The 'MUST' Report - Executive Summary
This report examines the need to screen for malnutrition in clinical practice, sets out the criteria that need to be fulfilled, and describes the development and use of the ‘Malnutrition Universal Screening Tool’ ( ‘MUST’ ) for adults, which takes these criteria into account. The tool primarily aims to identify risk of poor protein-energy status, rather than status of individual nutrients. It is linked to a care plan, which can vary according to healthcare setting, local policies, and resources. Guidance on undertaking measurements using ‘MUST’ is provided.
Section A: Screening for malnutrition: a multidisciplinary responsibility
1. Malnutrition (undernutrition) and overweight/obesity as major clinical and public health problems in the UK
1.1 Malnutrition (undernutrition): Underweight (BMI <20 kg/m2) is typically present in 10-40% of patients admitted to hospital, but malnutrition risk, established using the ‘MUST’ , is even greater. In the general population, it is estimated that one in seven subjects aged 65 years and over has a medium or high risk of malnutrition, but the prevalence is higher in subjects who are institutionalised than those who are free living (i.e. living in their own homes). Malnutrition predisposes to disease, delays recovery from illness, and adversely affects body function, well-being and clinical outcome. There is no formal economic evaluation of disease-related malnutrition but it is estimated that the cost is greater than that of obesity.
1.2 Obesity: The incidence of obesity (body mass index (BMI) >30 kg/m2) is increasing in both adults and children, and currently affects one in five adults. It predisposes to many health problems, including heart disease, diabetes, high blood pressure and osteoarthritis, with an estimated annual cost to the economy of over £2 billion, of which £0.5 billion represents a direct cost to the National Health Service.
2. Malnutrition (undernutrition): under-recognised and undertreated
Malnutrition is often unrecognised and untreated in hospitals (both in-patients and out-patients), nursing homes and in the community, causing concern among a wide range of health professionals, national organisations and colleges, UK government departments, and the Council of Europe. Despite this, there are no national guidelines for commissioners and planners of healthcare.
3. Inadequate nutritional care
Nutritional care is frequently inadequate because of diffuseness of responsibility, lack of an integrated infrastructure for dealing with nutritional problems within and between different healthcare settings, poor education, and lack of consistent criteria to identify and treat malnutrition. There are well over 50 published nutrition screening tools and many more unpublished tools in clinical use, taking anything from two minutes to over thirthy minutes to complete. These differ in the criteria they use, the weighting factors applied to the criteria, the scoring systems, the intended users (who are sometimes not specified), and the tools practical acceptability in routine clinical practice. Many have not been tested for reliability or validity, and many lack an evidence base. Furthermore, several different tools may be in use in the same hospital and in the community, contributing to confusion about how to recognise and manage malnutrition.
4. Common principles of nutritional screening and care
The problems and principles of nutritional screening are illustrated by examining the common threads that apply to underweight and overweight children and adults, including pregnant and lactating women. The section on children is also included because nutritional problems in children become nutritional problems in adults, especially if there is inadequate continuity of care. 5. Nutritional screening and assessment Nutritional screening, which is the focus of this report, refers to a rapid, general, often initial evaluation undertaken by nurses, medical or other staff, to detect significant risk of malnutrition and to implement a clear plan of action, such as simple dietary measures or referral for expert advice. Nutritional assessment is a more detailed, more specific, and more in-depth evaluation of nutritional status by an expert, so that specific dietary plans can be implemented, often for more complicated nutritional problems. This difference is often misunderstood, contributing to confusion.
6.1 Routine use of a nutritional screening tool: A nutritional screening tool should be used routinely for patients admitted to hospitals and care homes. It should also be used with new patients attending general practitioner (GP) surgeries, in those aged 75 years and over undertaking routine annual health assessments, in vulnerable groups, and in those for whom there is clinical concern (e.g. those who are frail and elderly, the poor and socially isolated, and those with severe diseases and disabilities). Screening should be repeated at intervals depending on the healthcare setting and clinical condition. The same tool should be used to screen patients at risk of malnutrition as they move from one healthcare setting to another.
6.2 Characteristics of the nutrition screening tool: (i) The screening tool should be: practical (easy to understand, easy and quick to complete, and acceptable to patients/subjects and healthcare workers), reliable, valid and evidence based. It should also incorporate a scoring system that is applicable and relevant to different clinical conditions and care settings, and be linked to a care plan. (ii) The screening tool should address the following: current weight status (e.g. underweight or obesity using BMI), as well as recent past and likely future change in weight, both of which are related to food intake and disease severity. Objective measures should be used whenever possible, and less objective measures when necessary. (iii) The screening tool should aid rather than replace clinical judgment.
6.3 The nutritional screening programme: After application of the screening test, which aims to identify patients at risk of malnutrition, it is often necessary to undertake more detailed and more specific assessment (e.g. by referral to a dietitian or nutritional support team) as part of a care plan. The policy for the entire screening programme - from the initial test to assessment, treatment, monitoring, documentation, communication and evaluation - should be established by a multidisciplinary group of healthcare workers, according to recommended procedures for screening and guideline development, and according to local resources.
6.4 Weighing scales and stadiometers: Accurate and reliable weighing scales and stadiometers, for measuring weight and height respectively, should be available to all hospital wards, outpatient clinics, care homes, GP surgeries, and other healthcare settings.
6.5 Consistent framework and principles for nutritional screening programmes: Screening programmes for malnutrition in children and obesity in adults and children should follow the same principles as screening for malnutrition in adults. Unintentional weight loss in obese individuals should be taken seriously since it may suggest the presence of an underlying disease. In contrast, persistent weight gain in children may be inadequate to sustain normal growth. Adult malnutrition screening programmes should note obesity when it exists, link with childhood nutritional programmes, and cater for individuals in different healthcare settings using the same sound principles and procedures operating through an appropriate infrastructure. Screening tests and programmes should be evaluated with respect to their application and effectiveness.
6.6 Infrastructure and clinical governance: Commissioners, planners and providers of healthcare should be part of a coherent and integrated infrastructure, extending through all levels of the health and care service from Government departments, regional and local services, to individual health and care workers. This continuum should foster the development of nutrition strategies and the establishment of responsibilities and policies for the prevention and treatment of malnutrition across conditions and healthcare settings. The effectiveness of such policies, including nutritional screening programmes, education, training and personal development plans, should be monitored and evaluated.
Section B: Validity, reliability and practicality of using the ‘Malnutrition Universal Screening Tool‘ (‘MUST’)
7. The acronym ‘MUST’
Although it is recognised that the ‘Malnutrition Universal Screening Tool’ for adults may not effectively screen for deficiencies or toxicities of certain micronutrients, it can be readily applied to all types of patient groups in different healthcare settings. These include those with eating disorders, mental health problems and critical illness, as well as those with fluid disturbances, pregnancy, or lactation. It uses the same conceptual framework for all adults, employing more subjective criteria (e.g. when there are fluid disturbances) or modified criteria (e.g. weight changes during pregnancy) in some circumstances. The acronym, which is presented in inverted commas to indicate these caveats, is also used as a means of encouraging screening for malnutrition in a range of care settings where this is currently not carried out routinely.
8. Development of the evidence base
‘MUST’ was developed for use in adults in response to the criteria set out in section A of this report. It provides a theoretical and practical framework for the clinical detection and management of nutritionally responsive conditions, caused by physical and psychosocial problems. The tool is simple, valid, and reliable, and is suitable for practical use by a range of healthcare workers operating in different healthcare settings.
9. The tool and its components
‘MUST’ was developed by a multi-disciplinary group of health professionals and patients to detect both undernutrition (poor protein-energy status, referred to as malnutrition in this document) and obesity in adults of different ages and diagnoses in different healthcare settings. The tool involves assessment of weight status (BMI), The ‘MUST’ Report 4 change in weight, and the presence of an acute disease resulting in no dietary intake for more than 5 days (or likely to result in no dietary intake for more than 5 days). It can also be viewed as tracing the clinical journey of the patient, from the past (history of unintentional weight change) to the present (current weight status or BMI) and into the future (likely effect of underlying condition). All three components can independently influence clinical outcome. In situations where weight and height cannot be measured, self-reported measurements, other surrogate measurements, and clinical judgment can be used to reliably estimate underweight, obesity and overall malnutrition risk. The tool categorises subjects into low, medium, or high risk of malnutrition and identifies the obese. It provides guidance on the interpretation of measurements, and suggests appropriate care plans, which can be modified to take into account local policy and resources.
The tool has face validity, content validity, concurrent validity with a range of other screening tools, and predictive validity. In hospitals (medical, elderly and orthopaedic wards), ‘MUST’ predicts length of stay (e.g. up to 2-4 times longer in high than low risk patients in elderly medical wards), discharge destination (e.g. to nursing homes and other hospitals from orthopaedic wards), and mortality after controlling for age. In the community, ‘MUST’ predicts rates of hospital admissions and GP visits, and shows that appropriate nutritional intervention improves outcome.
11. Reliability and internal consistency
The tool is internally consistent and reliable. It has very good to excellent reproducibility when different observers assess the same patients in hospitals (in-patients and out-patients), GP surgeries, and care homes (kappa values between 0.8 and 1.0).
The tool has been found to be easy and quick to use and acceptable to both patients/subjects and healthcare workers.
13. Further evidence based consideration
Justification is provided for the use of an acute disease effect in ‘MUST’ , equal weightings of the three component categories of ‘MUST’ (BMI, weight loss and acute disease effect), and the lower boundary BMI of 20kg/m2 for the elderly.
Section C: Guidance on undertaking measurements and using ‘MUST’
Procedures for measuring weight, height, and establishing BMI and weight loss are described, together with methods for estimating them (from ulna length, knee height, demispan, mid-upper arm circumference (MUAC)) when they cannot be measured directly.
15. Interpretation and use of the tool
Guidance is provided on how to use the tool in a range of situations, particularly those in which confounding factors influence the interpretation of weight change and BMI. Considerations and alternative measures relevant to these situations are The ‘MUST’ Report 5 Executive summary summarised below.
15.1 Fluid disturbances: (i) BMI A low BMI is more significant if underweight is present with than without oedema. In the presence of barely detectable oedema, a correction can be applied by subtracting 2-3 kg from the measured weight. MUAC can also be used as an indicator of underweight when there is oedema or excess fluid in the legs or trunk (including ascites) but not in the arms. Alternative strategies are to re-measure weight after correcting disturbances in hydration status, and to classify subjects as thin, acceptable weight, or overweight by inspecting them, noting if they are obviously wasted (very thin) or very overweight (obese). (ii) Weight change When there are large and fluctuating fluid shifts, a history of changes in appetite and presence of conditions likely to lead to weight change can be used as part of an overall subjective evaluation of malnutrition risk, which categorises patients into low or medium/high risk categories.
15.2 Lactation: (i) BMI Use measured BMI. (ii) Weight change As for oedema.
15.3 Pregnancy: (i) Pre-pregnancy BMI Measurements of weight and height before pregnancy (or during early pregnancy, which is associated with little change in body weight) or recalled values can be used to estimate pre-pregnancy BMI; MUAC changes little during pregnancy and can be used to establish approximate pre-pregnancy BMI categories. (ii) Weight change Weight gains <1kg (<0.5kg in the obese) or >3kg per month during the 2nd and 3rd trimester generally require further evaluation.
15.4. Critical illness: Acute disease effect (no or unlikely dietary intake for >5 days) Most patients in typical intensive care units are at risk of malnutrition.
15.5 Plaster casts: Synthetic and Plaster of Paris casts for upper limbs weigh <1kg; those for the lower leg and back weigh 0.9 - 4.5kg depending on the material and site (see section C.3.2.6).
15.6 Amputations: Weight adjustments can be made from knowledge of the weight of missing limb segments: upper limb 4.9% of body weight (upper arm 2.7%; forearm 1.6%; hand 0.6%); lower limb 15.6% (thigh 9.7%; lower leg 4.5%; foot 1.4%).
16. The overall risk of malnutrition
This is linked to a care plan, but the operational pathways can vary from centre to centre to take into account specific groups of patients and the available resources.
The ‘MUST’ frequently asked questions
Development and validation of the ‘MUST’
1. In which healthcare settings was ‘MUST’ piloted?
The reliability of ‘MUST’ was established by assessing extent to which the malnutrition risk obtained independently by different healthcare workers on the same group of patients agreed with each other (inter-rater agreement). A series of studies were undertaken in medical and surgical wards, outpatient clinics, nursing / residential homes and a GP surgery. Agreement was >95% in all studies. Most other screening tools have not been tested in this way and where they have, the level of agreement has generally been lower than with the ‘MUST’.
2. Has ‘MUST’ been validated for use in subjects with learning or physical disabilities? Are the BMI cut-off values relevant for this client group?
BMI is used as a general indicator of protein energy status and recommended for this purpose by national and international organisations. Whilst some clients with learning or physical disabilities were included in the pilot phase of ‘MUST’, the tool was not specifically validated in this client group. Research is required to assess if BMI reflects the same or different body composition in those subjects with learning or physical disabilities.
3. Is ‘MUST’ suitable for use in patients with renal or liver disease?
‘MUST’ has been designed for use in all care settings by all healthcare workers. There is no reason why it cannot be used in patients with renal or liver disease, but care should be taken when interpreting BMI and weight loss if fluid balance is disturbed (see details in the ‘MUST’ Report and ‘MUST’ Explanatory Booklet).
4. Why haven’t the cut-off points for BMI used in ‘MUST’ been adjusted for use in the elderly?
The lower BMI cut-off points for malnutrition risk used in ‘MUST’ are consistent with those given in a WHO report on loss of physiological function in relation to BMI. A wide range of BMI cut-off points (<17 kg/m2 to <24kg/m2) have been used to indicate malnutrition in older subjects. Use of these results in enormous differences in the prevalence of malnutrition in this population group and in the strategies and resources required to manage it.
Confusion appears to have arisen from the inappropriate extrapolation of BMI cut-off values obtained from public health initiatives to clinical practice. BMI cut-off values for public health are primarily intended for groups of subjects without overt disease whilst in clinical practice they are intended for those subjects with disease.
In public health, BMI is typically used to aid the prediction and prevention of mortality, often over many years, mainly from cardiovascular disease. In clinical practice, BMI is typically used to aid the prediction of current nutritional status and body function and the likely response to treatment, usually over a much shorter time frame.
Public health and clinical approaches may not yield the same BMI values or require the same nutritional interventions.
In the UK, public health surveys have not used the elevated lower cut-off values but have consistently used BMI of < 20 kg/m2 to indicate underweight in adults, including those individuals over 65 years of age. In USA, the 1990 Dietary Guidelines for Americans which suggested age specific BMI ranges were withdrawn in 1995 as it was recognised that other variables (e.g. smoking, lifestyle) affected mortality not just BMI.
In clinical practice, many professional organisations, agencies and healthcare workers recommend a BMI cut-off value of 18.5 – 20 kg/m2 to identify nutritional risk in a range of ages including older subjects who account for ~50% hospital population and 90% of those in nursing homes.
The cut-off values used in ‘MUST’ are based on physiological and clinical observations on loss of body function as BMI decreases, the apparently normal body function in many older subjects with a BMI >20 kg/m2 and randomised controlled trials showing the benefits of nutritional support in subjects, particularly those in the community with a BMI <20 kg/m2.
5. How was the score of 2 for the effect of acute disease derived?
There are 2 aspects to take into account when considering the effect of acute disease on malnutrition risk:
(i) No or virtually no food intake for more than 5 days i.e. starvation
(ii) The catabolic effect of acute disease.
During starvation, taller and heavier individuals tend to lose weight faster than those who are shorter and lighter. Hence men tend to lose weight faster than women. However, malnutrition risk is influenced more by the percentage weight loss than by actual weight loss. The same absolute weight loss results in a greater percentage weight loss in leaner individuals than in heavier subjects.
After 5 days of total starvation, subjects with an initial BMI of 17.5 – 18.0 kg/m2 lose close to 10% body weight; those between 20 – 25 kg/m2 lose about 6-8% body weight; and those with a BMI of ~ 35 kg/m2 lose about 5% body weight.
In the presence of acute disease, basal metabolic rate is increased but physical activity is decreased and an increase in energy expenditure may not occur. However, there is an increase in protein oxidation and nitrogen loss, therefore in the absence of fluid retention, the rate of weight loss and loss of lean body mass tends to be more rapid in the presence of acute disease. Typically the percentage weight loss in acute disease together with no or virtually no food intake for more than 5 days is comparable to > 10% over 3 –6 months. Hence a score of 2 has been assigned.
6. What is the evidence for the equal weightings given to the 3 criteria used in ‘MUST’?
Each of the 3 components of ‘MUST’ can occur independently or together. Each can have detrimental effects on physiological function and clinical outcome, therefore it is reasonable to assign an important weighting to all of them. The components vary in importance according to patient group, outcome variable and healthcare setting.
The predictive value of the individual components was independently assessed in a variety of healthcare specialities and settings. ‘MUST’ categorisation was found to be significantly related to mortality, length of stay in hospital and number of GP visits by patients in the community. The relative importance of each factor was found to vary with the care setting and type of patient (i.e. medical speciality), therefore, the MAG Committee decided to assign equal weightings to BMI, recent weight loss and acute disease effect in order to simplify use of the tool whilst retaining overall predictive validity.
7. Where can I obtain further information on the development and validation of the ‘MUST’?
“The ‘MUST’ Report” examines the need to screen, contains the evidence base for the criteria used in ‘MUST’ and describes the development and validation of the ‘MUST’. Copies can be purchased from the BAPEN office:
Tel: 01527 457850
8. Has ‘MUST’ been validated for use in children?
No. ‘MUST’ is only validated for use in adults.
Using the ‘MUST’
1. We would like to modify ‘MUST’ and incorporate it into our Trust documentation. To what extent can we change ‘MUST’?
- The core elements of ‘MUST’ should be retained and BAPEN /MAG acknowledged if ‘MUST’ is to be modified and incorporated into local documentation
- The tool should always be described as a nutrition screening tool and not an assessment tool
- The cut-off points and scores must not be changed
- If it is to be used in an acute hospital, all 3 steps should be included, but if it is to be used in other care settings then Step 3 (acute disease effect) may be omitted
- At least 1 alternative measurement should be included in order to calculate a height if this cannot be measured or obtained by recall. MAG would suggest ulna length
- Ideally ‘MUST’ BMI chart and weight loss tables should be available
- Local management guidelines can be inserted or referred to in Step 5.
2. What if a patient scores between 2 and 6?
There is currently insufficient information to make confident judgements on the severity of malnutrition in subjects with ‘MUST’ scores between 2 and 6. Guidance on how best to manage these patients should be obtained by undertaking a more detailed nutritional assessment in line with local policy.
3. Has the care plan given in ‘MUST’ been validated too?
The recommendations given in the care plan in “The ‘MUST’ Explanatory Booklet” are guidelines based on best practice and currently available evidence for the benefits of nutritional intervention. The guidelines can be replaced by your local guidelines / care plan.
4. Why doesn’t the care plan in the ‘MUST’ Explanatory Booklet recommend the use of food fortification?
Potentially food fortification could be of value but there is little evidence that such modification to the diet (especially fortification with single or multiple sources of macronutrients) translates to improved clinical outcome or function.
5. How accurate are the alternative measurements suggested in ‘MUST’?
It is always better to obtain an actual height or ask the subject how tall they are rather than use an alternative measurement to calculate a height. It should be possible to do this in the majority of subjects. However, if height cannot be obtained, use of any of the alternative measurements, whilst not resulting in an exact height, will provide a calculated height that is sufficiently close to the actual height to place the majority of subjects in the correct BMI band and result in a correct overall category of malnutrition risk. Ulna length is generally found to be the easiest and quickest alternative measurement to use.
6. Do I need copyright permission to reproduce ‘MUST’?
- The ‘MUST’ is freely available to use for non-commercial purposes.
- If you wish to adapt the ‘MUST’ in any way, by adding an NHS Trust logo for example, or changing the management guidelines, copyright permission must be sought, and a copy of the adapted version sent to the BAPEN Office. ‘MUST’ artwork can be supplied for printing purposes.
- If ‘MUST’ is to be used for commercial purposes, copyright permission must be sought and a licence agreement signed & a licence fee paid before original artwork is provided by BAPEN. File copies of the materials produced must be sent back to the BAPEN Office.
- If ‘MUST’ is to be incorporated into materials for which BAPEN endorsement is sought, then a written proposal together with a draft of the materials to be produced must be submitted to the BAPEN Office. Two months should be allowed for this process and a fee will be charged. A copy of the BAPEN logo and a statement of endorsement will be provided for inclusion in the materials. Final copies must be sent to the BAPEN Office.
- In every instance where ‘MUST’ is utilised (in print or on-line) the following wording must also appear:
- “The ‘Malnutrition Universal Screening Tool’ (‘MUST’) is reproduced here with the kind permission of BAPEN (British Association for Parenteral and Enteral Nutrition)”. An indication must be made somewhere on the documentation that for further information on ‘MUST’ see www.bapen.org.uk.
7. How much does the ‘MUST’ cost?
Copies of PDFs of the ‘MUST’ tool and “The ‘MUST’ Explanatory Booklet” can be downloaded free of charge from the BAPEN website: www.bapen.org.uk.
Additionally, printed copies of the ‘MUST’ tool (A5 and A4 sizes), “The ‘MUST’ Explanatory Booklet” and “The ‘MUST’ Report” can be purchased from the BAPEN office. For further information and prices contact:
Tel: 01527 457850
1. Why is nutritional screening necessary?
Early identification of patients who are nutritionally depleted (or likely to become so) is vital in order to provide timely and appropriate nutritional intervention. Nutritional screening should result in early identification of those patients who might have otherwise have been missed.
2. Who should I screen and when?
NICE recommend screening for malnutrition and risk of malnutrition across all healthcare settings. Patients should be screened:
- on admission to hospital and weekly thereafter
- at their initial out-patient appointment
- on admission to care homes or where there is clinical concern
- at initial registration at general practice surgeries, when there is clinical concern or at other opportunities e.g. health checks, flu injections.
3. We have our own nutrition screening tool, why should we change to using ‘MUST’?
If you already have a nutrition screening tool in use then there is no need to change to ‘MUST’ - especially if it is validated, reliable, easy and quick to use, and acceptable to patients and healthcare workers.
However, you may wish to review the evidence for the criteria used in your tool and perhaps think about comparing your tool with ‘MUST. If they identify the same subjects as being at risk of malnutrition then fine, but if not perhaps you should discuss changing to ‘MUST’ with your healthcare colleagues.
NICE suggest that nutritional screening should take into consideration body mass index (BMI), percentage unintentional weight loss and the time over which nutrient intake has been unintentionally reduced and/or the likelihood of future impaired nutrient intake. These parameters are the same as those in ‘MUST’ Steps 1-3.
4. How do I go about implementing nutritional screening?
Planning is fundamental to the successful implementation of nutritional screening in any healthcare setting. A number of steps should be considered e.g.
- Identify and secure your stakeholders - what’s in it for them?
- Set up a steering group
- Identify any resources required e.g. weighing and measuring equipment
- Agree actions and timelines
- Agree care plan and management of those identified as at risk
- Agree who will deliver the training and how will it be rolled out?
- Consider how training will be delivered on an on-going basis?
- Audit and review
5. What do I do once I have screened my patients?
The results of nutritional screening should always be linked to care plans and clear goals for nutritional intervention should be set and reviewed on an ongoing basis.
Step 5 of the ‘MUST’ provides guidance on the management of those patients identified as being at Low, Medium or High risk of malnutrition. This step can be adapted to fit with local nutrition guidelines or policies.
The results of screening should be communicated to members of the multidisciplinary team and across healthcare settings as the patient moves between primary and secondary care.
6. Are any training resources or materials available for me to use in the UK?
A number of the Medical Nutrition companies can support you with training and resources – contact your local representative for further information.
For further information on any other aspect of the ‘MUST’ please contact the BAPEN Office. Printed copies of all ‘MUST’ materials are available to purchase from the BAPEN office:
Tel: 01527 457850
Screening is a 'MUST' – a practical workshop
Practical Workshop (PDF). This document can be used as the basis for running a workshop on the use of MUST
Improving nutritional care workshop. This link is to the Royal College of Nursing Tools that were developed as part of their ‘Nutrition Now’ campaign in collaboration with the National Patient Safety Agency (NPSA) and BAPEN. The workshop documents have been designed to be used by anyone who works in a team and wishes to enhance nutritional care. They contain a practical structure for delivering a workshop, with thought-provoking evidence and ideas to enhance nutritional care and initiate change.
The 'MUST' Explanatory Booklet
The ‘MUST’ Explanatory Booklet has been designed to explain the need for nutritional screening and how to undertake screening using the ‘Malnutrition Universal Screening Tool’ (‘MUST’). It can also be used for training purposes.