One result in this study is that paraplegia is one of the predictors of future amputation compared with tetraplegia. To our knowledge, there is no literature that supports or explains this finding. A hypothetical factor that could explain this observation is the difference in duration of survival—those with paraplegia who live longer are more likely to experience end-stage consequence of vascular diseases. Another proposed factor is that those with paraplegia are generally more active and have a higher likelihood of sustaining a traumatic cause of amputation, even though this etiology of amputation is minor.An unexpected finding in our study was that of 1055 patients with SCI, only 9.8% had a PAD diagnosis. In contrast, 41.3% of those with amputation had a PAD diagnosis. JAHVH does not screen for PAD, so this likely represents only the symptomatic cases.
Diagnosing PAD in patients with SCI is challenging as they may lack classic clinical symptoms, such as pain with ambulation and impotence, secondary to their neurologic injury. Instead, the health care practitioner must rely on physical signs, such as necrosis.22 Of note given the undetermined utility of diagnosing PAD in patients with SCI, early endovascular interventions are not typically performed. We could not find literature regarding when intervention for PAD in patients with SCI should be performed or how frequently those with SCI should be assessed for PAD. One study showed impaired ambulation prior to limb salvage procedures was associated with poor functional outcomes in terms of survival, independent living, and ambulatory status.23 This could help explain why endovascular procedures are done relatively infrequently in this population. With the lack of studies regarding PAD in the SCI population, outcomes analysis of these patients, including the rate of initial interventions, re-intervention for re-amputation (possibly at a higher level), or vascular inflow procedures, are needed.
It would be beneficial for future studies to examine whether inflammatory markers, such as C-reactive protein (CRP), were more elevated in patients with SCI who underwent amputation compared with those who did not. Chronic underlying inflammation has been shown to be a risk factor for PAD. One study showed that, independently of other risk factors, elevated CRP levels roughly tripled the risk of developing PAD.24 This study suggested that there is an increased risk of dysvascular amputation among the SCI population at this center. This information is significant because it can help influence JAHVH clinical practice for veterans with SCI and vascular diseases.
Limitations
As a single-center study carried out at an SCI specialized center of a VA hospital, this study's finding may not be generalizable. Incomplete documentation in the health record may have led to underreporting of amputations and other information. The practice of the vascular surgeons at JAHVH may not represent the approach of vascular surgeons nationwide. Another limitation of this study is that the duration of SCI was not considered when looking at health risk factors associated with amputation in the SCI population (ie, total cholesterol, hemoglobin A1c, etc). Finally, the medication regimens were not reviewed to determine whether they meet the standard of care in relation to eventual diagnosis of PAD.
A prospective study comparing the prevalence of amputation between veterans with SCI vs veterans without SCI could better investigate the difference in amputation risks. This study only compared our veterans with SCI in reference to the general population. Veterans are more likely to be smokers than the general population, contributing to PAD.17 In addition, data regarding patients’ functional status in regard to transferring and ambulation before and after amputation were not collected, which would have contributed to an understanding of how amputation affects functional status in this population.
Conclusions
There is an increased prevalence of amputation among veterans with SCI compared with that of the nationwide population and a plurality were TFAs. This data suggest that those with a motor complete SCI are more likely to undergo a more proximal amputation. This is likely secondary to a lower likelihood of ambulation with more neurologically complete injuries along with a greater chance of healing with a more proximal amputation. It is challenging to correlate any variables specific to SCI (ie, immobility, time since injury, level of injury, etc) with an increased risk of amputation as the known comorbidities associated with PAD are highly prevalent in this population. Having PAD, low HDL-C (< 40 mg/dL), and paraplegia instead of tetraplegia were independent predictors of amputation.
Health care professionals need to be aware of the high prevalence of amputation in the SCI population. Comorbidities should be aggressively treated as PAD, in addition to being associated with amputation, has been linked with increased mortality.25 Studies using a larger population and multiple centers are needed to confirm such a concerning finding.
Acknowledgments
This material is based on work supported (or supported in part) with resources and the use of facilities at the James A. Haley Veterans’ Hospital (JAHVH). Authors gratefully acknowledge the inputs and support of Dr. James Brooks, MD, RPVI, assistant professor of surgery, University of South Florida (USF), and attending surgeon, vascular surgery service, medical director of the peripheral vascular laboratory, JAHVH; and Dr. Kevin White, MD, assistant professor, USF, and Chief of Spinal Cord Injury Center, JAHVH.