Stineman and colleagues studied the effect of functional recovery on survival after lower extremity amputation in a population of military veterans. This retrospective study used a published validated Physical Independence Grading System to express meaningful physical function profiles of progressive independence over time. They hypothesized that functional grades achieved by amputees would serve as predictors of mortality risk even after accounting for other risk factors. A large number of patients did not recover past the first grade of physical independence, indicating severe physical dysfunction in this cohort. Primarily, younger unmarried patients with fewer interventions achieved higher functional grades of physical activity, an intuitively reasonable conclusion. Concomitant with this observation was the finding that amputation level was not associated with mortality after adjusting for demographic data and other clinical characteristics; however, the overall age was still related to 6-month mortality. The finding that amputation level did not predict mortality is somewhat counterintuitive on the basis of what is known about limited mobility in patients who have undergone above-knee vs below-knee amputation. The authors mention that the physiologic effects associated with age and amputation level affect functional recovery and, thereby, influence mortality. This point indicates the weakness of the clinical parameters in this study and similar analyses used to predict mortality and outcome. In the absence of physiologic, proteomic, or genotypic analysis, these results must be interpreted with caution. Recent research initiatives in studies of patients who have experienced trauma have created funding opportunities (“glue” grant [http://grants.nih.gov/grants/guide/pa-files/PAR-07-412.html], National Institute of General Medical Sciences, National Institutes of Health) that match analysis of clinical parameters with proteomic and genomic analysis of patients to predict and understand the complexities of outcome and recovery. These initiatives must be extended to the patient population with vascular disease undergoing rehabilitation to obtain data that will be more predictive of mortality and functional recovery.
Watkins MT. Survival Analysis in Amputees Based on Physical Independence Grade Achievement—Invited Critique. Arch Surg. 2009;144(6):552. doi:10.1001/archsurg.144.6.552