Age, gangrene among predictive factors for amputation in diabetic foot patients

Yet, only peripheral vascular disease and infection were significant with stepwise regression analysis.

Issue: February 2008

Aziz A. Nather, FRCS, MD
Aziz A. Nather

Major amputation remains a significant complication of patients with diabetic foot problems. Now, research indicates the predictive factors for below-and above-the-knee amputation in these patients.

In a prospective study, Aziz A. Nather, FRCS, MD, and colleagues prospectively studied 202 patients with diabetic foot problems treated at the National University Hospital in Singapore between January 2005 and May 2006. A univariate analysis of the cohort showed the following significant predictive factors for limb loss from major amputation:

older than 60 years;
comorbidities such as ischemic heart disease and stroke;
Ankle Brachial Index score of less than 0.8;
glycosylated hemoglobin level (HbA1C) of more than 7%;
diabetic complications such as nephropathy, sensory neuropathy and peripheral vascular disease;
gangrene;
infection; and
pathogens such as pseudomonas aeruginosa and Methicillin-resistant Staphylococcus aureus (MRSA).

However, a stepwise logistic regression analysis revealed that only peripheral vascular disease and infection were significant.

“Clinicians need to be aware of the significant risk factors as presented in this research,” Nather told Orthopedics Today. “These factors pose a high risk that could lead to limb loss.” He presented the research at the 15th Triennial Congress of the Asia Pacific Orthopaedic Association.

Infected ulcer head.

Neuropathic ulcers on a patient’s foot.

Necrotising fasciitis of the left leg.

Images: Nather AA

Predictive factors

To determine the predictive factors for amputation, investigators noted the patients’ diabetes type and duration, presence of diabetic complications and comorbidities, categorized their type of diabetic foot problem, and assessed their ulcers using Wagner’s classification. They also took blood and tissue cultures and recorded their patients’ full blood count and HbA1C and C-reactive protein levels. Finally, they detailed whether patients received surgical or conservative treatment and noted if the patient underwent amputation.

The cohort had a mean age of 60 years and an equal distribution of men and women. The investigators found that 72.8% of the patients showed poor endocrine control and 42.1% had sensory neuropathy, according to the study abstract. Of the common diabetic foot problems found, the investigators discovered that most patients had gangrene (31.7%), infection (28.7%) and ulcers (27.7%). The study revealed that 74.8% of patients were surgically treated and 27.2% underwent major amputation, including 20.3% below-the-knee and 6.9% above-the-knee procedures.

Preventing amputation

“The mortality rate for patients who have undergone major amputations is considerably high: 10% at the time of surgery, about 30% within 1 year and 70% within 5 years,” Nather told Orthopedics Today.

“Patients must realize that major amputations lead to loss of life. Therefore, it is of utmost importance that diabetic patients monitor their diabetes and look after their feet well to prevent or delay the need for major amputations.”

For more information:
Aziz A. Nather, MD, FRCS, is an associate professor and senior consultant for the department of orthopedic surgery at the National University of Singapore. He can be reached at the National University of Singapore and National University Hospital, Singapore 119074; 65-6772-4323; e-mail: dosnathe@nus.edu.sg. He has no direct financial interest in and products or companies mentioned in this article.

Reference:
Nather AA, Chionh SB, Chan YH, et al. Epidemiology of diabetic foot problems and predictive factors for limb loss. #F084-2. Presented at the 15th Triennial Congress of the Asia Pacific Orthopaedic Association. Sept. 9-13, 2007. Seoul.