Our literature search yielded four questionnaires for assessing LSM (see Table 1), which we discuss in more detail below.
University of Alabama Life-Space Assessment (UAB-LSA)
The UAB-LSA is by far the most common LSM assessment method . Baker and colleagues set out the original validation for the composite UAB-LSA score using longitudinal data from the prospective University of Alabama at Birmingham (UAB) Study of Aging . Their study population represented a random sample of 306 Medicare beneficiaries aged 65 or over. Test–retest reliability was 0.96 [95% Confidence Interval (CI), 0.95–0.97] when comparing composite UAB-LSA scores at initial interview to 2-week follow-up phone call.
Although the questionnaire was designed to be interviewer administered, some studies showed the questionnaire’s suitability for self-report. For example, the South Australian Omnibus postal survey  included the UAB-LSA for self-report, achieving an overall response rate of 59.5%.
The questionnaire distinguishes five life-space levels: (1) other rooms than the bedroom, (2) area outside the house, (3) neighbourhood, (4) outside neighbourhood, but in town, and (5) outside town. Each life-space level is allocated a sub-score based on a multiplication of average weekly frequency and independence of movement (based on preceding 4 weeks), and a total composite score is summated across levels, with a maximum of 120.
Mean composite scores varied by studied population. The largest prospective study of LSM to date found a mean score of 84.9 [standard deviation (SD) 24.2] . This was a cohort of 3892 relatively healthy, community dwelling men, aged 71–98 years. Other studies have reported significantly lower mean scores varying from 41.7 (SD 20.9) to 64.5 (SD 24.9) [11, 30]. Some studies used a composite UAB-LSA score < 60 to define ‘restricted LSM’ [11, 13].
The UAB-LSA has been tested in at least 13 different languages in older, community-dwelling populations across the world.
The Life-Space Questionnaire (LSQ)
The original LSQ was developed by Stalvey et al. . For the original validation study, they recruited 200 people with cataracts aged 55–85 from an outpatient eye clinic. They found LSQ scores were positively skewed. This is likely due to the relatively young cohort. In addition, the questionnaires were administered in clinic, thus likely excluded many patients unable to travel independently to the hospital.
The LSQ was designed to be interviewer administrated, but has also been used for self-completion, with response rates ranging from 67 to 85% [22, 31]. Use of LSQ in participant completed surveys appeared to be acceptable and feasible.
The questionnaire comprises nine ‘yes/no’ questions regarding a person’s movements across nine life-space zones in the preceding 3 days (questionnaire available online at: https://www.uab.edu/medicine/ophthalmology/images/research/LifeSpace.pdf). The first six zones are similar to the levels in the UAB-LSA, with level 2 (area outside the house) split into two zones: immediately outside your home, e.g. porch, and further outside your home perimeter, e.g. parking lot. The last three zones refer to (7) outside your county, (8) outside the state and (9) outside the region. The total score ranges from 0 to 9, reflecting the number of zones a person has moved in; the frequency and independence of these movements are not taken into account. Several studies have modified the original LSQ. For example, by expanding the questionnaire to include the preceding 2 months , by assessing six life-space zones in the last week , using a four-point scale for only two zones , or using a reversed scale of 0–5, with 0 implying high LSM .
For the original LSQ instrument, scores tend to be skewed towards the positive end of the scale. Some studies found a mean score of 6 (SD 1.4) in a community-dwelling older population [17, 31], whereas Satori et al. reported a mean LSQ score of 7 (SD, 1.3) . The latter studied a population of 2,737 participants who lived largely independent of formal care. Stalvey et al.  suggested to define a restricted LSM as a total score of 5 or lower. This was accepted by Byles et al. , who further suggested classifying a score of 6 as ‘mid’ and of 7–9 as ‘high’ scores.
The Nursing Home Life-Space Diameter (NHLSD) questionnaire
The NHLSD questionnaire was developed by Tinetti et al. in 1990 . It was validated in 398 residents of three nursing homes in New Haven, Connecticut . Average subject age was 82 (range 69–93), and residents who were bedbound, chair-bound or ‘restrained’ were excluded. Test–retest reliability was high (r = 0.92), as was reliability between assessors (r = 0.95). The NHSLD was designed to be nurse-administered only.
The score involves a calculation based on the frequency of residents’ movement, ranging from 0 (bedbound) to 50 (leaving the facility daily) based on four life-space thresholds: within residents’ own room (1), within the unit (2), outside the unit (3), and outside the facility (4). Scores can be multiplied by 2 to indicate complete independence of movement, resulting in a maximum score of 100. However, the majority of scores tend to be in the lower end of the 0–100 range. Tinetti et al.  found a mean NHLSD score of 27.1 (SD 10.2) among 398 residents. Bergland et al.  reported a mean score of 25.2 (SD 10.9) in 322 nursing home residents in Scandinavia who required assistance with activities of daily life. The Recourse Use and Disease Course in dementia—Nursing Home (REDICNH) study looked at 696 new NH admissions across Norway and found a median score of 36 (interquartile range 26).
When performing LSM assessments in an institutionalised environment, mobility is more likely to be influenced by external factors such as staff availability and facility routine, rather than being primarily driven by intrinsic motivation of the participant. Whilst this still conforms to the mobility construct as set out by Webber et al. , direct comparison with community-based LSM assessments should be made with caution.
Life Space at Home (LSH) assessment
The LSH assessment was designed to measure LSM for housebound older people only. It was developed and validated by Hashidate et al. , who included 20 housebound community-dwelling older people undergoing a home-care rehabilitation programme. It was designed to be administered by researchers. Since its development in 2013, deployment of the instrument in other studies has not been reported.
For the assessment, four unique life-space ‘destinations’ within the participant’s home are defined (for example, entrance, dining room, bathroom, and toilet), and a measurement of distance between each destination and the participant’s bedroom is taken. This makes the assessment relatively complex, and may limit the instrument’s use outside a research context. For each destination, a score is then calculated by multiplying this distance by 2 if performed independently, or by 1.5 if using equipment; and then again multiplied by the frequency of movements in the preceding week. The final LSH score is the summation of these four destination-specific scores. As each participant’s score is unique based on the size of their house, there is no upper limit for the total score. Hashidate et al.  reported a mean LSH score across all 20 participants of 643.2 (SD 461.1).
As with the NHLSD questionnaire, scores will be influenced by the availability of assistive services, thus LSM score will be more dependent on external factors than in regular community settings.