We read with great interest the article by Hoffstad et al. (1) that addressed the important topic of mortality risk following lower-extremity amputation in people with diabetes. At a time when amputation rates and outcomes are of increasing significance in guiding care, there are few data to underpin which outcomes should be reported following amputation and which are most relevant to patients. This also includes perhaps one of the simplest measures—mortality.
Hoffstad et al. sought to determine the variations in mortality rates after lower-extremity amputation. Although some of the variation is explained, the authors concluded that “there remains a large amount of unexplained variation” (1). We think that a key element missing from this area of research—one that may help to elucidate answers to much of the unexplained variation—is agreement on key population factors and, subsequently, consistent reporting of these. The article by Hoffstad et al. highlights a number of reasons why we need to be cautious in our conclusions until we have this agreement.
The authors chose what might be considered as nontraditional exclusion criteria, removing “any individual who died within the first 2 weeks of the procedure” on the basis that their mortality is more likely “due to preexisting sepsis or due to the surgical event itself” (1). Most previous studies reporting mortality after amputation have not limited the inclusion in this way, which hinders comparison of the current findings with existing literature. A discussion of inclusion parameters related to time frame is certainly needed within the field.
Another parameter impacting mortality is the level of amputation. The final prediction model of Hoffstad et al. (1) concerns all amputations (i.e., minor and major), but mortality risk after minor amputation is much lower compared with that after major amputation (2). Prediction models might be better focused on people who have experienced major amputations only, rather than foot or partial foot amputations.
Time frames and level of amputation are two critical parameters, but others, such as first-ever or subsequent amputation, emergency or planned procedure, and comorbidities, need agreement and consistent reporting as well to better understand mortality after lower-extremity amputation. A coordinated process to determine agreement on key factors to be reported in future studies, similar to that which other conditions have benefited from through initiatives such as the Core Outcome Measures in Effectiveness Trials (COMET [3]), is recommended.
Given the rising number of people with diabetes and foot problems and the ongoing discussions putting lower-extremity amputations and their outcomes under scrutiny (4,5), further insight into the most relevant outcomes and causes of these outcomes is desperately required. We commend Hoffstad et al. (1) for attempting to tackle this issue, particularly for suggesting new approaches to estimate the effect of amputation as a surrogate marker for factors such as cardiovascular disease or renal failure. However, until agreement on key factors to be included in any study on lower-extremity amputations is reached and reported appropriately, we must be cautious in drawing strong clinical conclusions from the findings presented.
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Duality of Interest. No potential conflicts of interest relevant to this article were reported.
