Responsiveness and minimal clinically important difference of the five times sit-to-stand test in ambulatory individuals with spinal cord injury: A six-month prospective cohort study

Abstract

Objectives

To explore the responsiveness and minimal clinically important differences of the five times sit-to-stand test in ambulatory individuals with spinal cord injury.

Methods

This six-month prospective cohort study was conducted in 109 individuals with spinal cord injury who could walk with or without a walking device for at least 10 meters. Participants were assessed for the five times sit-to-stand test in the four arm-placement conditions and standard measures to determine responsiveness of the test, at baseline, and one, three, and six months. At six months, participants were also interviewed for the global rating of change to estimate the minimal clinically important differences of the five times sit-to-stand test.

Results

The five times sit-to-stand test showed large internal responsiveness (standardized response means>0.83), with moderate external responsiveness as compared to the 10-meter walk test (ρ = −0.28 to −0.48, p < 0.005). The changes in the outcomes >2.27 and >2 s could be used to indicate a level of minimal clinically important change for participants who executed the test with and without hands, respectively.

Conclusion

The five times sit-to-stand test is a responsiveness measure for ambulatory individuals with spinal cord injury. The levels of minimal clinically important differences found in this study (>2.27 and >2 s) can be applied as a useful benchmark for the decision of clinically relevant changes over time for these individuals.

Keywords

Research tool rehabilitation neurology muscle strength walking mobility

Introduction

The five times sit-to-stand test is a common measure with the outcomes reflecting walking and balance ability, as well as functional lower limb motor strength for many individuals.^1–3 Recently, the test has been assessed for its validity and reliability, and subsequently applied in ambulatory individuals with spinal cord injury using various arm placements according to the individuals’ abilities, including arms on a walking device, arms on knees, arms free by sides, and arms crossed over the chest.^4–6 However, the decision for clinical and research application as well as clinical relevant changes of the test still need other psychometric properties, especially for the responsiveness and minimal clinically important difference. These data are important for the decision-making process of the treatment modification, evaluation for clinical significance of an intervention, and determination for appropriate sample sizes of intervention studies for particular individuals.^7–10

Previously, the responsiveness and minimal clinically important difference of the five times sit-to-stand test have been reported for other individuals.^{11, 12} With bilateral sensorimotor impairments and intact brain functions,¹² the present researchers believe that the test would have specific data for clinical application among ambulatory individuals with spinal cord injury. Thus, this study investigated the responsiveness and optimal minimal clinically important difference of the five times sit-to-stand test when assessed with different arm-placement conditions (i.e. arms on a walking device, arms on knees, arms free by sides, and arms folded over the chest) in these individuals. The researchers hypothesized that the five times sit-to-stand test is a responsive tool with specific minimal clinically important difference for clinical application in ambulatory individuals with spinal cord injury. However, these data would be affected by arm placements while performing the test.

Methods

Participants

This six-month prospective cohort study was conducted in ambulatory individuals with sub-acute and chronic spinal cord injury from rehabilitation centers and communities. The inclusion criteria were age at least 18 years old, and body mass index between 18.5 and 29.9 kg/m² to minimize confounding factors due to various body sizes on the outcomes of the study.¹³ In addition, the eligible participants had motor-incomplete lesions due to traumatic or non-progressive causes as determined using criteria from the International Standards for Neurological Classification of Spinal Cord Injury,¹² and the ability of standing up from a chair independently with or without hands, and walking with or without a walking device over at least 10 meters. The exclusion criteria were any signs and symptoms that might affect the individuals’ ability to involve in this study, such as musculoskeletal pain with an intensity of pain more than 5 out of 10 on a numeric pain-rating scale, joint deformities, and other neurological disorders. The sample size was estimated using data from a previous report¹⁴ with set the sensitivity of the five times sit-to-stand test at 0.6 and allowance for the error at 0.1, with the consideration of 20% drop-out. The data indicated that this study required at least 105 participants.¹⁵ All participants gave a written informed consent form that was approved by the Institutional Ethics Committee for Human Research (HE601349) prior to participation in the study.

Research protocols

The eligible participants were interviewed and assessed for their demographics, and spinal cord injury characteristics. Then they were assessed for the baseline outcomes of the study, including the five times sit-to-stand test in four arm-placement conditions (Figure 1), and standard measures, including the 10-meter walk test and the walking index for spinal cord injury II. Then the participants were prospectively assessed for these measures over the three time frames; including at one, three, and six months thereafter to verify responsiveness of the five times sit-to-stand test. The responsiveness is the ability of the test to detect the accurate change as it is actually occurred over time, which is divided into internal responsiveness, that is, the ability of the tool to detect change over a specific time frame, and external responsiveness, that is, the extent to which the change in the test over a specific timeframe is associated with changes in the standard measures.^{7, 8} In this study, we applied standard measures relating to walking ability because the outcomes of the five times sit-to-stand outcomes relating to components necessary for independent walking, that is, a high priority for ambulatory individuals with spinal cord injury who undergo rehabilitation.^{16, 17}

Upon data completion at six months, participants were also interviewed using a global rating of change questionnaire^18–20 that was used as another anchor for the analysis of minimal clinically important difference of the five times sit-to-stand test based on participants’ judgment in addition to the objective 10-meter walk test. The minimal clinically important difference or clinical significance reflects the least change in the outcomes that both health professionals and researchers agree on which changes in functions are clinically relevant.⁹

All measurements were executed by the same experienced health professional and excellent reliability rater (LK). Participants were provided a period of sufficient rest between the trials and the tests. They were involved in normal daily activities and routine treatments as needed during participation in this study. Details of the measurements are outlined below.

Five times sit-to-stand test: It is an excellent reliability measure (intraclass correlation coefficient >0.950) with the outcomes significantly correlated with sensorimotor scores, lower limb functions, mobility, and walking ability (ρ = −0.39 to −0.72, p < 0.01).^{1–3, 6} Participants were seated on a standard armless chair with their back upright against the backrest of the chair, hip flexion at 90°, and feet placing flat on the floor with the heels at 10 cm behind their knees. The tests recorded the time required to complete five chair-rise cycles at the fastest and safe manner while placing their arms in four conditions: (1) arms on a standard walker, (2) arms on the knees, (3) arms free by their sides, (4) arms folded over the chest, in a random order according to their own ability without compulsory to complete all tests if they were unable to do so.^{1, 4–6} The average time required from the command “go” to the participant's back touching the backrest of the chair on the fifth repetition over the three trials was reported.^{5, 6}

10-Meter walk test: Outcomes of the test are reliable (intraclass correlation coefficient = 0.974 to 1.000)^{6, 21} and valid for people with spinal cord injury as compared to lower extremity motor strength, balance and endurance with responsive to indicate improvement in walking capacity during six months after rehabilitation.^{20, 21} Participants walked at their preferred speed along a 10-meter walkway with or without a walking device according to their ability, and the time used during the middle four meters was recorded to minimize acceleration and deceleration effects.^{6, 14} The average data over the three trials was converted to a walking speed.⁵ The changes of walking speed over each follow-up period were used to analyze the responsiveness. The changes of walking speed over six months >0.13 m/s are regarded as a clinical relevant change of the 10-meter walk test in ambulatory individuals with spinal cord injury.²² Participants who demonstrated such changes, either increase or decrease, were used to assign into the “change” group; if not, they were categorized into the “no change” group for the analysis of minimal clinically important difference of the five times sit-to-stand test.

Walking index for spinal cord injury II: It is excellently reliable (100% of agreement) and valid to reflect independence in individuals with spinal cord injury (ρ = 0.97).²³ The test was recorded while participants completed the 10-meter walk test with the outcomes dividing into 21 levels, from 0 (unable to walk) to 20 (can walk without braces and/or devices and without physical assistance for at least 10 m).²⁴ The changes of walking index for spinal cord injury II over each time point were additionally applied to indicate responsiveness of the five times sit-to-stand test relating to physical assistance, lower extremity bracing, and ambulatory aides needed during walking.^{23, 24}

Global rating of change questionnaire: This questionnaire is highly valid (r = 0.72 to 0.90) for self-rated importance of change, with acceptable agreement (87%) and accuracy in classifying improved versus non-improved based on participants’ perception.²⁵ The global rating of change questionnaire asked the participants to assess their current health status at sixth month as compared to their baseline condition. The magnitude of changes was divided into a 15-point scale from −7 to 7, whereby −7 indicated a very great deal worse, 0 inferred about the same or no change, and 7 reflected a very great deal better. The findings were used to categorize the participants into the “change” group (±5 to ± 7 points) or “no change” group (0 to ± 4 points) for estimating the minimal clinically important difference of the five times sit-to-stand test.²⁶

Data analysis

Descriptive statistics were applied to explain demographics of the participants and findings of the study. Then the internal responsiveness (i.e. the ability of the five times sit-to-stand test to detect the actual change over a specific time frame) was determined using standardized response means,⁸ which were calculated by dividing the mean differences of the five times sit-to-stand outcomes between the two assessment points by the standard deviation of these differences.²⁷ The standardized response means of 0.20, 0.50, and >0.80 indicated small, medium, and large responsiveness, respectively.^{28, 29} External responsiveness, that is, the extent to which the change in the five times sit-to-stand outcomes over a specific timeframe is associated with changes in the standard measures,⁸ that is, the 10-meter walk test and walking index for spinal cord injury II, was determined using the Pearson's correlation coefficients (r) or the Spearman's rank correlation coefficients (r_s) for normal and non-normal data distribution, respectively.¹⁵ The strength of the correlation (r or r_s) ≥0.3 (moderate correlation) indicated external responsiveness of the tool.³⁰ The minimal clinically important difference or clinical significance was estimated via an anchor-based method using the objective 10-meter walk test and subjective global rating of change measures. Then the receiver operating characteristic curves were used to estimate the optimal cut-off scores to discriminate the “change” and “no change” participants.¹⁶ The area under the receiver characteristic curve of ≥0.50 is considered as an acceptable minimal clinically important difference of the tool to detect meaningful clinical relevant change.¹⁰

Results

One hundred and nine participants completed this six-month prospective study. Most participants were at a chronic stage (86%, an average post-injury time of 76.3 ± 72.1 months), had mild lesion severity (AIS D, 85%), and walked with a walking device (63%, Table 1). All participants could complete the five times sit-to-stand test with the arms on a walking device, whereas about two-thirds of them (n = 72 to 74 [66% to 68%], Table 1) could execute the test with the other arm-placement conditions, and more than half of these participants (54% to 56%) walked without a walking device (Table 1). At baseline, there were no significant differences in the five times sit-to-stand outcomes among the conditions (14.4 to 14.9 s, p = 0.923). Inversely, the data of the 10-meter walk test and the walking index for spinal cord injury II of participants who could complete the five times sit-to-stand test with their arms on a walking device were significantly poorer than those who could execute the test of the other three conditions (p < 0.001, Table 1). After six months, some participants showed the changes in their mobility (12 to 24 participants for each condition), in which nine to 11 participants decreased mobility and all of them did not involve in any routine training programs.

Table 1.

Demographics and spinal cord injury characteristics of the participants who could complete each condition of the five times sit-to-stand test.

Variable		Arms on a walking device (n = 109)	Arms on knees (n = 74)	Arms by sides (n = 73)	Arms folded over the chest (n = 72)
Age (years)^a		55.8 (13.1) [53.3 to 58.3]	55.3 (11.6) [52.7 to 58.0]	55.3 (11.6) [52.5 to 57.9]	55.1 (11.7) [52.4 to 57.9]
Body mass index (kg/m²)^a		23.2 (3.8) [22.4 to 23.9]	23.5 (3.8) [22.6 to 24.3]	23.4 (3.8) [22.5 to 24.3]	23.4 (3.8) [22.5 to 24.3]
Post-injury time (months)^a		76.3 (72.1) [62.6 to 90.0]	78.4 (72.7) [61.5 to 95.3]	78.9 (73.1) [61.9 to 96.0]	79.8 (73.3) [62.5 to 97.0]
Gender: male^b,c		87 (80)	63 (85)	62 (85)	61 (85)
Stage of injury: chronic^b,c		94 (86)	63 (85)	62 (85)	61 (85)
Cause of injury: non-traumatic^b,c		54 (50)	35 (47)	34 (47)	33 (46)
Level of injury: incomplete paraplegia^b,c		67 (61)	32 (53)	38 (52)	37 (51)
AIS: D^b,c		93 (85)	71 (96)	70 (96)	69 (96)
Using a walking device^b:	Walker	40 (37)	14 (19)	14 (19)	13 (18)
Using a walking device^b:	Crutches	9 (8)	3 (4)	3 (4)	3 (4)
	Cane	20 (18)	17 (23)	16 (22)	16 (22)
	None	40 (37)	40 (54)	40 (55)	40 (56)
Five times sit-to-stand test (seconds)		14.9 (7.9) [13.4 to 16.4]	14.7 (11.6) [13.6 to 15.8]	14.7 (5.2) [13.5 to 15.9]	14.4 (4.6) [13.3 to 15.4]
10-meter walk test (meters/second)		0.54 (0.31) [0.48 to 0.60]	0.66 (0.29) [0.59 to 0.73]	0.66 (0.29) [0.59 to 0.73]	0.67 (0.29) [0.60 to 0.74]
Walking index for spinal cord injury II (20 scores)		16.8 (3.4) [16.1 to 17.4]	18.2 (2.9) [17.5 to 18.8]	18.2 (2.9) [17.5 to 18.8]	18.2 (2.9) [17.6 to 18.9]
Global rating of change at 6^th month (7 scores)		2.51 (2.37) [2.06 to 2.96]	2.26 (2.25) [1.73 to 2.78]	2.29 (2.26) [1.76 to 2.81]	2.25 (2.25) [1.72 to 2.77]

AIS: American Spinal Injury Association Impairment Scale.

Data are presented using mean (standard deviation) [95% confidence interval].

Data are presented using n (%).

These variables were categorized according to the following criteria: Gender: male/ female; Cause: non-traumatic/ traumatic; Level of injury: incomplete paraplegia/ incomplete tetraplegia; Stage of injury: sub-acute (≤12 months)/ chronic (>12 months); AIS class: C/D.

Responsiveness

The standardized response means of the five times sit-to-stand test, for all arm-placement conditions at all follow-up periods, were high (0.83 to 1.22, Table 2), indicating large internal responsiveness of the test, similar to that of the 10-meter walk test (standardized response means = 0.84 to 1.15). On the contrary, the standardized response means of the walking index for spinal cord injury II were low for every follow-up period (standardized response means = 0.16 to 0.27, Table 2), suggesting small internal responsiveness. The five times sit-to-stand test also showed external responsiveness as the changes in the outcomes, for all arm-placement conditions, were significantly correlated to the changes of the 10-meter walk test outcomes in every follow-up period (r_s = −0.28 to −0.48, p < 0.005). However, the changes of the five times sit-to-stand test were significantly correlated to the changes of the walking index for spinal cord injury II only in the conditions with arms on the knees (during one to three months, and three to six months), arms free by their sides (during one to three months, and three to six months), and arms folded over the chest (during three to six months) (r_s = −0.27 to −0.39, p < 0.05, Table 3).

Table 2.

Internal responsiveness of the five times sit-to-stand test (FTSST) for the four arm-placement conditions.

FTSST conditions	Periods of assessments (month)	FTSST (seconds)			Standard measures
		FTSST (seconds)			10MWT (m/s)			WISCI II (scores)
		$\bar{D}$	SD( $\bar{D}$ )	SRM^a	$\bar{D}$	SD( $\bar{D}$ )	SRM^a	$\bar{D}$	SD( $\bar{D}$ )	SRM^a
Arms on walking device (n = 109)	0 to 1^st	2.24	2.45	0.91	0.073	0.075	0.97	0.25	0.93	0.27
Arms on walking device (n = 109)	1^st to 3^rd	1.25	1.21	1.03	0.059	0.067	0.84	0.18	0.85	0.21
	3^rd to 6^th	1.48	1.49	0.99	0.068	0.066	1.03	0.30	1.10	0.27
Arms on knees (n = 74)	0 to 1^st	2.30	2.03	1.13	0.091	0.079	1.15	0.25	0.98	0.25
Arms on knees (n = 74)	1^st to 3^rd	1.27	1.50	0.85	0.069	0.074	0.93	0.23	0.97	0.23
	3^rd to 6^th	1.56	1.39	1.12	0.077	0.071	1.08	0.12	0.74	0.16
Arms by sides (n = 73)	0 to 1^st	2.31	2.22	1.04	0.089	0.078	1.14	0.23	0.98	0.23
Arms by sides (n = 73)	1^st to 3^rd	1.28	1.28	1.00	0.066	0.070	0.94	0.22	0.98	0.22
	3^rd to 6^th	1.40	1.15	1.22	0.075	0.070	1.07	0.12	0.74	0.16
Arms folded over the chest (n = 72)	0 to 1^st	2.26	2.37	0.95	0.088	0.078	1.13	0.23	0.98	0.23
Arms folded over the chest (n = 72)	1^st to 3^rd	1.28	1.55	0.83	0.061	0.061	1.00	0.14	0.69	0.20
	3^rd to 6^th	1.39	1.27	1.09	0.076	0.069	1.14	0.14	0.75	0.19

$\bar{D}$ : mean of the FTSST between 2 assessment points; SD( $\bar{D}$ ): standard deviation of the mean differences of the FTSST; SRM: standardized response means; 10MWT: 10-meter walk test; WISCI II: walking index for spinal cord injury II.

Values indicate: 0.20, small; 0.50, medium; >0.80 large responsiveness.

Table 3.

External responsiveness of the five times sit-to-stand test (FTSST) for the four arm-placement conditions and standard measures.

FTSST conditions	Periods of assessments (month)	Standard measures
		10MWT		WISCI II
		r_s	p-value	r_s	p-value
Arms on walking device (n = 109)	0 to 1^st	−0.28	0.003*	−0.14	0.153
Arms on walking device (n = 109)	1^st to 3^rd	−0.38	<0.001*	−0.06	0.501
	3^rd to 6^th	−0.46	<0.001*	−0.09	0.324
Arms on knees (n = 74)	0 to 1^st	−0.34	0.002*	−0.10	0.405
Arms on knees (n = 74)	1^st to 3^rd	−0.48	<0.001*	−0.42	<0.001*
	3^rd to 6^th	−0.41	<0.001*	−0.27	0.020*
Arms by sides	0 to 1^st	−0.38	<0.001*	−0.13	0.268
(n = 73)	1^st to 3^rd	−0.46	<0.001*	−0.39	<0.001*
	3^rd to 6^th	−0.39	<0.001*	−0.32	0.005*
Arms folded over the chest (n = 72)	0 to 1^st	−0.38	<0.001*	−0.11	0.349
Arms folded over the chest (n = 72)	1^st to 3^rd	−0.42	<0.001*	−0.13	0.254
	3^rd to 6^th	−0.39	<0.001*	−0.27	0.020*

10MWT: 10-meter walk test; WISCI II: walking index for spinal cord injury II.

The data are presented using Spearman’s rho coefficient (r_s).

*Significant correlation (p < 0.05).

Minimal clinically important differences

The minimal clinically important difference of the five times sit-to-stand test, as determined using the 10-meter walk test and global rating of change questionnaire as anchor-base, showed slight differences among the conditions. The change in the five times sit-to-stand outcomes of >2.27s for the condition with arms on a walking device, and >2 s for the other three conditions showed moderate to good ability to indicate the clinically important change of the participants (area under the receiver characteristic curve = 0.60 to 0.70, Table 4). Comparing among the arm-placement conditions, the five times sit-to-stand test with arms free by sides had the best capability to indicate clinically relevant changes of the participants (area under the receiver characteristic curve = 0.70, Table 4).

Table 4.

Minimal clinically important difference (MCID) of the five times sit-to-stand test (FTSST) for four arm-placement conditions and associated data.

FTSST conditions	No change^a (n): Change^b (n)	MCID (s)	Sen. (%)	Spec. (%)	AUC (95%CI)
Using the 10-meter walk test as an anchor
Arms on walking device (n = 109)	85:24	≥ 2.27	70.8	62.4	0.69 (0.55 to 0.80)
Arms on knees (n = 74)	55:19	≥ 2.00	73.6	53.7	0.69 (0.56 to 0.83)
Arms by sides (n = 73)	55:18	≥ 2.00	83.3	56.3	0.70 (0.56 to 0.83)
Arms folded over the chest (n = 72)	55:17	≥ 2.00	82.3	53.5	0.66 (0.53 to 0.79)
Using the global rating of change as an anchor
Arms on walking device (n = 109)	85:24	≥ 2.27	58.3	58.8	0.62 (0.49 to 0.75)
Arms on knees (n = 74)	61:13	≥ 2.00	61.5	48.3	0.60 (0.44 to 0.77)
Arms by sides (n = 73)	60:13	≥ 2.00	69.2	50.0	0.61 (0.45 to 0.77)
Arms folded over the chest (n = 72)	60:12	≥ 2.00	69.2	48.3	0.60 (0.43 to 0.77)

GRC: global rating of change; 10MWT: 10-meter walk test; s: second; Sen.: sensitivity; Spec.: specificity; AUC: area under the curve.

Participants with the change of GRC 0 to ± 4 scores or 10MWT < 0.13 m/s over six-month follow-up.

Participants with the change of GRC ± 5 to ± 7 scores or 10MWT ≥ 0.13 m/s over six-month follow-up.

Discussion

Being a time-based measure affords sensitivity of the five times sit-to-stand test to detect changes in the participants, similar to the 10-meter walk test, although most participants were at a chronic stage (86%). Therefore, the standardized response means for every condition were high in all follow-up periods (>0.83, Table 2), indicating large internal responsiveness of these tests. Outcomes of the five times sit-to-stand test reflect lower limb motor strength, dynamic balance ability, and mobility that are necessary for independent walking.^{1, 5, 6} Thus, the changes in the five times sit-to-stand test over time were significantly correlated to the 10-meter walk test, suggesting external responsiveness of the tool. The large responsiveness of the standard measure, 10-meter walk test, was coherent with previous reports in ambulatory individuals with spinal cord injury (effect size = 0.92).^{20, 22} Therefore, the present findings confirmed the responsiveness of the 10-meter walk test and the five times sit-to-stand test, particularly for individuals with spinal cord injury.

Nonetheless, the small internal responsiveness of the walking index for spinal cord injury II, another standard measure, reflected characteristics of the tool that quantified external device and assistance needed in daily walking using ordinal scales.^{20, 23, 24} Such scores require dramatic change to alter the scores, which is difficult in individuals with long post-injury time and rather good walking ability (average walking index for spinal cord injury II = 16.8) in this study.^{31, 32} Therefore, the walking index for spinal cord injury II showed small internal responsiveness over time, and the external responsiveness of the five times sit-to-stand test as verified using this test was confirmed only in the conditions that relied mostly on lower limb functions (Table 3).

Meretta et al.¹⁰ also found moderate internal responsiveness of the five times sit-to-stand test (standardized response means = 0.58) and moderate correlation of the change data as compared to gait and balance measures (r_s = −0.46 to 0.43, p < 0.01) in adults undergoing vestibular rehabilitation. However, Jones et al.¹¹ found small responsiveness of the test (Cohen's effect sizes = 0.32) and very low correlation of the change scores as compared to the exercise capacity (r = −0.13, p < 0.05) in people with chronic obstructive pulmonary disease. These differences may reflect the influence of study design, standard measures, and participants’ characteristics. Jones et al.¹¹ explored the responsiveness of the five times sit-to-stand test using an experimental design, and applied exercise capacity as standard measures that may not much relate to the five times sit-to-stand tests. Inversely, this study prospectively explored the data over six months using standard gait measures. We believed that the findings would confirm responsiveness of the five times sit-to-stand test and the need for specific data in individuals with spinal cord injury.

The findings further indicated the minimal clinically important difference of the five times sit-to-stand test (Table 4) when using an objective 10-meter walk test with changes in outcomes of >0.13 m/s,²² and subjective judgment—global rating of change—with changes of >5 scores¹⁹—as anchors to dichotomize the participants into the “change” or “no change” groups. The slight differences in the minimal clinically important difference among the conditions may reflect the influence of the upper limb contribution in the test. The condition with arms on a walking device allowed upper limbs to compensate for the lower limb and balance deficits, thus the participants could complete the test within the same duration as that of the other conditions (14.4 to 14.9 s, p = 0.923, Table 1). However, outcomes of such test may need a larger level of change to indicate the improvement in the standard measures. As a result, the minimal clinically important difference of the test with arms on a walking device was slightly higher than that of the other conditions (>2.27 s, Table 4). By contrast, the other three conditions relied mostly on lower limb functions and balance ability over a small base of support.⁶ Thus, a change of >2 s could clinically reflect a change in the standard measures, especially for the condition with arms by sides. With the area under the receiver characteristic curve of ≥0.60, the findings provided acceptable minimal clinically important difference of the tool to detect change of the participants.⁹ The findings were coherent with a previous study that found the changes in the five times sit-to-stand test of ≥ 2.3 s as a clinical relevant change in participants with vestibular dysfunctions.¹⁰

The present study provided thorough evidence relating to the responsiveness and minimal clinically important difference of the five times sit-to-stand test in a large number of participants (n = 109). The findings suggested the test with arms on a walking device using minimal clinically important difference ≥ 2.27 s for those who are unable to rise from a chair without hands. Outcomes of such test can reflect walking speed, but not the need of external devices. However, for those who could stand up independently without hands, the study suggests performing the test with arms by sides and minimal clinically important difference ≥ 2 s in order for the outcomes to reflect walking as well as external devices needed. These data can be applied as useful benchmarks for clinicians or researchers to interpret the clinical relevant changes and to make agreement for the change specifically for these people.

However, there are some limitations of the study. This study limited body mass index of the participants to minimize confounding factors due to bodyweight and stature on the outcomes of the five times sit-to-stand test.¹³ In addition, the study analyzed the data according to their ability rather than levels of injury because individuals with high levels of injury would need better trunk and lower limb control to achieve the same ability as those with low levels of injury.³³ Furthermore, most participants were at a chronic stage (86%, Table 1), thus they demonstrated small changes over time. Therefore, a further study may be additionally conducted in ambulatory individuals with spinal cord injury who have various stages and levels of injury with wide range of body mass index, and data analysis separately for each subgroup to provide thorough evidence to support the responsiveness and minimal clinically important difference of the five times sit-to-stand test specifically for these individuals.

Clinical messages

The five times sit-to-stand test can be used to detect actual change over time for ambulatory individuals with spinal cord injury.

The changes in the outcomes of ≥ 2.27 s could indicate clinical relevant change of the individuals who perform the test with hands.

The changes in the outcomes of ≥ 2 s could suggest meaningful change of the individuals who execute the test without hands.

The five times sit-to-stand test in ambulatory individuals with spinal cord injury should be assessed with arms by sides.

Footnotes

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This research was supported by the Research and Graduate Studies, Khon Kaen University (RP64016), Khon Kaen, Thailand.

ORCID iD

Sugalya Amatachaya

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