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Table 4 Description of the outcome measures recorded at baseline and follow-up (six months post-baseline)

From: A randomised controlled trial comparing the effectiveness of tai chi alongside usual care with usual care alone on the postural balance of community-dwelling people with dementia: protocol for the TACIT trial (TAi ChI for people with demenTia)

Item What it measures How it is measured Unit of analysis Justification
Primary outcome
Difference in score from the person with dementia between the two arms at six months post-baseline:
 Timed Up and Go (TUG) test [64] Dynamic balance Continuous measure of time (in seconds) to complete the task. A cut-off point will not be used because there is no value that can be recommended from existing evidence [48, 49]. In addition to using a stopwatch, performance on the TUG will be measured using a Balance Sensor (THETAmetrix) that contains an accelerometer to digitally record biomechanical movement, and is a small, inexpensive device that is wireless and corrects for tilt dynamically. The data on the device will be downloaded immediately after each test and stored on the researcher’s laptop / tablet and labelled using the participant’s unique ID number. The TUG is quick and simple to administer in the community [49] and has been recommended for screening for falls risk [50] and assessing gait and balance for preventing falls [51]. While no particular measure of dynamic balance has been recommended in the literature, systematic reviews have identified that the TUG has excellent reliability [42], a strong correlation with falls in retrospective studies [47], is more effective at ruling in falls (0.74 specificity) among individuals classified at high risk of falls [52], and is more suitable with older people who are relatively less healthy and have lower functioning [48]. Devices such as the balance sensor have been shown to produce reliable and valid data for the TUG and its subcomponents [53, 54].
Secondary outcomes
Difference in score between the two arms at six months post-baseline on the following:
 Person with dementia - ×2 balance tests
  Berg Balance Scale (BBS) [55] The BBS is an objective measure designed to assess functional balance and fall risk in adult populations [55]. The BBS takes an overall assessment of an individual’s balance; “underlying motor systems, static stability, dynamic stability, functional stability limits, anticipatory postural control, and sensory integration” p. 13 [56]. This is a 14 item scale with a 5-point response for each item (0–4), with the sum score used (minimum to maximum possible scores of 0–56, with 0–20 high fall risk, 21–40 medium fall risk, and 41–56 low fall risk). Total score will be analysed (potential range 0–56) and will be assumed to be interval scaled. It has been recommended in a recent consensus as one of two core outcome sets for measuring standing balance in adult populations [56]. This consensus reported that this scale would be more useful among those with limited functioning (it is prone to ceiling effects among the generally healthy population) [56]. We chose the BBS for this study based on its likely ease of use among people with dementia, existing published evidence of its suitability for use with people with dementia [36, 57], and its feasibility for use in people’s homes.
  Postural sway while standing on the floor and on a foam mat [35] Static balance under usual and challenging conditions In both instances, a continuous value will be measured as total (antero-posterior + medio-lateral) normalised path length of the acceleration sway trace of the pelvis during the task. This will be recorded using a Balance Sensor (THETAmetrix), mounted over the upper sacrum (s2 spinous process) to digitally record body sway. The unit of measurement will be in milli-g/second (mg/s). The sensor is quick to use (2mins per test) and been shown to be as reliable as laboratory forceplates [58, 59].
 Person with dementia – × 4 structured interview scales
  Iconographical Falls Efficacy Scale (Icon-FES, short form) [60] Fear of falling This is a 10-item scale of fear of falling with a 4-point response for each question (1–4). Sum score (minimum to maximum possible scores of 10–40, higher scores indicating greater fear). It will be assumed that this is interval scaled data (scale of 10–40). The Icon-FES is better at identifying people at higher risk of falls compared with the Falls Efficacy Scale-International and does not produce a floor effect [60].
  Mini-Addenbrooke’s Cognitive Examination (M-ACE) [22] Brief measure of global cognitive functioning Five items: attention (assesses orientation, scored 0–4), memory (scored 0–7), fluency (assesses language, scored 0–7), visuospatial function (scored 0–5), and memory (assesses recall, scored 0–7), with a total score of 0–30. The sum score is used, with values on an interval scale of 0–30 with higher scores indicating greater cognitive function. The M-ACE is more sensitive than the Mini Mental State Examination and is less likely to have ceiling effects, which makes it particularly useful with people with mild cognitive impairment [22].
  Statue task (Reed & Spiers: Development of a spatial judgement task for use in Alzheimer’s disease: The effect of permanency in spatial environments with age, unpublished) Brief measure of visual-spatial cognitive functioning that uses a tablet to administer the task (Reed & Spiers: Development of a spatial judgement task for use in Alzheimer’s disease: The effect of permanency in spatial environments with age, unpublished). Presents participants with a series of visual scenes. The participant is asked to look at scenes with three statues and a stool, and to answer a series of questions that assesses their ability to perceive the objects in three-dimensional space and their relationships to each other. The computer automatically records the time taken to complete the task and number of errors made. A continuous measure is used for time taken to complete (in seconds) and a discrete measure for the number of errors made (frequency count). This is a measure of specific cognitive functioning from the hippocampus, which is therefore a more sensitive measure to change than a global assessment of cognitive functioning.
  ICEpop CAPability measure for Older people (ICECAP-O) [61] Quality of life 5 item scale with a 4-point response for each (1–4) Sum score used (minimum to maximum possible scores of 5–20 with higher scores indicating greater capability). It will be assumed the measure is interval scaled. This measure is from the perspective of capability to be independent, which is associated with fall risk, general balance and mobility, and sensitive to cognitive status [62]. It is also a measure recommended in guidelines on economic evaluation of fall prevention interventions [63], with results that can be compared with other economic evaluations that used the ICECAP-O.
 Carer – ×2 balance tests
  Timed Up and Go (TUG) test [64] As above As above As above As above
  Postural sway while standing on the floor and on a foam mat [35] As above As above As above As above
 Carer – × 2 structured interview scales
  ICEpop CAPability measure for Older people (ICECAP-O) [61] As above As above As above As above
  Zarit Burden Interview (short-form) [65] Carer burden 12-item scale with a 5-point response for each (0–4) Sum score used (minimum to maximum possible scores of 0–48 with higher scores indicating greater burden). An assumption will be made that the data are interval scaled. The most commonly used tool for carer burden [66], and is shorter but just as reliable and valid as the full-length version [65, 66].