The perspective of the user of a prosthesis or orthosis is generally acknowledged to be an important part of defining the function of the devices they use. Even with optimal biomechanical action, the user could have very strong negative reaction due to other matters of importance to them. Because of this, practitioners and researchers will ask questions of users to elicit such information, but these are rarely developed in a formal way. While still providing important insight for the researcher or clinician, such informal questioning must be analyzed with great care because it has an unknown degree of content validity (does it measure what we think it measures?) and stability (would it measure the same under similar circumstances but at a different time, or with a different subject?). These limitations are particularly significant when we wish to compare the results of different studies.
Use of previously validated questionnaires is one way to gather the users’ perceptions in a way that allows such comparisons to be made. It is not practical for anyone interested in functional outcomes in prosthetics and orthotics to develop and validate a questionnaire. It requires rigorous development and statistical testing. In the case of the Prosthesis Evaluation Questionnaire (PEQ), the team at Prosthetics Research Study in Seattle undertook the challenge to create a general outcomes measurement tool specific to lower limb prosthesis use. The PEQ has been shown to have a high degree of content validity and temporal stability. The statistical validation of the PEQ has been described previously.1,2 As noted above, this effort was not trivial. Development of the PEQ took about 4 years, participation of a large number of subjects with amputations, full-time staff dedicated to the project, the time of many researchers and clinicians, and hundreds of thousands of dollars in project costs.
The original goal has been accomplished. The PEQ is a relatively simple-to-use instrument that can be used to answer a wide variety of questions pertaining to the functional outcomes of lower limb prostheses. Questions specific to upper limb prosthesis use are not included, though some relevant sections may be used. It continues to be used by many research groups and clinicians.
A key rationale behind the development of the PEQ was a desire for an instrument that would be sensitive to changes specific to prosthesis function. For example, a prosthesis that was quieter may have been very significant to the user, but this important effect probably would not be detected by any of the existing rehabilitation outcomes measurement instruments such as the SF-36 Short Form Physical Function, Functional Independence Measure (FIM), Sickness Impact Profile (SIP), Barthel Index for Activities of Daily Living (ADL), Frenchay Activities Index for Instrumental Activities of Daily Living (IADL), Functional Status Questionnaire (FSQ), Nottingham Health Profile (NHP), Duke Older Americans Resources and Services Multidimensional Functional Assessment Questionnaire (Duke OMFAQ) or Quality of Well Being Scale (QWB). Smith et al.3 used the SF-36 with 20 unilateral transtibial amputees.3 The subjects scored similarly to age-matched control subjects except in the areas of physical function, pain, and role limitations due to physical health problems. The results indicated that amputees differ from nonamputees but did not provide information that specifically identified limitations caused by their prostheses.
To aid in creation of the PEQ, prosthesis users participated in focus group meetings and online solicitations to determine what issues are important to users. These specific items were delineated, combined into groups of related questions and refined in an iterative process. Following this user-centered approach, the PEQ was designed as a self-report visual analog scale (VAS) style questionnaire. The respondent is free to answer each question on a continuum that relates to his or her perception of how ultimately good or poor prosthetic function may be.
The 54 questions of the PEQ are organized into nine functional domain scales, each reflecting a major area of concern for persons with amputations, such as “utility” and “appearance.” Each domain scale can be used and scored independent of the others. This provides considerable flexibility for the investigator or clinician to focus the content of the questionnaire to the topic(s) of interest. In turn, this minimizes the burden on the subject and reduces data analysis to only the most relevant questions. The domains and the issues addressed by each scale are listed in Table 1.
The PEQ also contains items that are not included in the nine computed scales. These questions are scored individually. The topics concern satisfaction, pain, transfers, prosthetic care, self-efficacy, and importance to the user of particular issues.4
USE OF THE PEQ
The PEQ is being used in a broad range of prosthetics research studies and clinical evaluations.5–18 Some specific uses of the PEQ have been: general status of prosthetic patient cohorts,6,9,11,13,14,16,17 elastomeric prosthetic liners,8 feet,7 microprocessor-controlled knees,12–18 and shock-absorbing pylons.5 Several translations of the PEQ have been undertaken, including French, German, Spanish, Japanese, Chinese, and Khmer. Tables 2–10 summarize the reported findings of several studies using the PEQ to measure prosthesis-related outcomes.
The PEQ is one of only a few detailed instruments for measuring prosthesis-related quality of life and functional outcomes. It has been validated for content and temporal stability in a group of lower limb amputees. The PEQ has been used in many different settings, from hospital clinics to biomechanical research studies. The findings have been reported to be useful and have shown significant differences with changes in prostheses tested. Several translations of the validated questionnaire are being used but have not been individually revalidated in their new translations.
The PEQ and instructions for its use are freely available from Prosthetics Research Study in Seattle for anyone who is interested in using it (http://www.prs-research.org/htmPages/PEQ.html). Any of the domain scales may be used independently and the PEQ scales may be asked in conjunction with specific questions posed to address the problem at hand. This makes for flexible focused use.
It must be stressed that “validated measures” do not replace good experimental design or relevant questioning. The PEQ can be a useful tool in measuring outcomes, but as with any tool, it must be used appropriately.
1. Legro MW, Reiber GE, Smith DG, et al. A Prosthesis Evaluation Questionnaire (PEQ). Association for Health Services Research 14th Annual Meeting, Chicago IL, June 15-17, 1997.
2. Legro MW, Reiber GD, Smith DG, et al. Prosthesis evaluation questionnaire for persons with lower limb amputations: assessing prosthesis-related quality of life. Arch Phys Med Rehabil
3. Smith DG, Horn P, Malchow D, et al. Prosthetic history, prosthetic charges, and functional outcome of the isolated, traumatic below-knee amputee. J Trauma Injury Infect Crit Care
4. Laing L, Coleman K, Boone D, Smith DG. What is important for prosthesis satisfaction. The 10th World Congress of the International Society for Prosthetics and Orthotics, Glasgow, Scotland, July 2–8, 2001.
5. Berge J, Klute G, Czerniecki J. Mobility and comfort for unilateral transtibial amputees using a shock-absorbing pylon, Journal of Proceedings, Annual Meeting and Scientific Symposium of the American Academy of Orthotists and Prosthetists, New Orleans, LA, 2004.
6. Boone DA, Ip M, Chan Y, Ho M. Baseline for evidence based practice in prosthetics service. Proceedings of the 11th World Congress of the International Society for Prosthetics & Orthotics, Hong Kong, China, Aug 1–6, 2004, p. 166.
7. Coleman KL, Boone DA, Smith DG, et al. Functional outcome assessment using objective measures of patient satisfaction and gait activity: A comparison of 2 feet. In: Soede, M, Verbout AJ, Swart M, eds. IXth World Congress of the International Society for Prosthetics and Orthotics, Amsterdam, The Netherlands, June 28–July 3, 1998, p. 690–692.
8. Coleman KL, Boone DA, Laing LS, et al. Quantification of prosthetic outcomes: elastomeric gel liner with locking pin suspension versus polyethylene foam liner with neoprene sleeve suspension.. J Rehabil Res Dev
9. Dillingham TR, Pezzin LE, MacKenzie EJ, Burgess AR. Use and satisfaction with prosthetic devices among persons with trauma-related amputations: a long-term outcome study. Am J Phys Med Rehabil
10. Engsberg JR, Sprouse SW, Uhrich ML, et al. Preliminary investigation comparing rectified and unrectified sockets for transtibial amputees. J Prosthet Orthot
11. Harness N, Pinzur M. Health related quality of life in patients with dysvascular transtibial amputation. Clin Orth Rel Res
12. Kaufman KR, Padgett D, Brey RH, et al. Objective comparison of the OttoBock C-Leg to the Mauch SNS. Proceedings of the 11th World Congress of the International Society for Prosthetics & Orthotics, Hong Kong, China, Aug 1–6, 2004 p. 157.
13. Legro MW, Reiber GE, Czerniecki JM, Sangeorzan BJ. Recreational activities of lower-limb amputees with prostheses. J Rehabil Res Devel
14. Miller WC, Deathe AB, Speechley M. Lower extremity prosthetic mobility: a comparison of 3 self-report scales. Arch Phys Med Rehabil
15. Tobimatsu Y, Iwaya T, Tamura T. Prosthesis-related QOL of the people with amputation in Japan. Proceedings of the 11th World Congress of the International Society for Prosthetics & Orthotics, Hong Kong, China, August 1–6, 2004, p. 167.
16. Trantowski-Farrell R, Pinzur MS. A preliminary comparison of function and outcome in patients with diabetic dysvascular disease. J Prosthet Orthot
17. Smith DG, Ehde DM, Legro MW, et al. Phantom limb, residual limb, and back pain after lower extremity amputations. Clin Orthop Rel Res April
18. Smith DG, Willingham LL, Allyn KJ, et al. Functional evaluation of the transition from a non-microprocessor controlled prosthesis to a microprocessor controlled prosthesis for transfemoral amputees: Early results of a clinical trial. Proceedings of the 11th World Congress of the International Society for Prosthetics & Orthotics, Hong Kong, China, Aug 1–6, 2004, p. 155.