Cut -Off Body Mass Index (BMI) For Diagnosing Malnutrition...

You are doing a new patient consultation for an 81-year-old man who has recently joined the practice. You notice that he is very thin and wonder if he may be malnourished. According to NICE, what is the cut-off body mass index (BMI) for diagnosing malnutrition?
A. < 17 kg/m􀳦
B. < 17.5 kg/m􀳦
C. < 18 kg/m􀳦
D. < 18.5 kg/m􀳦
E. < 19 kg/m􀳦

Answer: D. < 18.5 kg/m􀳦

Discussion:
Malnutrition is an important consequence of and contributor to chronic disease. It is clearly a complex and multi factorial problem that can be difficult to manage but there are a number of key points to remember for the exam.

NICE define malnutrition as the following:
 a Body Mass Index (BMI) of less than 18.5; or
 unintentional weight loss greater than 10% within the last 3-6 months; or
 a BMI of less than 20 and unintentional weight loss greater than 5% within the last 3-6 months

Around 10% of patients aged over 65 years are malnourished, the vast majority of those living independently, i.e. not in hospital or care/nursing homes. Screening for malnutrition is mostly done using MUST (Malnutrition Universal Screen Tool). The algorithm is shown below:

 it should be done on admission to care/nursing homes and hospital, or if there is concern. For example an elderly, thin patient with pressure sores
 it takes into account BMI, recent weight change and the presence of acute disease
 categorises patients into low, medium and high risk

Management of malnutrition is difficult. 
NICE recommend the following points:

 dietician support if the patient is high-risk
 a 'food-first' approach with clear instructions (e.g. 'add full-fat cream to mashed potato'), rather than just prescribing oral nutritional supplements (ONS) such as Ensure
 if ONS are used they should be taken between meals, rather than instead of meals