Discussion

A previous study at this institution evaluating mortality after major lower limb amputation for critical ischemia between 2005 and 2007 reported a 15.6% mortality rate within one month, with 5.6% occurring within the first week [11]. The findings of the present study indicate that there has been no significant change in perioperative mortality over these two decades of evaluation. For instance, mortality rates were reported at 44% in 2005 and 47.5% in 2019, demonstrating a lack of reduction between these two periods [12].

This persistently high mortality rate highlights the clinical severity of the condition and the complexity of its management. A secondary consideration is the deterioration in the quality of life for both patients and their caregivers, who frequently require specialized postoperative support [13,14]. Given these high mortality rates, quality of life must be integrated as a primary criterion in the decision-making process regarding limb revascularization versus amputation.

The primary causes of mortality in individuals in their sixth decade are typically cardiac and neurological events associated with atherosclerosis. However, these were not the leading causes of perioperative mortality in the present study. Instead, a significant number of deaths were related to factors that could potentially be mitigated through improved infection control and earlier surgical intervention before progression to systemic sepsis [15]. Furthermore, rehospitalization due to infection of the amputation stump was a frequent outcome observed during the study period, occurring in some cases despite the administration of prophylactic antibiotic therapy [16].

Over the years, several studies have been conducted to identify the primary factors leading to infection and sepsis, which subsequently increase mortality. Hospital de Base is a tertiary facility that receives patients from numerous smaller municipalities, serving a regional population of approximately 1.7 million people. However, vascular surgeons are not always available in these smaller towns to assess peripheral circulation; consequently, management is often limited to antibiotic therapy. Our findings indicate that approximately 33% of these cases involve severe ischemia requiring revascularization. Patients treated solely with antibiotics frequently experience clinical deterioration and are referred to the tertiary center at an advanced stage of their disease. Furthermore, between 85% and 90% of these patients with ulcers are diabetic, and infections involving Gram-negative bacteria are common, resulting in a mortality rate exceeding 20% [17,18].

Our data revealed that approximately 60% of patients with initially negative radiographic findings had positive cultures. This discrepancy led to the implementation of repeat foot radiography approximately 15 days post-amputation to reassess for osteomyelitis [18]. It is important to note that while plain radiography is not the gold standard for detecting pedal osteomyelitis, its universal availability in all municipalities makes it a viable tool. Adopting a strategy of repeat imaging 15 days after the initial assessment can achieve a diagnostic accuracy exceeding 90%.

Regarding the assessment of arterial circulation, performing an arterial and venous color Doppler ultrasound of the affected limb is the standard institutional protocol and is always considered for patients with peripheral artery disease. However, because this 15-year registry focuses on major amputations performed in an emergency setting, a massive proportion of these patients presented with acute, rapidly progressive infections, gas gangrene, or advanced sepsis. In these critical, life-threatening scenarios, immediate surgical intervention via emergency amputation to control the infectious focus was the absolute clinical priority to prevent mortality, rendering preoperative vascular mapping with color Doppler secondary or logistically unfeasible for the entire cohort.

Another concerning finding is the trend toward a reduction in the mean age at death among these patients. Paradoxically, we are also increasingly identifying octogenarian and nonagenarian patients with chronic arterial disease who require revascularization or amputation [19]. Palliative care is recommended not only during the active phase of dying but throughout the disease trajectory, particularly as one-year mortality rates can reach approximately 50%. This figure is comparable to, or even exceeds, the mortality rates associated with many forms of cancer [17].

One study identified significant differences in mortality rates between diabetic foot treatment centers, likely attributable to the specialized care provided for diabetic foot ulcers. Such variations in care may be a critical factor in the differing rates of major lower limb amputations [18]. A similar trend was observed at our institution, suggesting an urgent need for improved prevention and earlier intervention in regional towns, particularly regarding chronic arterial disease associated with diabetes. Recent evidence indicates that patients who undergo revascularization attempts before major lower limb amputation have a lower probability of mortality at one and three years postoperatively, underscoring the importance of early intervention [19]. In the present study, however, the majority of patients presented at advanced stages when they were no longer candidates for limb-salvage revascularization, except in cases where the procedure was performed to optimize perfusion for a specific amputation level. Another aspect observed was the fragility of these patients, which can contribute to amputations and mortality.

Cox regression analysis demonstrated that the presence of Gram-negative bacteria; male sex; the mean Wound, Ischemia, and Foot Infection score; diabetes mellitus; and end-stage renal disease were independent risk factors positively associated with amputation [20]. Therefore, infection represents a critical complication that significantly impacts mortality rates and increases the likelihood of subsequent amputations.

The overall mortality rates following major amputation were reported as 47.9%, 61.3%, 70.6%, and 62.2% at one, two, three, and five years of follow-up, respectively [21]. Another study identified a 30-day mortality rate of 22% and a one-year rate of 44%. Notably, patients with renal disease faced a 77% mortality rate at five years, representing a 3.5-fold higher risk of death [22]. Early postoperative mortality rates vary between 4% and 22% for minor and major amputations; however, data regarding the influence of patient-related factors, such as age and comorbidities, remain limited [23]. A comprehensive literature review found that 30-day mortality rates following lower limb amputation ranged from 7.1% to 51.4%, with a mean rate of 16.45% across the analyzed studies [24]. Furthermore, it has been reported that prior revascularization of the amputated limb was absent in 26% of cases, with 30-day and one-year mortality rates reaching 14% and 34%, respectively [25].

Another important aspect is wound management and dressing protocols, which can influence major amputation rates but have not been shown to impact mortality. Hyperbaric oxygen therapy was administered to approximately 300 patients. While this intervention reduces the rate of major amputation, it does not significantly affect mortality [26]. Consequently, the development of regional guidelines and specialized training regarding appropriate dressing techniques is fundamental [27,28].

Study limitations

This study had a few limitations. There was a lack of detailed stratification and the inability to perform statistical adjustments or sensitivity analyses for certain crucial clinical variables. Notably, the exact staging of chronic kidney disease, which is a major public health problem affecting approximately 11.5% of adults and is strongly associated with mortality [29], as well as specific microbial profiles and infection severity, were not uniformly or systematically recorded across the 1,744 patients in this 15-year historical registry. Furthermore, recent literature emphasizes that post-amputation mortality is particularly elevated in older females and patients with chronic kidney disease, reinforcing the urgent need for comprehensive risk assessment and optimized perioperative management [30]. Consequently, a formal multivariable adjustment or quantitative staging analysis for chronic kidney disease was mathematically unfeasible in the current study and would introduce severe statistical bias. However, these specific clinical, demographic, and metabolic factors are currently being evaluated individually and prospectively in ongoing research by our group.