Time-related changes in quality of life in persons with lower limb amputation or spinal cord injury: protocol for a systematic review

Sustaining a lower limb amputation (LLA) or spinal cord injury (SCI) is a significant event, with permanent implications for the individual’s future life. The outcomes of both LLA and SCI are highly individualised and heterogeneous, in part due to variability in the level of injury/amputation and, at least for SCI, the degree of injury completeness. The reasons for injury occurrence can also be important, with many LLA cases being related to significant existing chronic disease and related comorbidities. However, both conditions present a series of shared outcomes that have a significant impact on aspects of quality of life (QoL) [1]. For example, mobility restriction and differences in appearance lead to shared challenges around social engagement, perceived isolation and dependency, which can limit community participation [2‐7] and increase risk of depression [8‐11]. Similarly, a general loss of skeletal muscle mass and restriction of physical activity contribute to long-term health consequences associated with early ageing [12, 13] such as increased risk of cardiovascular and metabolic diseases [14‐16].

Notwithstanding, several studies have demonstrated that for individuals with a chronic motor disability the level of physical impairment does not directly correlate with patient-reported quality of life [17‐20]. QoL scales consider the resultant limitations and consequences of a disability and assess how these change over time, even when the underlying injury remains. As such, QoL measures are increasingly being recognised as an important tool for monitoring long-term outcomes following rehabilitation [21‐24]. Used in combination with assessment of functional performance, they assist in the recording of changing perceptions and patient adjustment, as well as their acceptance of life post-injury [25, 26].

Researchers in both LLA and SCI communities acknowledge the value of QoL measures as longitudinal assessment tools [17, 27‐31]. They provide a quantitative mechanism for capturing changes in post-injury health and broad level treatment outcomes, both for an individual and for a disability group, relative to population normative data. However, there is a lack of homogenous outcome data for both communities and a lack of consensus around QoL scale selection.

In part, this is due to the multifaceted nature of QoL as a construct. There are varying definitions and tools available, built around both conceptual understandings of what constitutes a person’s quality of life and design considerations specifying what facets a tool is designed to assess and for which populations. One widely utilised distinction is that between ‘objective’ and ‘subjective’ assessment measures, previously described by Dijkers and Fuhrer [25, 26]. Several LLA and SCI reviews have followed this construct and divided existing QoL measures under these headings [27‐29, 32]. Within this distinction, objective measures consider external definitions of QoL (i.e. those that are societally or culturally defined), whereas subjective measures focus on an individual’s perceptual assessment of their life relative to their expectations.

These distinctions are particularly important to consider when QoL tools have been deployed longitudinally, or when trying to capture within-population differences in response to rehabilitation or treatment. Both components of QoL should be reflected when attempting to create more personalised rehabilitation or recovery pathways for specific patient sub-groups. For example, there are ongoing shifts in the population demographics for both SCI and LLA [33‐35]. For SCI, age at onset is subject to considerable variation globally, with increasingly ageing populations in more economically developed countries (MEDC) highlighted as a potential future public health challenge [36]. Similarly for LLA, there is significant variation between countries for age at onset, aetiology and incidence [37, 38]. This variation encompasses a complex landscape, with regional public health provision intersecting with clinical advances.

Regardless, within both conditions, mean and upper age at onset and potentially life expectancy is increasing for both populations, in particular within MEDCs [34, 35, 39‐41]. Furthermore, it has been noted that a bimodal distribution may be forming for both conditions, [35, 42] with traumatic injuries relating to misadventure or conflict continuing to occur at younger ages, while the proportion whose injury results from age- or lifestyle-related factors, such as vascular disease for LLA or frailty-related falls for SCI, increases.

This potentially growing divide in age at time of injury occurrence raises questions around identifying rehabilitation or treatment requirements for different age groups [43, 44]. It also has implications when considering functional and QoL outcomes across the life course and when selecting QoL instruments [45‐47].

Previous research has been undertaken comparing SCI and LLA population QoL outcomes to population norms and healthy controls [27], but no cross-population comparisons have been reported. This leads to important questions regarding how the comparative success of long-term rehabilitation and recovery pathways can be evaluated and optimised to sustain QoL. By directly comparing the QoL scores at an individual health domain level (e.g. Physical Health, Psychological, Social Relationship and Environment for WHOQOL-BREF), we may gain insight into the condition-specific challenges of living with these disabilities.

There is a significant challenge in assessing long-term quality of life changes relative to age, due in part to a lack of longitudinal data in both SCI and LLA populations, particularly for those who suffered an injury in later life [19, 34, 48, 49]. As population demographics change and post-operative life expectancy rates can be expected to improve, the detail of variation in QoL relative to time since injury and age at onset holds increasing importance [33, 45]. There is currently a lack of consensus around the relationship between QoL with age at time of injury and time since injury, both for persons with SCI [48] and those with LLA [50, 51].

This review intends to provide a synthesis of these previously unassessed variables, alongside aetiology characteristics, to address this issue. This is required as the emergence of increasingly divided points of disability incidence may necessitate changes in care provision or categorisation.

This protocol follows the principles of The Cochrane Handbook for Systematic Reviews, and the final report will conform to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses [52, 53]. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA-P) process will be followed, as presented in Additional file 1.

This protocol was registered with the PROSPERO International Prospective Register of Systematic Reviews database (registration number CRD42018096633).

This systematic review and meta-analysis is designed to assess the independent and combined effects of age at time of injury and elapsed time since injury on quality of life in persons with chronic SCI and LLA.

By taking a cross-population perspective, this review will highlight potential discrepancies in QoL outcome for each group across the various sub-domains of the two QoL scales. This may also allow further comparative analysis between the SF-36 and WHOQOL BREF scales for use in disabled populations. Given the heterogeneity of aetiology for both conditions, a comparative view of rehabilitative outcomes is necessary to identify any global failings or successes of rehabilitative practice for the different conditions.