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Journal of Rehabilitation Research and Development
Vol. 38 No. 2, March/April 2001

Measuring the effects of seating on people with profound and multiple disabilities--a preliminary study

Aileen R. Neilson, BSc, MSc; Geoff I. Bardsley, BEng, PhD; David I. Rowley, BMedBiol, MD, FRCS; James Hogg, BA, BA, PhD; Mo Malek, BSc, MSc, MSc, PhD; Gwendolyn C. Morrison, BA, MSc, DPhil; Craig A. Kirkwood, BSc, PhD

Tayside Orthopaedic and Rehabilitation Technology Center, Ninewells Hospital, Dundee DD1 9SY, Scotland; White Top Research Unit, University of Dundee, Dundee DD1 4HN, Scotland; Department of Management, University of St. Andrews, St. Andrews, Fife, KY16 9SY, Scotland; Department of Management, University of Nottingham, University Park, Nottingham, NG7 2RD, England

This material is based upon work supported by the NHS Research and Development Programme for People with Physical and Complex Disabilities (project number PCD/A1/48).
Address all correspondence and requests for reprints to: G.I. Bardsley, Tayside Orthopaedic and Rehabilitation Technology Center, Ninewells Hospital, Dundee DD1 9SY, Scotland; email:

Abstract — This paper describes a preliminary study to investigate a range of approaches that might be used for measuring the effects of special seating on people with profound and multiple disabilities and their carers. A number of tools are proposed for measuring the effects on quality of life, function and carer satisfaction. The results of applying these tools to measure the effects of intervention with customized molded seating on nine people with multiple disabilities are described. The results suggest that these tools are sensitive to this intervention, showing a general beneficial effect with good carer satisfaction. The study points the way towards application of these tools to people with a wider range of disabilities and to different interventions.

Key words: evaluation, learning disabilities, multiple disabilities, outcomes, seating.


   This paper is somewhat unusual in its format, commencing with a general introduction, followed by the overall objectives and methodology of the study. Each proposed measurement tool is then presented separately in terms of:

   The paper finishes with a discussion and conclusion for the study as a whole.


   The objectives of special seating systems for children or adults with severe postural impairments are generally to maximize comfort and promote function, thus improving the quality-of-life of the patient and possibly of their carers. However, to date there have been relatively few published reports that point to the use of instruments to determine the efficacy of the use of adaptive or special seating devices by individuals with multiple disabilities. Furthermore, even the few studies that have attempted to adopt a broad-based approach to outcomes measurement have limitations. For example, Colbert and colleagues' (1) evaluation of the results of the provision of DESMO seats for young children with cerebral palsy ages 18 months to 8 years included the ability of the seat to produce overall relaxation, assist head control, enhance feeding, improve upper limb function, and prevent deformities. Questionnaires were completed by parents, primary therapists, and members of the fabricating team to assess overall relaxation and upper limb function, cosmesis, capacity to accommodate growth, and comfortable seating alternative. Satisfaction was reported at 80 percent, and the postural needs of patients were met in similar numbers. The authors also referred to the qualitative comments from the longer term users in their evaluation such as "the chair enabled the child to relax, and the chair improved social interaction or integration with family and friends." However, Colbert et al. did not measure these items and no baselines were established that would provide some indication to both the nature and extent of the changes observed.

   The apparent absence of suitable quality-of-life instruments in particular is increasingly being addressed. De Ruyter, for example, highlights that we have little knowledge about the suitability of such "wellness" instruments for people with disabilities, specifically consumers of assistive technology services (2). More recently, Felce recommends a need for breadth of measurement and methodological flexibility in quality-of-life measurement in patients with disability: "we do not know how to measure quality of life definitely, but we do have many measures in our collective tool-kit which address particular life domains ..... we should encourage studies which use multiple measurements" (3). Felce also argues that the most important aim of quality-of-life measurement in this field is to relate the experiences of individuals with disability to that of the wider world. Comparing quality of life data of individuals with physical and intellectual impairment with the general population norms and ranges will help establish whether the life circumstances and satisfaction in various domains are similar to the general population or have a significantly different profile.

   This study represents an exploratory attempt to address these issues to further the development of instruments useful for evaluating the consequences of the provision of special seating and wheelchairs.


   This preliminary study set out to conduct trials with a number of tools by which the effects of seating interventions may be measured with respect to changes in patients' and carers' quality of life, functional ability, and carer satisfaction. Specifically the objectives of the study were threefold:

  1. To review existing tools and determine which are most likely to be useful;
  2. To conduct trials with tools to measure the impact of intervention with molded seats;
  3. To analyze the study results to determine the relative merits and the applications of these tools.


   The study group consisted of nine adults referred to Dundee Limb Fitting Centre for customized molded seat inserts for use in wheelchairs (Table 1). Eight of the nine subjects had previously used molded seats and received replacement seats made to a new configuration. The remaining subject received a moulded seat but had not previously used one. Five were male (19, 23, 25, 25, and 34 years of age) and four were female (19, 19, 19, and 20 years of age). All subjects had severe cerebral palsy with profound learning disabilities, were unable to walk, and were totally dependent on carers for performing activities of daily living (e.g. feeding, dressing, toileting, transferring, wheelchair mobility). The entire group had extremely poor or no postural stability with significant skeletal deformities (e.g. spine, hip contractures, and pelvic obliquity). All carers were able bodied; three were parents; five were care assistants/social care officers; and one was a nurse.

Table 1.
Subject demographics.

Subject Sex Age Main carer

1 female 20 parent
2 male 23 care assistant
3 male 34 care assistant
4 female 19 care assistant
5 male 25 care assistant
6 female 19 parent
7 male 25 nurse
8 female 20 parent
9 male 19 care assistant

Seating Systems
   All subjects received plastic molded seating customized to match their individual body shape and requirements for postural support (4). Such specialized seating systems are specifically intended for severely disabled individuals with low sitting ability and skeletal abnormalities. The technique is well documented, using a bead-bag vacuum consolidation technique to determine seated shape, which is then replicated in molded plastic. The seat is then supported in an appropriate wheelchair.

   All subjects were assessed, using the measurement tools described below, pre-intervention and again at 3 to 6 months after the provision of a customized molded seat. Three other patients were assessed 6 months to 1 year postintervention. Each subject acted as his/her own control for comparison of results postintervention.

   While patient-based self-report assessments of the impact of medical treatments and procedures on quality of life are the ideal to be aimed for, this is not possible for subjects who are too intellectually impaired to respond to questions. In this study, carers reported on behalf of patients as well as on their own quality of life.

   Analysis and interpretation of the study results were limited to examining patterns and trends in the data, rather than statistical tests of significance, owing to the small sample studied.


   Golberg (5) suggests that when measuring the health effects of interventions in patients with cerebral palsy the evaluation should include an assessment of changes in clinical factors, in adaptive behaviour and function, patient satisfaction, and quality of life. This study has taken each of these broad categories of assessment and adopted measurement tools which were considered to be the most appropriate and nearest to being validated for this application, although none was found specifically tested for seating or for people with multiple disabilities.

Tool 1: The Short Form-36 Health Survey (SF-36)
SF-36: Description
   At the time of writing the SF-36 is the most widely used generic measure of health status in the UK and has been shown to have good response rates and to be reliable and valid as a health status measure in a wide variety of settings (6-8). The instrument contains 36 items over eight dimensions of quality of life, including physical and social functioning, role limitation owing to physical problems, role limitations owing to emotional problems, energy and vitality, mental health, pain, and general health perception. Item scores for each of these domains are summed and transformed using a scoring algorithm into a percentage scale, with 0 representing the worst, and 100 the best possible health status. The SF-36 was administered to carers on behalf of patients before intervention and again at 3 to 6 months and at 6 to 12 months postintervention. Comparisons were also made against normative data for the general population (8) to determine the nature of any differences between the two groups.

SF-36: Results (Table 2)
   Table 2 summarizes both the form and degree of changes in SF-36 scores for the nine subjects. The questions making up the SF-36 were well understood and completed by all carers, completion taking on average about 5 minutes. Carers did comment on the rather inappropriate content of the physical function dimension, which assumed all patients were ambulant. Table 2 shows that all patients had zero scores on the physical function dimension pre- and postintervention. However, shifts in quality of life of a mainly positive nature were recorded for the remaining seven dimensions. For the entire sample, improvements were apparent from changes in mean scores at 3-6 months on seven of the eight SF-36 dimensions. At more than 6 months postintervention, improvements in mean scores were sustained over pre-intervention scores on six dimensions but had deteriorated or returned to near baseline levels on two dimensions (general health and energy and vitality). The largest improvements appeared to occur for social function, role limitations owing to physical problems, role limitations owing to emotional problems, and pain, with smaller improvements indicated for mental health, energy and vitality and general health at 3-6 months.

Table 2.
Results of SF-36 scores.

SF-36 dimension (see ** below) SF-36 score pre-inter-
SF-36 score 3 to 6 post-inter-
Change of SF-36 score, 3 to 6 months post-inter-
vention for total of 9 subjects
SF-36 score over 6 months post-inter-
Change of SF-36 score, over 6 months post-inter-
vention for total of 6 subjects
Typical range of SF-36 score for general population in comparable age range (ref. 8)
      Number of subjects   Number of subjects  
      Increase No change Decrease   Increase No change Decrease  

PF 0 0 - - - 0 - - - 90.1 - 93.9
SF 64.2 (30.3) 86.43 (13.3) 6 2 1 66.7 (39.8) 3 1 2 85.7 - 91.3
PRL 41.7 (39.5) 83.3 (17.7) 8 0 1 66.7 (40.8) 4 0 2 86.9 - 92.0
ERL 59.3 (40.1) 85.2 (29.4) 6 1 2 77.8 (40.4) 2 3 1 78.8 - 87.1
MH 67.6 (20.5) 75.1 (22.4) 6 0 3 68.7 (23.5) 3 1 2 70.2 - 75.8
EV 56.7 (15.4) 61.7 (15.6) 5 2 2 46.7 (25.6) 2 1 3 58.3 - 66.4
P 50.6 (22.3) 71.6 (24.9) 6 1 2 68.5 (37.5) 4 1 1 81.7 - 87.5
GHP 47.2 (26.2) 56.7 (21.8) 3 1 5 40 (23) 1 0 5 72.0 - 77.3

* = cell values give arithmetic mean, with (standard deviation);
** = SF dimension code: PF = physical function, SF = social function, PRL = role limitations - physical, ERL = role limitations - emotional, MH = mental health, EV = energy and vitality, P = pain, GHP = general health perceptions.

   Comparisons with normative data suggest that before intervention, subjects have much lower scores than the general population on all dimensions, at 3-6 months scores approach levels reported for the general population and after 6 months scores are beginning to decline well below those of the general population, but not below pre-intervention scores.

SF-36: Strengths and Limitations
   The preliminary results show that the SF-36 appears to be sensitive to changes in role limitations due to physical problems, social function and pain. This finding is encouraging given these themes are commonly held goals for seating amongst patients and their carers as well as clinicians, for seating interventions.

   The main limitation of this study's investigation of the SF-36 perhaps not surprisingly related to the physical function dimension which included items such as "walking" and "climbing stairs" and was clearly inappropriate for wheelchair bound subjects totally dependent on their carers. It is not surprising then that all respondents answered "yes limited a lot" for these activities. These constructs have also been shown to be inappropriate for some older populations (9).

   One way to overcome this limitation might be to supplement the results of the SF-36 with existing measures of functional independence in activities of daily living (ADL) such as the Functional Independence Measure for adults (FIM) or the WeeFIM for children or the Barthel Index (10,11,12). These scales generally describe what the individual is capable of doing within the context of their disabilities, and assess the degree of caregiving assistance and equipment modifications needed to accomplish complex functional skills such as eating. However, these measures would be of limited use in measuring change in individuals with profound to severe impairments as subjects would continue to register on the extreme ends of these scales (i.e., totally dependent). Thus, these measures are likely to exhibit essentially the same problem as the physical function dimension of the SF-36.

   An alternative method of overcoming this limitation may be to include some additional questions involving functional activities (e.g. sitting) that are more in keeping with the lifestyle of non-ambulant patients and of fundamental importance for many patients and their carers because of its large impact on his/her overall quality of life. Adapting the physical function dimension to make it more suitable for use with non-ambulant subjects may indeed constitute a new measure specifically for this population and thus would require that any questions be tested thoroughly. However, the results of this study demonstrated that seven of the eight dimensions could continue to be administered, scored, and reported in the same way, allowing direct comparison across these dimensions with other patients groups.

   Comparison with the health status of the general population shows a much lower value for this group pre-intervention, as would be expected. Values 3 to 6 months postintervention were found to be suprisingly close to those of the general population, especially considering the severe nature of this group's disabilities. These values, however, drop when measured more than 6 months postintervention, although only 2 dropped below the preintervention values.

   Many explanations of these observations could be proposed, but the consistency of improvement immediately postintervention makes it appear reasonable to assume that the seats are providing an improvement in health status and that the SF-36 tool is sensitive to this. The subsequent deterioration is less clear and could be attributed to many different causes such as:

   Clearly, further work is required to investigate these intriguing preliminary observations.

Tool 2: Time Trade-Off (TTO)

TTO: Description

   The TTO approach is one of a series of score-scaling techniques devised by economists in an attempt to assign a single numerical value to a health state (13). The TTO values are calculated as a ratio of life expectancy in their current health state to an equivalent number of years at perfect health:


   These values are known as health state scores or utility ratings, and are a global measure of health-related quality of life with a score on a scale ranging from 0 to 1.0. Values of 0 represent an extremely poor quality of life in those individuals for whom death would be equivalent to their present state. A score of 1.0 represents a very high quality of life in those individuals whose current health would be equivalent to their perception of perfect or full health.

   For example, a 50 year old individual whose life expectancy may be a further 25 years, may state that 10 years of perfect health is equivalent to 25 years of life in his present health state (i.e., he would be willing to give up as many as 15 years of current life to achieve 10 years of perfect health.) The utility rating of his current health is:

     10 years ÷ 25 years = 0.4

Increases in TTO values reflect a net gain in health-related quality of life.

   An additional benefit of this approach is that it has been shown to be applicable to measure the well-being of family carers (14).

   In this study, the authors were concerned that despite "significant" improvements in quality of life, treatment effects may not register on a scale with pre- and postintervention anchored in normal perfect health since both the before- and after-treatment states are so severely disadvantaged compared to normal health. Therefore, an alternative evaluation method of the TTO that asked carers to compare the pre-intervention state with the postintervention state was used (see Appendix). This alternative evaluation method was considered potentially to be more sensitive to differences between two health states when respondents are considering those states relative to one another rather than being valued purely against normal health. Figures 1a, 1b, and 1c give graphical representation of this method. This rationale has already been applied to other geometric scaling techniques (15).

An illustration of visual analog scales for answers to TTO questions
Figure 1. Visual analog scales for answers to TTO questions.

   Six time tradeoff questions were administered and health state scores calculated for patients and carers before and after intervention, as shown in the Appendix.

TTO: Results (Table 4)
   The series of TTO questions put to carers pre-and postintervention took longer to administer than the SF-36 because of the complexity of the questions (on average about 15 minutes). Nevertheless, it was reassuring to note that, despite this complexity, all carers managed to interpret the questions and provide health state evaluations with respect to the patients' and their own quality of life.

Table 4.
Health status (TTO) results' analysis.

    Patient   Carer
  Health status scaling* Change of TTO scores from pre- to post-inter-
vention for total of 9 subjects
Health status scaling* Change of TTO scores from pre- to post-inter-
vention for total of 9 subjects
    Number of subjects   Number of subjects
    Increase No change Decrease   Increase No change Decrease

Usual TTO                
Pre-intervention 0.70 (0.28)   N/A   0.97 (0.07)   N/A  
Postintervention 0.75 (0.23) 5 4 0 0.97 (0.07) 1 8 0
Alternative TTO for determining pre-intervention score 0.52 (0.28) 7 2 0 0.88 (0.17) 5 4 0

* = cell values give arithmetic mean, with (standard deviation)
N/A = not applicable.

   Considering the results from the "usual" TTO approach, the seating interventions appeared to bring about some improvement in patients' quality of life but only very small improvements in carers' quality of life (Table 4). Health state scores improved for 5 patients using the usual approach and for 7 patients using the alternative approach. Health state scores improved for only 1 carer using the usual approach and for 5 carers using the alternative method. The mean health gain indicated from the usual TTO health scaling estimates are 0.05 for patients and 0 for carers. The alternative TTO scalings indicate a mean health gain of 0.23 for patients and and 0.09 for carers.

TTO: Strengths and Limitations
   The results indicate general health state gains for this group of patients following seating interventions. However further investigations are needed in order to validate this result. In particular the minimal health gain perceived by carers was unexpected and is considered worthy of further work. The alternative TTO approach appears to be more sensitive to quality of life improvements than the usual approach and is recommended for future studies. Further development of this approach should focus on a more visual description of the health states being valued as described in the Appendix and Figures 1a, 1b, and 1c and which should take less time to administer and complete. Recent work has described a new tool for measuring health state entitled the Euroquol EQ-5D (21,22) which uses visual analog scales and which may prove to be an appropriate tool.

Tool 3: Satisfaction with Seating Results
Satisfaction: Description
   Satisfaction of the carer with the seating intervention results was evaluated using the questionnaire shown in Figure 2 and completed by the carer. This was comprised primarily of a series of visual analog scales that asked carers to assess their satisfaction with the results of intervention. The themes for these questions were based upon carers' personally reported objectives prior to intervention (e.g. to enhance sitting comfort, posture and function). Carers were also asked whether they would be prepared to recommend the patient to undergo the procedure again.

A replica of the satisfaction questionnaire
Figure 2. Satisfaction questionnaire.

Satisfaction: Results (Table 5)
   The results suggest that six out of nine carers appeared to be satisfied with the overall outcome of the seating intervention and reported the overall results had met or exceeded their expectations (dimensions 1, 2, and 3 in Table 5). Common goals for seating included improvements in comfort (9), posture (6), sitting/feeding function (6), head control (4), and appearance (4). The outcomes of intervention relating to these specific aspects were perceived favorably by most carers. For example, six carers reported positive results with respect to improving comfort. A further six carers reported that improving sitting and posture was an important intervention outcome. All perceived the seating intervention had gone some way to meeting this goal. Eight of the nine carers stated that they would most definitely recommend the individual to have the treatment again given the same situation while one carer was undecided (subject 5).

Table 5.
Satisfaction with seating results.

  Visual analog scale rating (cm)
Subject: 1 2 3 4 5 6 7 8 9

Satisfaction dimensions                  
Overall outcome 7.6 6.2 7.9 1.9 5.9 0.6 7.8 3.5 8.2
Overall satisfaction 7.4 5.2 8.4 3.5 7.7 0.4 8.8 3.7 9.7
Fulfillment of expectations 5.8 5.4 6.6 5.0 1.8 0.4 7.2 1.3 9.6
Comfort 7.6 5.3 7.4 0.5 8.4 0.6 7.7 2.7 9.4
Sitting 7.7   6.0   7.0   6.7 6.0 8.3
Head control     6.2   8.6   8.2   8.7
Appearance     7.2     0.7 5.7   7.2
Posture 8.6   7.0   5.2   8.2 6.1 7.5

Ratings were determined postintervention using questionnaire in Figure 2.

Satisfaction: Strengths and Limitations
   The development of the satisfaction questionnaire reflects the aspects of intervention outcome most important to the patients' carers and was based on their comments at the time of initial assessment. Thus, for example, concerns relating to comfort, posture, appearance, and function were addressed. The questionnaire was then targetted to measure perceptions of satisfaction in terms of the effects of the intervention on these concerns.

   McComas et al. (16) developed a seating clinic satisfaction questionnaire for assessing the impact of the process as well as the product with respect to client satisfaction (16). In the study by McComas et al., process items included all events leading up to, but not beyond, the creation of the seating inserts such as communication, time, persons in the clinic, process time, responsibility, and organization. These process items may have a very significant influence on the patients' and carers' satisfaction with the outcome of an intervention. Future work on satisfaction may consider including these elements.

Tool 4: Functional Assessment: Video Recordings of Function and Behavior
Functional Assessment: Description
   Video recordings made of subjects receiving various types of seating systems are common evaluation tools for assessing function and behavior (17,18). In this study, single subject designs and videotaped analysis were used to quantify changes in sitting posture with respect to feeding behavior with carer involvement in three illustrative cases (subjects 2, 4, and 5). Video recordings were made pre- and postintervention, each with a total recording time of 15 to 30 minutes. These were edited into a number of smaller sequences of approximately 2 minutes each and randomly grouped into pairs, with each pair representing a "before and after" set to be viewed by the two observers. Random allocation within each pairing was then performed to allocate the pre- or postintervention segments to be shown first or second. This was done to minimize bias from clinicians' tendency to see improvement in the postintervention videos if they believe the intervention is a good one. Personal judgments of observed changes in function and behavior were rated using 10-cm visual analog scales (see Figure 3). Observers were also asked to provide brief comments on the visual cues that led them to reach a particular decision.

An illustration showing the visual analog scale used to score and record change in function from
Figure 3. Visual analog scale used to score and record change in function from videotapes.

Functional Assessment: Results
   The results of the video assessment of sitting position with respect to feeding behavior for subjects 2, 4, and 5 are presented in Table 6. Paired analysis of video sequences revealed that the general pattern of change was reported with some degree of consistency (i.e., deterioration, no change, or improvement). Sitting posture and feeding behavior in two subjects (4 and 5) were reported by both observers to have been very much improved postintervention while more modest improvements were reported for subject 2. Common visual cues from video recordings mentioned by observers for the basis for their judgments included: better overall body and head positions with respect to feeding; easier swallowing with less choking and "mopping" up by the carer; better eye contact with the carer and view of immediate environment and more comfort and happier when being fed by their carers.

Table 6.
Video analysis scoring of sitting posture.

  Visual analog scale rating (cm)
Subject 2 4 5

Observer 1 5.5 9.5 8.4
Observer 2 6.5 7.5 9.2

Ratings are from the postintervention perspective. Analog scales were labeled from 0 cm indicating very much deteriorated, 5 cm indicating no change, to 10 cm indicating very much improved.

Functional Assessment: Strengths and Limitations
   Video analysis of changes in function and behavior would seem to be a good observational instrument. In this study, the results and comments made by observers indicate that feeding had improved postintervention. It would also be useful to corroborate these findings with other quantifiable measures, for instance as evidenced by weight gain and decreased feeding time.

   The main limitation of using video recordings is that it would not always be feasible to employ this approach because it requires more time, resources, equipment, and people than the other approaches discussed. Carers might therefore also be asked to complete an "equipment" style questionnaire that could be used more generally as an instrument for assessing sitting posture and feeding behavior. For example, Hulme et al. (19) assessed the effects of seating on oral-motor functioning as it relates to eating and drinking in 11 children with multiple disabilities using equipment questionnaires with a behavioral base. They employed both open-ended and discrete questions of each child's motor behavior completed by parents 3 months before and 6 months after the receipt of the seating devices. Analysis of the data pointed to a significant improvement in sitting posture and head alignment during eating and drinking. The authors noted a significant increase in the frequency with which liquid and food was retained in the mouth, and in the number of children progressing from bottle to cup drinking and from eating blended to chopped to cut-up food.

   The results of the present study are inconclusive with respect to comparisons about the value judgments made by clinicians and carers, although it is well documented that carers' and clinicians' reports of the outcome of medical interventions from the patients' perspective can be very different (20). However, these preliminary findings do suggest that, predictably, some contradictory results may be evident when measuring the outcomes of seating interventions. For example, in subjects 2 and 5, therapists and carers generally reported improvement and satisfaction, respectively, with the outcome of treatment. In the case of subject 4, therapists reported improvement in function but carers were less positive about the outcome of the seating intervention. Given the complex nature of the patient's disabilities the results also point to the possibility that carer's expectations for special seating interventions may not be especially high. For example, the carer of subject 4 reported poor overall results (1.9 cm), dissatisfaction with the overall outcome (3.5 cm), and little impact on improving comfort (0.5 cm), but nevertheless reported that the overall outcome met with expectations for the seating intervention.


   In general, all the proposed outcome measurement tools appear to be potentially useful, showing sensitivity to what could be assumed to be the effects of the seating intervention. The results are not entirely consistent for all subjects, an observation that is to be expected and that has several possible explanations:

   These difficulties are inherent in studies of this nature but may be investigated in future studies through more careful selection and control of subjects and through the use of a much larger group of subjects.

   It is notable that eight of the nine subjects of this study had previously used molded seating with the effect that their improvement in quality of life is likely to have been much less than subjects who previously were using a less appropriate form of seating. This effect is worthy of further investigation and should be borne in mind in similar studies.

   The results from the SF-36 tool are particularly interesting in showing improvements in quality of life immediately postintervention, which were then followed by a subsequent decline. The reasons for this are uncertain and indicate the need again for a more detailed study with regular measurements over a longer period of time. Furthermore, the long-term effects of the use of seating and wheelchair interventions are largely unknown and should be a priority area for future study.

   This study largely adopted existing validated tools of measurement. The study highlighted areas for potential improvement in these tools; for example, in using visual analog scales for TTO estimates coupled with an alternative approach to their determination. Care is required in adopting such enhancements, as their validity is yet to be tested. Developments of new tools such as the Euroquol EQ-5D (21,22) are likely to take place continuously and may well provide the required improvements in the future.

   Depending on the nature of the study, not all these tools are likely to be needed in one study. Availability of time alone may strongly influence the choice of tool. The functional assessment was particularly time consuming to apply and complex to analyze. Clearly these tools need to be carefully selected to meet the specific objectives of each individual study. Ideally, services for the provision of interventions of this nature should include some form of outcome measurement in their routine procedures. Time is at a premium in these settings, but nevertheless services should consider including tools such as satisfaction and either the TTO or SF-36 type of measurement. The EQ-5D is particularly interesting in this context as it combines the means of generating a quality of life profile with a means to measure overall quality-of-life in the one tool. The advantages of providing quantified assessments of the benefits of any service are highly significant in the current pervasive climate of having to justify any use of resources.

   A novel feature of this study is the use of carers to answer questions on behalf of their clients. The accuracy of their answers is open to debate, as their views may be far from impartial, particularly where intra-family relationships are involved. Future studies may investigate this accuracy by asking the same questions to carer/client pairs where the client is slightly less disabled and capable of answering these questions.

   In addition, the inclusion of the carer as an individual affected by interventions on his/her client is considered important as many instances of intervention with Rehabilitation Technology may have little impact on the client but may have a major effect on the carer. Examples of this could include the provision of powered attendant-controlled wheelchairs or a powered hoists to transfer clients. Such interventions may not directly affect the client but could reduce dramatically the physical burden on the carers and improve their quality of life. Any benefit analyses of services should take this into account if a complete picture of the impact of an intervention is to be determined.

   The trend for the study to indicate that carers perceive a relatively low benefit from these interventions was considered to be surprising in view of the potential improvement in client independence. This group may, however, have such severe disabilities that despite significant functional improvement, they remain entirely dependent.

   This study has concentrated on the application of these outcome measurement tools to a very specific group of patients and the use of a particular single intervention. It seems reasonable to assume that the same tools could be applied to a much wider range of patients and interventions. Indeed, this study forms one part of a larger study encompassing interventions of surgery and orthoses, where these tools were applied successfully.


   The following are the key conclusions arising from this study:


   Invaluable contributions to the project were made by J. Colvin, D. Condie, J. Miller, L. Hunter, A. Smith, and staff of Dundee Limb Fitting Centre. Thanks are due to the patients and their carers, without whom this project would not have been possible.

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