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Purpose of Review
Assess validity of measures used in adults with lower limb amputation, whether patient characteristics can predict relative effectiveness of different lower limb prosthesis (LLP) components, and long-term use of LLPs.
- 61 ambulatory and functional outcomes, and other measures, have been evaluated, of which 19 have been validated and found reliable in studies applicable to the Medicare population. However, many studies use nonvalidated measures.
- A small number of studies, only half of which used validated measures generally did not find patient or other characteristics that may predict who would most benefit from a given LLP component.
- The few studies that assessed long-term use of LLP found that between 11% and 22% of patients abandoned their LLP after 1 year; people with transfemoral (above the knee) amputations are more likely to abandon their prostheses than those with transtibial (below the knee) amputations. About 11% to 37% of people with LLP use them only indoors 1 to 7 years after they first received the prostheses.
Lower limb prosthesis (LLP) candidates are a heterogeneous group. Many LLP options exist and how to best match an amputee with a LLP is unclear. Optimal selection of devices is hampered by limited studies, as well as use of a wide range of evaluation metrics, some of which have not been validated in this population.
We addressed questions pertaining to: assessing validity, reliability, and related metrics for assessment techniques, predictor tools, and outcome measures in lower limb amputees; determining which patient and other characteristics may predict which LLP component may be best for different lower limb amputees (i.e., assessing heterogeneity of treatment effect); determining whether patient expectations align with their outcomes with LLPs; evaluating whether patients are satisfied with the process of obtaining their LLPs; and describing the long-term continued use of LLPs by those prescribed a prosthesis. We searched six databases and other sources through November 30, 2016 [to date] for eligible studies.
The search identified 19,037 unique citations. Of the 261 studies (reported in 276 articles) eligible for inclusion (171 US and 90 non-US), 136 (52 percent) were natural experiment studies, 107 (41 percent) were experimental studies (randomized or non-randomized controlled trials), and 18 (7 percent ) had other study designs that did not fall into either of the other categories.
We found 92 eligible studies that assessed performance characteristics of 61 measures (assessment techniques, prediction tools, and outcome measures). Of these, 29 have been both validated and found reliable, but only 19 are generally applicable to the Medicare population. These measures mostly assess ambulation and function in people with lower limb prostheses. Of 11 studies that provide data to allow assessment of heterogeneity of treatment effect, five used both validated predictors and outcomes, three of which assessed microprocessor knees. These studies mostly included younger men with unilateral transfemoral amputations due to trauma. Overall, studies did not identify participant characteristics that predict which lower limb amputees would most benefit from a given component (low strength of evidence), whether restricted to validated predictor and outcome measures, assessing all predictors and measures, or based on a multivariable prediction model. Two studies provide low strength evidence that people are satisfied with their encounters with their prosthetists. No eligible study addressed how study participants’ preprescription expectations of ambulation align with their functional outcomes. Based on eight eligible studies there is moderate strength of evidence that about 11 to 22 percent of lower limb amputees who receive a LLP prescription abandon the prosthesis at about 1 year and that people with unilateral transfemoral amputations are about twice as likely to abandon their LLP than those with unilateral transtibial amputations. There is low strength of evidence that 11 to 37 percent of LLP recipients use their prostheses only indoors.
Numerous measures of ambulation, function, quality of life, and other patient-centered outcomes exist for people with lower limb amputations: however, relatively few have evidence of reliability and validity in studies representative of the Medicare population. The validated measures should be used to form a core set of measures for use in future research studies of LLP. Currently, there is not evidence to support the selection of specific components for patient subgroups to maximize ambulation, function, and quality of life or to minimize abandonment or limited use. Further high quality research in representative samples of people with LLPs is needed to inform optimal matching of prosthetic components to patients and to assess patient expectations and satisfaction with care.