Is malnutrition associated with poor outcomes after amputation?

The prevalence of malnutrition and its related outcomes in patients who underwent lower limb amputation (LLA) remain unclear due to the lack of research using validated nutrition assessment tools, but limited evidence showed a high prevalence of amputees at risk of malnutrition, according to a Singapore study.

“Although patients with deranged biochemistry and/or anthropometry parameters appear to have worse clinical outcomes, clinicians should not interpret this as an indication for nutrition intervention,” the researchers said. “Instead, validated nutrition screening and assessment tools should be used in research and practice.”

Lead researcher Xiaomei Zheng, Department of Dietetics and Nutrition, Ng Teng Fong General Hospital, Singapore, and colleagues accessed the databases of CENTRAL, PubMed, CINAHL, and Scopus to identify eligible studies using the following keywords: amputation, malnutrition, and undernutrition.

Regardless of study design, articles were eligible if they were written in English, enrolled adult patients with LLA or foot amputation, and performed preamputation nutrition assessments.

Seven articles met the inclusion criteria. Malnutrition was assessed using biochemistry and/or anthropometry, none of which were validated nutrition screening tools. [Proc Singap Healthc 2022;doi:10.1177/20101058221094864]

However, abnormal biochemistry and/or anthropometry results showed a relationship with delayed wound healing, complications, and failed amputation compared to normal ranges. On the other hand, the association observed between abnormal biochemistry and/or anthropometry parameters and mortality was less consistent.

Of the eligible studies, only one used a validated nutrition assessment tool. Its results showed that half of the population with LLA had an increased malnutrition risk, but no association was seen.

Although the association between preoperative malnutrition and postamputation clinical outcomes remains unclear, a study by Banning and colleagues reported at least half of the patients who underwent LLA to be at risk of malnutrition. [Ann Vasc Surg 2019;64:213-220]

In addition, a study by Eneroth and colleagues found that majority of these individuals had weight loss and poor appetite, which are common components of malnutrition screening tools. [Int Orthop 1997;21:104-108]

“Validated nutrition assessment tools are important as they are required to diagnose malnutrition accurately and provide a valid association between malnutrition and clinical outcomes,” the researchers said. “Using an inappropriate nutrition assessment tool will not only lead to an erroneous association but more importantly misguide treatment.”

Most studies used unvalidated nutrition screening tools because such tools were not yet available when these analyses were conducted. Some of the eligible studies were written prior to the release of the first validated tool, Subjective Global Assessment (SGA), in 1987. [JPEN J Parenter Enteral Nutr 1987;11:8-13]

“Although it is unclear if malnutrition is associated with poor outcomes in patients with amputation, it is still important to routinely assess malnutrition risk using nutrition screening tools in all patients before amputation,” the researchers said.

“In individuals identified to be at risk of malnutrition via nutrition screening, established nutrition assessment tools should be used to accurately diagnose malnutrition so that prompt and targeted nutrition interventions can be administered,” they added.

Such action may benefit malnourished amputees, as seen in a randomized control trial that reported reduced mortality and improved clinical outcomes in patients at risk of malnutrition with individualized nutrition intervention. [Lancet 2019;393:2312-2321]