physical performance in older adults. J Gerontol A Biol Sci Med Sci. 1999;54:M428eM432. 28. Nikoli c M, Bajek S, Bobinac D, et al. Aging of human skeletal muscles. Coll Anthropol. 2005;29:67e70.
Contents lists available at SciVerse ScienceDirect
International Journal of Gerontology journal homepage: www.ijge-online.com
Original Article
A Pilot Study for Reliability and Validity of Mini-Physical Performance Test for Chinese Male Eldersq Da-Wei Chen*, Jin-Wen Chen, Wei Xu, Wei Liu, Wen-Jin Du, Hua-Jun Li Department of Neurology, Geriatric Institute, The General Hospital of Air Force PLA (the Chinese People’s Liberation Army), 30# Fucheng Street, Beijing 100142, China
a r t i c l e i n f o
s u m m a r y
Article history: Received 31 July 2010 Received in revised form 31 October 2010 Accepted 14 November 2010 Available online 23 March 2012
Background and purpose: Physical frailty may predict many adverse events, and it is important to identify a stable and easy clinical measurement to assess physical function for Chinese elders. Methods: We modified the mini-Physical Performance Test (PPT) of Wilkins et al by adding one-leg standing test and simulating the 15 meters timed walk with a 6 meters timed walk to construct the Chinese version mini-PPT (CM-PPT). A total of 170 elderly individuals were tested by CM-PPT and mini-mental state examination (MMSE). Twenty-three randomly chosen individuals were tested again by the same rater and another rater in a week, and the 15 meters timed walk and the Barthel index (BI) were also evaluated. Results: The Cronbach’s coefficient of CM-PPT was 0.868, and the testeretest and inter-rater reliability were 0.96 and 0.99, respectively (p < 0.001). When the diseases influencing PPT other than cognitive disorders were excluded, CM-PPT was associated with MMSE (r ¼ 0.420, p < 0.01) and age (r ¼ 0.649, p < 0.001) in 47 participants. CM-PPT was also correlated with BI (r ¼ 0.667, p < 0.001), while 65% of the participants acquired full marks for BI and only 9% of the participants did so for CM-PPT. Of the 170 participants, 31 had different results between tandem and one-leg positions (p < 0.001). Of these participants, 90% were only able to do tandem position and 10% were only able to do one-leg position. There was no difference between the scores in 6- and 15 meters timed walk (p ¼ 0.49). Conclusion: CM-PPT is a stable test and more sensitive than the BI. It is moderately associated with MMSE in the elderly without diseases influencing PPT other than cognitive disorders. Copyright Ó 2012, Taiwan Society of Geriatric Emergency & Critical Care Medicine. Published by Elsevier Taiwan LLC. All rights reserved.
Keywords: elderly, physical function, physical performance test, reliability, validity
1. Introduction Physical frailty, the decline in physical functions associated with aging, has been well described by a number of investigators1. It is widely recognized that physical frailty is associated with many adverse health-related events, such as falls, disability, hospitalization, and mortality2e5. Recently, physical frailty was also found to predict cognitive decline, incident mild cognitive impairment, and Alzheimer’s disease6e10. Therefore, it is important to identify a stable and easy clinical measurement to monitor physical function and early signs of physical frailty in the elderly. In addition, this measurement will be also useful in determining the potential efficacy of interventions such as exercises to prevent the decline in physical function11. In 1990, Reuben and Siu12 developed a nine-item performancebased measuredthe Physical Performance Test (PPT), a direct observational test which identified smaller limitations and slighter q All contributing authors declare no conflicts of interest. * Correspondence to: Dr Da-Wei Chen. E-mail address: [email protected] (D.-W. Chen).
declines in physical function than self-reported and observerestimation measures13e15; this test was modified later by Shah et al16. These two instruments had been shown limited in clinical application because of their length and need for additional equipment. Recently, Wilkins et al17 developed a mini-PPT that contained only four items by shortening the original PPT, and reported that it was able to correctly classify 85% or more of participants as functional or not, compared to the lengthier and more burdensome PPT. To date, no study has been conducted on PPT for Chinese elders, so we decided to construct a Chinese-language version of the miniPPT, and investigated its reliability and validity in order to supply Chinese clinicians an easy and convenient instrument to assess and monitor physical function in elderly individuals. 2. Participants and methods 2.1. Chinese version mini-PPT We modified the mini-PPT developed by Wilkins et al17 by adding one-leg standing (OLS) in standing static balance and
1873-9598/$ e see front matter Copyright Ó 2012, Taiwan Society of Geriatric Emergency & Critical Care Medicine. Published by Elsevier Taiwan LLC. All rights reserved. doi:10.1016/j.ijge.2011.09.022
Reliability and Validity of Mini-PPT
simulating the 15 meters timed walk with a 6 meters timed walk. First, this modification shortened the walking distance to make the test more suitable to limited clinical areas and was similar to that described by Wang et al8. Second, this modification strengthened the rater’s ability to measure the static balance because the OLS test had been shown as an important clinical tool in the assessment of balance in a static position18. The Chinese version mini-PPT (CMPPT) contains four physical performance tests: standing static balance, 6 meters timed walk (time of 3 meters forward and back), chair-stand time (time to sit in and rise from a chair with arms folded across their chest five times), and picking up a penny from the floor (placing a penny approximately 0.3 meters from the participant’s foot on the dominant side and measuring the time used by the participant to pick up the penny from the floor and stand up). Standing static balance also contains four actions: feet together (standing still with the feet together), semitandem (standing with the heel of one foot placed to the side of the first toe of the opposite foot), tandem (standing with the heel of one foot directly in front of the other foot), and one-leg position (standing unassisted on one leg with eyes open). The CM-PPT was administered by a trained research nurse. Because some studies have shown that rapid-paced walk (requiring greater functional reserve) appeared more sensitive in assessing the physical function than usual-paced walk19, 6 meters timed walk, chair-stand time, and picking up a penny from the floor were required to be done as quickly as possible. The 6 meters timed walk was completed with or without assistive devices, while chair-stand time, picking up a penny from floor, and standing static balance were done without assistive devices. Participants chose which foot went forward or was the supporting one. Each test was done twice, and the better result was used. Each test was scored from 0 to 4 points. The quartiles from the study population were used as cutoff points for scoring 6 meters timed walk, chair-stand time, and picking up a penny from the floor. Inability to walk was scored 0, and the rest were scored from 1 to 4 (where 1 ¼ slowest and 4 ¼ quickest). Standing static balance was scored by the ability to maintain the following positions: feet together for 10 seconds, semitandem for 10 seconds, tandem for 10 seconds and one-leg for 5 seconds. One score is given for each position. The CM-PPT score was the total score from the four physical tests and ranged from 0 to 16, with higher scores indicating better physical performance. 2.2. Participants Participants were recruited from 13 sanatoriums for retired cadres of Air Force PLA (the Chinese People’s Liberation Army). Eligibility criteria included the following: age 60 years or older, ability to follow a one-step command. Participants were excluded for the following criteria: enrollment in a hospice program of anticipated survival of less than 6 months, enrollment in a subacute or acute care program, inability to follow directions due to severe visual and hearing impairment or profound dementia. Participants provided written or verbal informed consent to participate in the study, which was approved by the institutional review committee. 2.3. Concurrent measures Because there is no “gold standard” in measuring physical function status and mobility, we used concurrent validation procedures. Barthel index (BI) was administered as a validated instrument to assess the participants’ level of independence in activities of daily living. It contains 10 items and provides scores from 0 to 2020. Mini-mental state examination (MMSE) was
17
designed to assess the participants’ cognitive function21,22. In order to compare the CM-PPT with the mini-PPT, the 15 meters timed walk was also tested. 2.4. Procedures Before the study, testers undertook a training course for verbal instruction, demonstration, administration, and scoring of CM-PPT given by the authors. There are 689 persons in 13 sanatoriums, and 170 participants meeting the criteria described above were tested using CM-PPT and MMSE in the General Hospital of Air Force PLA during the 2010 health examination. To examine the testeretest and inter-rater reliability of CM-PPT, 20% of the participants were randomly selected and asked to participate for the second testing of CM-PPT in a week; 30 participants agreed to be tested again. After a week, four participants were excluded because of an acute disease or accident (e.g., surgery) and three individuals were unavailable, which left 23 people to be tested again by the same tester and another tester. These two raters simultaneously and independently conducted the test with one tester administering the command and instructions while the other was observing at close range. These 23 participants were also further assessed using BI and 15 meters timed walk at the second testing of CM-PPT. 2.5. Statistical analysis The internal consistency of CM-PPT was evaluated by calculating Cronbach’s coefficient (alpha). Intraclass correlation coefficients were calculated to examine inter-rater and testeretest reliability for each item and total scores of CM-PPT. To evaluate concurrent validity, Pearson’s correlation coefficients were calculated. The difference between 15- and 6 meters timed walk scores was analyzed using paired t test. The difference between tandem and one-leg standing test were analyzed using McNemar test. Statistical significance was defined as p 0.05, and all statistical analyses were performed using the SPSS software version 12.0 (International Business Machines Corp. New Orchard Road, Armonk, New York). 3. Results The characteristics and diagnoses of 170 participants are shown in Table 1. Based on the quartiles from 170 participants, the cutoff points for scoring 6 meters timed walk, chair-stand time, and picking up a penny from the floor are shown in Table 2.
Table 1 Characteristics of 170 elderly individuals. Measure
M SD or number
Range
Age Sex (% male) CM-PPT MMSE Neoplasm (%) Anemia (%) Arthrositis (%) CRF (%) COPD (%) PD and related disease (%) Stroke (%) DM or IGT (%) HF (%) Participants without listed diseases (%)
81.5 6.8 y 157 (92.4) 9.4 4.7 25.9 4.0 33 (19.4) 12 (7.1) 8 (4.7) 16 (9.4) 11 (6.5) 11 (6.5) 43 (25.3) 52 (30.6) 21 (12.4) 47 (27.6)
60e95 y 0e16 10e30
CM-PPT ¼ Chinese version mini-PPT; COPD ¼ chronic obstructive pulmonary disease; CRF ¼ chronic renal failure; DM ¼ diabetes mellitus; HF ¼ heart failure; IGT ¼ impaired glucose tolerance; M ¼ mean; MMSE ¼ mini-mental state examination; PD ¼ Parkinson’s disease; SD ¼ standard deviation.
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D.-W. Chen et al.
Table 2 Cutoff points for scoring 6 meters timed walk, chair-stand, and picking up tests.
Chair-stand 6 meters timed walk Picking up
0
1 (s)
2 (s)
3 (s)
4 (s)
Unable Unable Unable
>15 >11 >4
>12 >9 >3
>9 >7 >2
9 7 2
The characteristics of 23 randomly selected individuals are shown in Table 3. The Cronbach’s coefficient of CM-PPT was 0.868. The testeretest and inter-rater reliability of CM-PPT are shown in Table 4. When the participants with any disease listed in Table 1 were excluded, CM-PPT was associated with MMSE (r ¼ 0.420, p < 0.01) and age (r ¼ 0.649, p < 0.001) in 47 elderly individuals without any of the listed diseases (MMSE ¼ 26.1 3.2, age ¼ 80.5 7.0 years). In 23 randomly selected individuals, CM-PPT was correlated with BI (r ¼ 0.677, p < 0.001), while 15 participants (65%) acquired full marks for BI, and only two participants (9%) acquired full marks for CM-PPT. Of the 170 participants, 31 had different results between tandem position and one-leg position, and this difference was significant (p < 0.001). Twenty-eight participants (90%) were only able to do standing balance with tandem position, whereas three participants (10%) were only able to do standing balance with one-leg position. Among the 23 randomly selected individuals, the scores for 6- and 15 meters timed walk were 2.5 1.3 (0e4) and 2.4 1.2 (0e4), respectively, and there was no difference between them (p ¼ 0.49). 4. Discussion Our data showed that CM-PPT had high levels of internal consistency and inter-rater and testeretest reliability, which was similar to the results attained by the original PPT introduced by Reuben and Siu12. This suggests that CM-PPT is a reliable tool to assess and monitor physical function among Chinese elders even when conducted at different times and by different examiners. BI was administered as a validated instrument to assess the subjective level of independence in activities of daily living20. Our results showed that there was a strong association between CM-PPT and BI, indicating that both yield consistent results in assessing physical function. Compared with BI, CM-PPT had less ceiling effect in the same participants, so our results suggest that CM-PPT is more sensitive in evaluating physical function and recognizing early signs of decline in physical function than selfreported measures; these results are similar to those reported in other direct observational tests13e15. Considering that many factors, such as medical diseases, central and peripheral nervous diseases, or muscular and skeletal diseases, can influence physical function23e25, we excluded those participants with diabetes mellitus, impaired glucose tolerance, heart failure, chronic obstructive pulmonary disease, chronic renal failure, anemia, neoplasm, stroke, Parkinson’s disease, and arthrositis, and found that CM-PPT was positively correlated with MMSE Table 3 Characteristics of 23 randomly selected individuals. Measure
M SD or number
Range
Age Sex (% male) CM-PPT 6 meters timed walk 15 meters timed walk BI
80.8 7.2 y 23 (100) 9.8 4.6 9.75 5.60 S 18.52 12.07 S 18.1 3.9
60e92 y 0e16 0e25.87 s 0e57.94 s 4e20
BI ¼ Barthel index; CM-PPT ¼ Chinese version mini-PPT; M ¼ mean; SD ¼ standard deviation.
and negatively correlated with age in older persons without diseases influencing PPT other than cognitive disorders. A series of studies showed that decline in physical function was associated with cognitive impairment or the pathology of Alzheimer’s disease6e8,26, but the strength of association between performancebased measure and MMSE varied in different studies. The association found in this study was higher than that reported by Morala and Shiomi1 (r ¼ 0.31) but similar to that of Reuben et al12 (r ¼ 0.40 or 0.47 for seven- or nine-item PPT, respectively). This variance may be explained by the fact that the cognitive level of the participants may influence the strength of association between performancebased measure and MMSE since the average MMSE score in our sample is higher than that reported by Morala et al (MMSE ¼ 21.9) but similar to that of Reuben et al (MMSE ¼ 26.0). On one hand, performance-based measure may be sensitive in detecting the decline in physical function resulting from an earlier cognitive impairment6e8, and making it easy to produce the floor effect13e15. On the other hand, the participants with low MMSE may misunderstand the command of PPT, which can influence the results. The correlation between performance-based measure and age in this study was higher than that reported by Reuben and Siu12 (r ¼ 0.18 or e0.24 for seven- or nine-item PPT, respectively) and Morala et al23 (r ¼ 0.28) but similar to that presented by Binder et al27 (r ¼ 0.55). This difference may have resulted from the age distribution difference of participants, because the participants in this study and in the report of Binder et al are older than those studied by Reuben et al and Morala et al. Ostir et al25 found that 85-yearsolds had the lowest initial scores on the performance measure and larger slope decline than 65- to 74- and 75- to 84-year-olds, so the association between performance-based measure and age may be higher in older individuals. In addition, our participants may have shown greater decline in physical function resulting from sarcopenia or muscle loss of aging28 because they have less exercise or physical labor due to their special social status. Compared with the original PPT12, the mini-PPT developed by Wilkins et al17 is a brief (it consists of four physical performance tests and can be completed in less than 5 minutes) and convenient (only a penny and a chair are required) tool, but it has several limitations. In order to be suitable to limited clinical areas, we shortened the 15 meters timed walk to a 6 meters timed walk, but our results showed that there was no significant difference between these two scores. This suggests that shortening the distance does not influence the result of the timed walk test. We also modified the mini-PPT of Wilkins et al by adding OLS in standing static balance. Thus, the four items make the scoring easier and strengthen the rater’s ability to measure the static balance because the OLS test has been shown as an important clinical tool in assessing balance in a static position. In fact, our study also showed that there was a significant difference between tandem and one-leg standing results, and 90% of the participants with inconsistent results were not able to complete one-leg standing. These results indicate that greater balance ability is required for one-leg standing; in other words, one-leg standing is more sensitive in assessing balance ability than tandem standing. In a nutshell, compared with the mini-PPT of Wilkins et al, the CMPPT retains the same level of scores in timed walking after the walking distance is shortened, and is more sensitive in assessing balance. The limitations of this study must be noted. First, the sample size is not very large due to the limited time available during the health examination, and some participants for second testing had to be excluded because of an acute disease or accident or because they were unavailable, which lowers the power of this study. However, the examiners found CM-PPT easy to administer and interpret, and participants found the test simple to perform. This
Reliability and Validity of Mini-PPT
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Table 4 The testeretest and inter-rater reliability of CM-PPT.
Testeretest (95% CI) Inter-rater (95% CI)
Standing static balance
Chair-stand
6 meters timed walk
Picking up
CM-PPT
0.93 0.83e0.97) 1.00
0.88 (0.74e0.95) 0.99 (0.96e0.99)
0.90 (0.78e0.96) 0.95 (0.89e0.98)
0.83 (0.64e0.92) 0.90 (0.77e0.96)
0.96 (0.91e0.98) 0.99 (0.97e0.99)
All data are p < 0.001. CI ¼ confidence interval; CM-PPT ¼ Chinese version mini-PPT.
makes further study with a much larger sample possible. Second, all of the study participants are male because our sample consisted of retired soldiers, which limits the generalization of our results. However, we have no reason to expect that the results would differ for women because Morala et al23 found that gender was not correlated with PPT. In summary, CM-PPT is a stable tool for the evaluation and monitoring of physical function among Chinese elders; it is more sensitive than the BI and moderately associated with MMSE among Chinese elders without diseases influencing PPT other than cognitive disorders. Not only is CM-PPT brief, convenient, and easy (as in the case of the mini-PPT of Wilkins et al), it is also more suitable to use in a clinical environment by shortening the walking distance and strengthens the rater’s ability to assess balance by adding in the one-leg standing test. Due to the small sample size and the fact that the study participants consisted of male retired soldiers, we need to enlarge our sample size and include women in future studies. In addition, we will investigate the factors that influence physical function and the effect of CM-PPT in predicting incident mild cognitive impairment and dementia. Acknowledgments This work was supported by grants from the Ministry of Sciences and Technology of the General Hospital of Air Force PLA (KZ2010019). We also thank the officer of healthcare management for retired cadres in the General Hospital of Air Force PLA. References 1. Morala D, Shiomi T. Assessing reliability and validity of physical performance test for the Japanese elderly. Phys Ther Sci. 2004;16:15e20. 2. Cesari M, Kritchevsky SB, Newman AB, et al. Added value of physical performance measures in predicting adverse health-related events: results from the health, aging and body composition study. J Am Geriatr Soc. 2009;57: 251e259. 3. Delbaere K, Van den Noortgate N, Bourgois J, et al. The physical performance test as a predictor of frequent fallers: a prospective community-based cohort study. Clin Rehabil. 2006;20:83e90. 4. Guralnik JM, Ferrucci L, Simonsick EM, et al. Lower-extremity function in persons over the age of 70 years as a predictor of subsequent disability. N Engl J Med. 1995;332:556e561. 5. Onder G, Penninx BW, Ferrucci L, et al. Measures of physical performance and risk for progressive and catastrophic disability: results from the women’s health and aging study. J Gerontol A Biol Sci Med Sci. 2005;60:74e79. 6. Boyle PA, Buchman AS, Wilson RS, et al. Physical frailty is associated with incident mild cognitive impairment in community-based older persons. J Am Geriatr Soc. 2010;5:248e255.
7. Buchman AS, Boyle PA, Wilson RS, et al. Frailty is associated with incident Alzheimer’s disease and cognitive decline in the elderly. Psychosom Med. 2007;69:483e489. 8. Wang L, Larson EB, Bowen JD, et al. Performance-based physical function and future dementia in older people. Arch Intern Med. 2006;166:1115e1120. 9. Rolland Y, Abellan van Kan G, Nourhashemi F, et al. An abnormal “one-leg balance” test predicts cognitive decline during Alzheimer’s disease. J Alzheimers Dis. 2009;16:525e531. 10. Eggermont LH, Gavett BE, Volkers KM, et al. Lower-extremity function in cognitively healthy aging, mild cognitive impairment, and Alzheimer’s disease. Arch Phys Med Rehabil. 2010;91:584e588. 11. King MB, Judge JO, Whipple R, et al. Reliability and responsiveness of two physical performance measures examined in the context of a functional training intervention. Phys Ther. 2000;80:8e16. 12. Reuben DB, Siu AL. An objective measure of physical function of elderly outpatients. The physical performance test. J Am Geriatr Soc. 1990;38: 1105e1112. 13. Brach JS, VanSwearingen JM, Newman AB, et al. Identifying early decline of physical function in community-dwelling older women: performance-based and self-report measures. Phys Ther. 2002;82(4):320e328. 14. Terret C, Albrand G, Moncenix G, et al. Karnofsky Performance Scale (KPS) or physical performance test (PPT)? That is the question. Crit Rev Oncol Hematol; 2010:23 (Epub ahead of print). 15. Rozzini R, Frisoni GB, Ferrucci L, et al. The effect of chronic diseases on physical function. Comparison between activities of daily living scales and the physical performance test. Age Ageing. 1997;26:281e287. 16. Shah KR, Carr D, Roe CM, et al. Impaired physical performance and the assessment of dementia of the Alzheimer type. Alzheimer Dis Assoc Disord. 2004;18:112e119. 17. Wilkins CH, Roe CM, Morris JC. A brief clinical tool to assess physical function: the mini-physical performance test. Arch Gerontol Geriatr. 2010;50:96e100. 18. Michikawa T, Nishiwaki Y, Takebayashi T, et al. One-leg standing test for elderly populations. J Orthop Sci. 2009;14:675e685. 19. Fitzpatrick AL, Buchanan CK, Nahin RL, et al. Associations of gait speed and other measures of physical function with cognition in a healthy cohort of elderly persons. J Gerontol A Biol Sci Med Sci. 2007;62:1244e1251. 20. Mahoney FI, Barthel DW. Functional evaluation: the Barthel index. Md State Med J. 1965;14:61e65. 21. Folstein MF, Folstein SE, McHugh PR. “Mini-mental state.” A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res. 1975;12:189e198. 22. Bleecker ML, Bolla-Wilson K, Kawas C, et al. Age-specific norms for the minimental state exam. Neurology. 1988;38:1565e1568. 23. Morala DT, Shiomi T, Maruyama H. Factors associated with the functional status of community-dwelling elderly. J Geriatr Phys Ther. 2006;29:101e106. 24. Wang L, van Belle G, Kukull WB, et al. Predictors of functional change: a longitudinal study of nondemented people aged 65 and older. J Am Geriatr Soc. 2002;50:1525e1534. 25. Ostir GV, Volpato S, Fried LP, et al. Reliability and sensitivity to change assessed for a summary measure of lower body function: results from the women’s health and aging study. J Clin Epidemiol. 2002;55:916e921. 26. Buchman AS, Schneider JA, Leurgans S, et al. Physical frailty in older persons is associated with Alzheimer disease pathology. Neurology. 2008;71:499e504. 27. Binder EF, Storandt M, Birge SJ, et al. The relation between psychometric test performance and physical performance in older adults. J Gerontol A Biol Sci Med Sci. 1999;54:M428eM432. 28. Nikoli c M, Bajek S, Bobinac D, et al. Aging of human skeletal muscles. Coll Anthropol. 2005;29:67e70.