Abstract
Background
The uncertain health care situations, such as that created by the COVID-19 pandemic, has limited hospital access and facilitated a paradigm shift in health care toward an increased demand for standard home visits and community-based rehabilitation services, including by ambulatory individuals with spinal cord injury (SCI).
Objectives
This 6-month prospective study explored the validity and reliability of a single-time sit-to-stand (STSTS) test when used by primary health care (PHC) providers, including a village health volunteer, caregiver, individual with SCI, and health professional.
Methods
Eighty-two participants were assessed for the STSTS using four arm placement conditions (arms on a walking device, arms on knees, arms free by the sides, and arms crossed over the chest) and standard measures, with prospective fall data follow-up over 6 months. Thirty participants involved in the reliability study were also assessed and reassessed for the ability to complete the STSTS conditions by PHC providers.
Results
Outcomes of the STSTS test, except the condition with arms on a walking device, could significantly discriminate lower extremity muscle strength (LEMS) and mobility of the participants (rpb = −0.58 to 0.69) with moderate concurrent validity. Outcomes of the tests without using the arms also showed moderate to almost-perfect reliability (kappa = 0.754–1.000) when assessed by PHC raters.
Conclusion
The findings suggest the use of an STSTS with arms free by the sides as a standard practical measure by PHC providers to reflect LEMS and mobility of ambulatory individuals with SCI in various clinical, community, and home-based settings.
Keywords: clinical measures, community health care services, home visit, neurology, rehabilitation
Introduction
The uncertain health care situation, such as that created by the COVID-19 pandemic, has limited hospital access and facilitated a paradigm shift in health care toward an increased demand for standard home visits and community-based rehabilitation services, including by ambulatory individuals with spinal cord injury (SCI) who usually walk nonfunctionally and face a high risk of falls.1–3 In such services, primary health care (PHC) providers, including community health workers or village health volunteers (VHVs), community residents or caregivers (CGs), and health care professionals, need to work cooperatively to enable universal access and distribute equitable health care services to individuals’ homes and communities.4–6 Therefore, an appropriate simple and practical measure is needed in order for them to execute effective health-related activities.
Sit-to-stand (STS) is a fundamental daily activity and prerequisite for other daily activities such as standing and walking.7,8 However, the task is mechanically demanding and requires contributions from many body systems, such as sensorimotor functions, balance control, weight-bearing ability, and psychological status.7 Therefore, apart from being an important rehabilitation strategy, the difficulty in rising from a sitting position is also used as a predictor for falls, future disability, nursing home placement, increased utilization of hospital services, and mortality of many individuals, such as the elderly and individuals with dementia and stroke.9–12
Recently, a single-time sit-to-stand (STSTS) test, has been introduced in ambulatory individuals with SCI. This is the simplest method of STS measures; the outcome is classified as able or unable to stand without external assistance.13 The findings suggest the use of independent STS without hands as a screening measure to indicate the ability of walking at least with a single cane. However, existing evidence only reports the ability of STSTS in individuals with SCI with or without hands,13 whereas the available STS measures have applied various arm placements, including arms crossed over the chest, arms free by the sides, arms on the thighs or knees, and arms on an armrest or a walking device,7,13–15 which may affect outcomes of the test. The authors of this article hypothesized that the STSTS test is a valid and reliable measure among PHC providers. However, the psychometric properties of the test may be affected by the positions of the arms while the individual is performing the STSTS. Thus, this study investigated the validity of the STSTS test when assessed in four arm placement conditions (i.e., arms crossed over the chest, arms free by the sides, arms on the knees, and arms on a walking device) as compared to data from standard measures for sensory scores, lower extremity motor strength (LEMS), and mobility. This study also assessed the rater and test-retest reliability of the STSTS test when used by PHC providers, including a VHV, CG, individual with SCI, and health care professional. The validity and reliability data of the present study would suggest an appropriate method of STSTS to be used as a standard measure for ambulatory individuals with SCI among PHC providers in various clinical, community, and home settings.
Methods
Participants
This 6-month prospective study was conducted in ambulatory individuals with incomplete SCI from a tertiary rehabilitation center and communities. The inclusion criteria were age at least 18 years with a body mass index (BMI) of 18.5 to 29.9 kg/m2 and having motor incomplete SCI from traumatic or nontraumatic causes as determined using the criteria from the American Spinal Cord Injury Association Impairment Scale (AIS C and D).16 Eligible participants also needed the ability to stand up from a chair with or without hands and to walk with or without a walking device for at least 10 m continuously. Ambulatory individuals with SCI were excluded if they presented any signs and symptoms that could affect the ability to perform the measurements in this study, such as having pain in the musculoskeletal system with an intensity of more than 5 out of 10 on a numeric pain rating scale, joint deformities affecting mobility, other neurological disorders such as having brain function disorders, and unstable medical conditions. The sample size for a validity study was derived from a major study (N = 82),17 and the sample size for a reliability study was suggested to be at least 30 participants.18 The eligible participants signed an informed consent document that was approved by the institutional ethics committee (HE 601349) prior to participation in the study.
Research protocols
On the first day, the participants were interviewed and assessed for demographics and SCI characteristics, including postinjury time, cause of injury, and level and severity of SCI following the AIS protocols.16 Then, all participants were assessed for their ability to perform STSTS using four arm placement conditions in random order with lower limb loading assessment while the test was being performed. STSTS ability of the first 30 participants was recorded for further analysis on the rater reliability. Then the participants were assessed for the standard measures by an experienced rater in a random order to verify the validity of the STSTS outcomes. During the tests, participants had a lightweight safety belt fastened around their waist with an assessor by their side to ensure safety and the accuracy of the tests. Subsequently, the participants were monitored for fall data every month for 6 months. The details of the tests are as follows.
STSTS test and lower limb loading during the test
Previous studies reported that some ambulatory individuals with SCI used upper limb contribution via walking devices even though they did not actually need it.13,19,20 Therefore, this study assessed the amount of lower limb loading during STSTS measures to confirm their actual ability. The participants sat on a standard armless chair with their back upright against the chair’s backrest, hip flexion at 90 degrees, and their feet flat on digital load cells (four half-bridge weigh sensors with a standard calibration method based on UKASLAB 14: 2006, an accuracy up to 0.1 kg, and a measurement uncertainty of ±0.082 kg/side; mini-patent application number 2203001596) at 10 cm behind their knees. Then they stood up from the chair while positioning their arms in the four conditions in random order: arms on a walking device, arms on their knees, arms hanging freely by their sides, and arms crossed over their chest.13,17,21 The tests were recorded as “able” if the participants could safely rise from the chair without using their arms and with no more than contact guarding assistance and “unable” if they were unable to rise from the chair without using their arms and/or with more than contact guarding assistance. The participants who successfully performed the test for the able criteria in at least two of three trials were categorized into the “pass” group; otherwise, they were arranged in the “fail” group.13,21,22 The average lower limb loading data over the three trials were also recorded.13
Standard measures
Lower extremity muscle strength. The participants were assessed for muscle strength of the joints of lower extremities, including hip (flexors, extensors, abductors, and adductors), knee (flexors and extensors), and ankle (dorsiflexors and plantarflexors) using a manual muscle test. The strength of each muscle group was graded on a 12-point scale, including 0, 1, 2−, 2, 2+, 3−, 3, 3+, 4−, 4, 4+, and 5. The outcomes were converted into scores from 0 to 11, and the total LEMS score was 176.23
10-meter walk test. The 10-meter walk test (10MWT) represents a walking speed that is considered a surrogate for the overall quality of gait and motor function. The participants walked at a comfortable pace along a 10-m walkway with or without a walking device. The time required to cover the middle 4-m walkway was recorded. The average time required in the three trials was converted to a walking speed.24
Walking Index for Spinal Cord Injury II. This measure quantifies walking ability of individuals with SCI according to distance, physical assistance, lower extremity bracing, and ambulatory aids using 21 ordinal scales, from 0 to 20. The outcomes correlate with other scales necessary for independence, including the Spinal Cord Independence Measure (SCIM) and the Functional Independence Measure (FIM), in individuals with SCI.25 The outcomes of this measure were recorded while the participants completed the 10MWT.
Timed Up and Go test. The Timed Up and Go (TUG) test was designed to reflect mobility, dynamic balance ability, and fall risk. The test recorded the time that the participants stood up from a standard armrest chair, walked around a traffic cone located 3 m from the chair, and returned to sit down on the chair at a maximum and safe speed with or without a walking device.26 The average time over three trials was used for data analysis.
6-minute walk test. The outcomes of this test reflect the functional endurance required for community ambulation. The participants walked along a rectangular walkway for as far as possible within 6 minutes, taking a period of rest as needed. They were informed of the time left in the test every minute and encouraged to continue in a good manner. The distance covered after 6 minutes was recorded.27
Fall data
After completing the tests in this study, participants were given a fall diary to record the fall data and related events daily at home.2 The researcher (L.K.) phoned the participants every month for 6 months to gather the monthly fall data (i.e., fall event, date, time, place, circumstances, and consequences of the fall), with data confirmation from the caregivers or relatives. A fall was defined as an unplanned, unexpected, or unintentional event that occurred while changing postures, standing, or walking that resulted in a person coming to rest on the ground or other lower supporting surface.2,3
Reliability tests
The reliability of the STSTS test was assessed in the first 30 participants with SCI by four PHC raters, including a health professional (an expert, a physical therapist [PT] who had experience in using the STSTS test over at least 4 years), a village health volunteer (VHV; 40 years old, graduated a secondary school with 5 years of working experience), a caregiver (CG; 49 years old and a family member of an individual with SCI), and an ambulatory patient with SCI (51 years old with 3 years postinjury). The details of the reliability tests are as follows.
Rater reliability
All three PHC members (VHV, CG, and patient) were trained by the expert regarding the methods of administering the STSTS test and recording the outcomes. Then they underwent a practice session of approximately 30 minutes. Subsequently, all raters assessed the outcomes of each STSTS condition from the video files, with an interval of a week between the first and second sessions. Data from both sessions of each rater were used to reflect intrarater reliability, and data from all raters in the first session were used to represent the interrater reliability of each STSTS method.18
Test-retest reliability
The ability to complete each method of STSTS of the first 30 participants was reassessed by the expert (PT), with a 7-day interval between sessions. Data from both sessions were used to analyze the test-retest reliability of each STSTS method.18
Data analysis
The Shapiro-Wilk test was used to estimate the normality of the data. Descriptive statistics were applied to explain the demographics and SCI characteristics of the participants, and the findings of the study. The independent samples t test or the Mann-Whitney U test was used to compare the outcomes of standard measures (including the sensory scores, LEMS, functional mobility, and lower limb loading during STS) between the pass and fail groups, (i.e., the discriminative validity of each arm placement condition). The point-biserial correlation coefficient (rpb) was applied to indicate the concurrent validity of the STSTS outcomes and the standard measures. The correlation strength was interpreted as modest (0.30–0.49), moderate (0.50–0.69), and strong (>0.70).28 The kappa statistic was used to report the reliability (agreement) for the dichotomization (pass or fail) of the STSTS outcomes. The consistency of the agreement was defined as none (0–0.20), minimal (0.21–0.39), weak (0.40–0.59), moderate (0.60–0.79), strong (0.80–0.90), and almost perfect (> 0.90).29 The level of significant difference was set to a p value of less than .05.
Results
Participants’ demographics
Eighty-two middle-aged ambulatory participants with incomplete SCI, mostly males, participated in this study. The first 30 participants were also involved in the reliability study (Table 1). Most of them were at a chronic stage and used a walking device (primarily a standard walker) on a daily basis (Table 1). Sixty participants were monitored monthly for the fall data because this variable was included after initiation of the study. Nearly half of the participants who passed and failed the STSTS test experienced falls (1–3 falls/participant) without serious consequences.
Table 1.
Demographics and spinal cord injury characteristics of the participants
| Variable | Reliability tests (n = 30) | All participants (n = 82) |
|---|---|---|
| Age, years | 49.7 ± 15.2 (44.1–55.4) | 51.8 ± 14.3 (48.7–54.9) |
| Body mass index, kg/m2 | 23.2 ± 3.68 (21.8–24.5) | 22.6 ± 3.47 (21.8–23.3) |
| Postinjury time, months | 89.8 ± 80.6 (59.7–119) | 85.6 ± 79.8 (68.1–103) |
| Gendera: male | 24 (80%) | 69 (84%) |
| Stage of injurya: chronic | 28 (93%) | 73 (89%) |
| Cause of injurya: nontraumatic | 17 (57%) | 42 (51%) |
| Level of injurya: incomplete paraplegia | 20 (67%) | 55 (67%) |
| AISa: D | 20 (67%) | 64 (78%) |
|
| ||
| Using a walking device | ||
|
| ||
| Walker | 10 (33%) | 31 (38%) |
| Crutches | 2 (7%) | 8 (10%) |
| Cane | 7 (23%) | 14 (17%) |
| None | 11 (37%) | 29 (35%) |
Note: Data are presented as mean ± SD (95% confidence interval) or n (%). AIS = American Spinal Injury Association Impairment Scale.
These variables were categorized according to the following criteria: gender: male/female; cause: nontraumatic/traumatic; level of injury: incomplete paraplegia/incomplete tetraplegia; stage of injury: subacute (≤12 months)/chronic (>12 months); AIS class: C/D.
Findings of the study
Discriminative and concurrent validity of the STSTS
All 82 participants were able to complete the STSTS test with their arms on a walking device (pass), but their maximum lower limb loading was significantly lower than that of the other arm placement conditions (p < .001; Table 2, Figure 1). Conversely, 54 to 57 participants passed the STSTS test in the other conditions, and the remaining participants failed. Those who passed had the average LEMS score of 139, 10MWT of 0.68 m/s, WISCI II score of 18, and 6MWT of 228 m (Table 2). The data of these standard measures of those who passed were significantly better than those who failed in the test (p < .001), except for the fall data (p > .05; Table 2). The ability to execute these conditions (pass or fail) also showed moderate-to-good correlation with the LEMS scores (rpb = 0.65–0.69, p < .001) and all functional mobility measures, including 10MWT, WISCI II, TUG test, and 6MWT (rpb = −0.58 to 0.62, p < .001; Table 3).
Table 2.
Sensory and lower extremity muscle strength scores and mobility measures of participants in four arm placement conditions of the single-time sit-to-stand test (STSTS) test
| Variable | STSTS when tested with: | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||
| Arms on a walking device | Arms on knees | Arms by sides | Arms crossed over the chest | |||||||
|
| ||||||||||
| Able (n =82) | Fail (n = 25) | Pass (n = 57) | p b | Fail (n = 27) | Pass (n = 55) | p b | Fail (n = 28) | Pass (n = 54) | p b | |
| Sensory scores | ||||||||||
| Light touch (112) a | 95.5 ± 18.2 (91.5–99.5) | 95.0 ± 22.7 (85.7–104) | 95.7 ± 16.1 (91.5–99.9) | .979 | 95.0 ± 21.9 (86.3–104) | 95.7 ± 16.2 (91.4–100) | .976 | 95.0 ± 21.6 (86.7–103) | 95.8 ± 16.4 (91.3–100) | .852 |
| Pin prick (112) a | 95.0 ± 17.2 (91.2–98.8) | 94.7 ± 22.3 (85.5–104) | 95.2 ± 14.6 (91.3–99.0) | .751 | 94.6 ± 21.6 (86.1–103) | 95.2 ± 14.8 (91.2–99.2) | .836 | 95.0 ± 21.3 (86.8–103) | 95.0 ± 14.9 (91.0–99.1) | .695 |
| LEMS (176) a | 124 ± 32.7 (116–131) | 89.8 ± 27.1 (78.7–101) | 139 ± 22.3 (133–144) | <.001 | 93.3 ± 28.9 (81.9–105) | 139 ± 22.7 (132–145) | <.001 | 93.7 ± 28.4 (82.7–105) | 139 ± 22.4 (133–145) | <.001 |
| 10MWT, m/s | 0.55 ± 0.33 (0.47–0.62) | 0.25 ± 0.11 (0.21–0.30) | 0.68 ± 0.31 (0.60–0.76) | <.001 | 0.27 ± 0.13 (0.22–0.32) | 0.68 ± 0.31 (0.60–0.77) | <.001 | 0.26 ± 0.13 (0.22–0.32) | 0.69 ± 0.30 (0.61–0.78) | <.001 |
| WISCI II (20) a | 16.7 ± 3.25 (15.9–17.4) | 13.7 ± 1.60 (13.0–14.3) | 18.0 ± 2.89 (17.2–18.7) | <.001 | 13.9 ± 1.89 (13.2–14.7) | 18.0 ± 2.93 (17.2–18.8) | <.001 | 13.9 ± 1.9 (13.2–14.7) | 18.1 ± 2.87 (17.3–18.9) | <.001 |
| TUG test, s | 29.2 ± 20.9 (24.6–33.8) | 47.5 ± 21.9 (38.4–56.6) | 21.2 ± 14.6 (17.3–25.1) | <.001 | 46.3 ± 21.9 (37.6–54.9) | 21.0 ± 14.4 (16.7–24.8) | <.001 | 47.4 ± 22.3 (38.7–56.0) | 20.0 ± 21.4 (16.4–23.2) | <.001 |
| 6MWT, m | 184 ± 117 (158–209) | 89.7 ± 36.9 (74.4–105) | 225 ± 116 (194–256) | <.001 | 95.4 ± 44.6 (77.8–113) | 228 ± 117 (196–259) | <.001 | 93.7 ± 44.6 (76.4–111) | 231 ± 115 (199–262) | <.001 |
Table 2.
Sensory and lower extremity muscle strength scores and mobility measures of participants in four arm placement conditions of the single-time sit-to-stand test (STSTS) test (cont.)
| Variable | STSTS when tested with: | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
|
| ||||||||||
| Arms on a walking device | Arms on knees | Arms by sides | Arms crossed over the chest | |||||||
|
| ||||||||||
| Able (n =82) | Fail (n = 25) | Pass (n = 57) | p b | Fail (n = 27) | Pass (n = 55) | p b | Fail (n = 28) | Pass (n = 54) | p b | |
| Sensory scores | ||||||||||
| Maximal LLL-STS, % body weight | 101 ± 16 (99.1–103) | 79.6 ± 21.7 (66.5–92.8) | 110 ± 5.59cW (108–112) | <.001 | 71.2 ± 24.0 (56.7–85.7) | 110 ± 6.0cW (108–112) | <.001 | 72.3 ± 21.7 (59.1–85.4) | 110 ± 6.0cW (108–112) | <.001 |
| Fall: yes, n (%)d (n = 60) | 29 (48) | 9 (47) | 20 (49) | .919 | 11 (52) | 18 (46) | .645 | 11 (52) | 18 (46) | .645 |
Note: The data are presented using mean ± SD (95% confidence interval). 6MWT = 6-minute walk test; 10MWT = 10-meter walk test; Fail = participants who were unable to rise from a standard armless chair without using their arms and/or with more than contact guarding assistance; LEMS = lower extremity muscle strength; LLL-STS = lower limb loading during sit-to-stand; Pass = participants who could safely rise from a standard armless chair without using their arms and with no more than contact guarding assistance; TUG = Timed Up and Go test; WISCI II = Walking Index for Spinal Cord Injury II.
The total scores of each variable.
The differences between the able and unable groups in each condition were analyzed using the Mann-Whitney U test.
The differences among the four arm placement condition were analyzed using the the Kruskal-Willis test and every pairwise comparison was analyzed using the Mann-Whitney U test.
The differences between the participants who were pass and fail in three arms conditions using the chi-square test.
Indicates the condition(s) with significant differences from arms on a walking device (p < .001).
Figure 1.
Lower limb loading during sit-to-stand (STS) of an individual with spinal cord injury (y axis) who could perform the STS with four arm placement conditions.
Table 3.
The correlation between the data of the four arm placement conditions of the single-time sit-to-stand (STSTS) test and standard measures
| Variable | STSST [fail (n)/pass (n)] when tested with: | |||
|---|---|---|---|---|
|
| ||||
| Arms on a walking device (0/82) | Arms on knees (25/57) | Arms by sides (27/55) | Arms crossed over the chest (28/54) | |
| Sensory scores | ||||
| Light touch | N/A | 0.01 | 0.01 | 0.02 |
| Pin prick | N/A | 0.03 | 0.02 | 0.01 |
| LEMS | N/A | 0.69a | 0.65a | 0.66a |
| 10MWT | N/A | 0.60a | 0.59a | 0.62a |
| WISCI II | N/A | 0.62a | 0.59a | 0.61a |
| TUG test | N/A | −0.58a | −0.57a | −0.62a |
| 6MWT | N/A | 0.54a | 0.54a | 0.61a |
Note: The data are presented using point-biserial correlations (rpb). 6MWT = 6-minute walk test; 10MWT = 10-meter walk test; LEMS = lower extremity muscle strength; N/A = not available; TUG test = Timed Up and Go test; WISCI II = Walking Index for Spinal Cord Injury II.
Indicates significant correlation (p < .001).
Reliability of the STSTS test
All 30 participants were able to complete the STSTS test with their arms on a walking device. Thus they were arranged into the pass group, and there were no kappa coefficients for this condition (Table 4). By contrast, some participants (n = 8–10) were unable to complete the test in other arm placement conditions (Table 4). The STSTS outcomes in these three conditions showed an almost perfect intrarater reliability for a VHV, CG, patient, and expert (kappa = 0.918–1.000). In addition, STSTS outcomes of these conditions when rated by the VHV, CG, and patient showed a strong to almost perfect interrater reliability as compared with the expert (kappa = 0.754–1.000). Similarly, the outcomes of these STSTS conditions showed strong to almost perfect test-retest reliability when rated by the expert (kappa = 0.842–1.000). Of all STSTS conditions assessed in this study, arms by the sides showed the most perfect intrarater, interrater, and test-retest reliability (Table 4).
Table 4.
Reliability of the single-time sit-to-stand (STSTS) test in four arm placement conditions
| Rater | STSTS [fail (n)/pass (n)] when tested with: | |||
|---|---|---|---|---|
|
| ||||
| Arms on a walking device | Arms on knees | Arms by the sides | Arms crossed over the chest | |
| Intrarater reliability | ||||
|
| ||||
| Village health volunteer (VHV) | ||||
|
| ||||
| Session 1 | 0/30 | 9/21 | 10/20 | 9/21 |
| Session 2 | 0/30 | 9/21 | 10/20 | 9/21 |
| kappa | N/A | 1.000 | 1.000 | 1.000 |
|
| ||||
| Caregiver (CG) | ||||
|
| ||||
| Session 1 | 0/30 | 8/22 | 10/20 | 20/10 |
| Session 2 | 0/30 | 10/20 | 10/20 | 20/10 |
| kappa | N/A | 0.842 | 1.000 | 0.850 |
|
| ||||
| Patient | ||||
|
| ||||
| Session 1 | 0/30 | 8/22 | 10/20 | 9/21 |
| Session 2 | 0/30 | 9/21 | 10/20 | 9/21 |
| kappa | N/A | 0.918 | 1.000 | 1.000 |
|
| ||||
| Expert | ||||
|
| ||||
| Session 1 | 0/30 | 9/21 | 10/20 | 10/20 |
| Session 2 | 0/30 | 9/21 | 10/20 | 10/20 |
| kappa | N/A | 1.000 | 1.000 | 1.000 |
|
| ||||
| Interrater reliability | ||||
|
| ||||
| VHV vs. expert | N/A | 0.841 | 1.000 | 0.918 |
| CG vs. expert | N/A | 0.754 | 1.000 | 0.842 |
| Patient vs. expert | N/A | 0.754 | 1.000 | 0.918 |
|
| ||||
| Test-retest reliability | ||||
|
| ||||
| Session 1 | 0/30 | 10/20 | 10/20 | 10/20 |
| Session 2 | 0/30 | 8/22 | 10/20 | 10/20 |
| kappa | N/A | 0.842 | 0.850 | 1.000 |
Note: Fail = participants who were unable to rise from a standard armless chair without using their arms and/or with more than contact guarding assistance; N/A = not available; Pass = participants who could safely rise from a standard armless chair without using their arms and with no more than contact guarding assistance.
Discussion
Our prior findings13 suggested the use of pass and fail on an STSTS test by a rehabilitation professional without the suggestion for an optimal form and the ability of PHC members to use the test. The present findings further indicate that participants who passed in all STSTS conditions, except the one with arms on a walking device, had good LEMS (nearly 80% of the total scores) and mobility (Table 2). The outcomes of these conditions (pass and fail) could significantly discriminate (p < .001, Table 2) with moderate-to-good concurrent validity (rpb = −0.58 to 0.69; Table 3) as compared with LEMS and mobility measures. Moreover, with its simplicity, the STSTS outcomes of these three arm placement conditions are reliable when used by PHC providers, particularly in the condition of arms by the sides (Table 3).
The contribution of the arms while performing STSTS (i.e., performing the test with arms on a walking device) significantly reduces the task demands of the lower extremities (p < .001; Figure 1, Table 2). Thus, all participants could successfully rise up from the chair even though some of them actually had poor lower limb loading, LEMS, and functional mobility (Figure 1 and Table 2). Arborelius et al.30 reported that only 50% of the extension moment at the hips is needed when performing STS using hands. Alexander et al.31 found that when older adults were allowed to place their hands on an armrest, the proportion of those who were unable to rise from a standard chair decreased from 32% to 1%. Consequently, the ability to complete STSTS with arms on a walking device was unable to represent the LEMS and functional mobility of ambulatory individuals with SCI, and this condition had no reliability data.
Conversely, STSTS in the other three arm placement conditions, including arms on knees, arms free by the sides, and arms crossed over the chest, minimized the upper limb contribution. Such ability requires dynamic balance control to transfer the body’s center of mass from a stable three-point base of support while sitting to a less stable two-point base of support while standing.17,21 In these conditions, lower limb muscles need to develop adequate lower limb force and joint torque8 and lower limb loading significantly greater than that in the arms on a walking device condition (p < .001; Table 2, Figure 1). Consequently, the findings indicate that participants who passed in these STSTS conditions had an average LEMS score of 139 or nearly 80% of the total scores, with average lower limb loading or weight-bearing ability of 110% of the body weight (Table 2). These findings were associated with the WISCI II scores; the participants who passed in these conditions had an average WISCI II score of 18 or the ability of walking without a walking device.25 Khuna et al.13 also found the significant correlation between the ability of STSTS without hands and the ability of walking with at least a single cane (p < .01).
The present study further suggests that participants who passed an STSTS test had a walking speed (10MWT) more than 0.6 m/s, which is regarded as the ability of functional walking, and they could walk longer than 200 m in 6 minutes (6MWT), which is used to identify those with a high risk of mortality (Table 2).24,27 In contrast, participants who failed in these three arm placement conditions of the STSTS test had significantly poorer outcomes in all standard measures than those who passed (p < .001; Table 2). These findings confirm discriminative validity of the STSTS outcomes for LEMS and mobility measures. Khuna et al.13 similarly found that the LEMS, lower limb loading, and balance control ability (as measured using the TUG test) of ambulatory individuals who performed the STSTS test without hands were significantly better than of those who needed hands while executing the test.
Nonetheless, the lack of significant differences of the fall rates between participants who passed and failed in these three STSTS conditions (Table 2) may suggest effects of physical activity reduction and the number of participants in each group. This study was conducted during the COVID-19 pandemic, when most participants reduced their physical activities and spent most time at home. Moreover, the fall variable was included after initiation of the study, and there were only 60 participants in this variable. Only 20 participants failed in STSTS, and 9 to 11 of these participants reported falls. These findings suggest the need for a further study to confirm the ability of STSTS outcomes to detect falls in ambulatory individuals with SCI.
The present findings further found the significant correlation between the outcomes of conditions assessed without hands and standard measures, suggesting their concurrent validity to reflect LEMS and functional mobility necessary for walking, balance, fall risk, and independence of ambulatory individuals with SCI (rpb = −0.58 to 0.69; Table 3). Previous studies reported that the ability to complete a five-times STS without hands required the ability of weight-bearing, balance control, and LEMS and contribution from many body systems (i.e., sensory and psychological status similar to those required for independent walking).6–9,14,15,17,22
STS is a simple activity whereby the outcomes are categorized into pass and fail; it is easy for health professionals and laypeople to assess performance after being properly trained for the methods of administration and outcome recording. Thus, outcomes of the test showed almost perfect reliability among PHC raters (Table 4). The slight differences in the findings among the conditions could be attributed to the confusion and the task demands. The condition of arms on the knees enabled the participants to push their arms against their thighs/knees. However, many participants complained about the confusion in arm placement, that is, where to place their hands and how much they should push, given that all the participants had bilateral sensorimotor impairments that distorted their confidence to push both hands on the knees. Thus the STSTS test with arms on the knees showed the lowest rater and test-retest reliability (Table 4). Conversely, the condition of arms crossed over the chest raised the position of the body’s center of mass while restricting the upper limb contribution for body balance when changing from a stable three-point base of support to a less stable two-point base of support.32 Thus, this condition was the most difficult for the participants and resulted in the least number of participants who passed in the test (n = 54; Table 2). The most difficult task also led to the most reliable outcomes over time (kappa = 1.000; Table 4). By contrast, participants suggested that the condition of arms hanging naturally by the sides helped their body balance, thus they could perform the task optimally and helped the raters to determine the outcomes of the test easily. Therefore, the rater reliability of this condition was slightly higher than the other conditions (Table 4).
The present findings are particularly important nowadays; there is a need for a practical strategy to deliver standard health care services to individuals’ homes and communities. With the significant differences and correlation between the outcomes of the STSTS test and standard measures, the findings suggest the use of “unable” to “able” outcomes of STSTS to indicate ambulatory individuals with SCI with different LEMS and mobility. In addition, the findings further suggest the use of ability to rise from a chair without hands to identify those with adequate LEMS (nearly 80% of the total muscle strength) and ability of walking functionally with the least support walking device. Thus, the STSTS test, particularly when assessed with arms by the sides, may be used as a simple and practical standard measure for home visits and among PHC providers to detect and monitor LEMS and mobility of ambulatory individuals with SCI in various clinical, community, and home settings.
However, the findings contain some limitations. First, the STSTS test is a simple measure with crude outcomes of “able” and “unable,” and thus the outcomes may not sensitive to detect change over time, particularly in individuals with chronic SCI. Second, the study recruited participants who could rise from a chair with or without hands independently to minimize the confounding factors due to the external assistance on the outcomes of the STSTS test. However, such criteria resulted in all participants being able to perform STSTS with arms on a walking device and limited the data analysis for the reliability and validity of this condition. Third, as a nominal outcome (pass or fail), the reliability data of the STSTS test in this study were reported using kappa coefficients that could be influenced by the prevalence index, this is, the proportion of agreements on the positive categorization (pass) differed from that of the negative outcome (fail).33 However, the low prevalence index (approximately 0.3) could confirm the strength of the kappa reported in the present study, that is, the true agreement between raters, not the chance agreement. Fourth, the participants were assessed for tactile sensation as required for the AIS protocols. A further study assessing proprioceptive sensation, which is another crucial sensation for movement control, may confirm the correlation between the outcomes of the STSTS test and the perceptual apparatus for these individuals. Moreover, a further prospective study in a larger number of participants is needed to confirm the ability of STSTS outcomes to detect falls in ambulatory individuals with SCI.
Funding Statement
Financial Support This work was supported by the funding from the Faculty of Associated Medical Sciences, and the Fundamental Fund (2023), Khon Kaen University, Khon Kaen, Thailand.
Footnotes
Conflicts of Interest
The authors declare no conflicts of interest.
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