MUST Score Negligence: When Does Legal Risk Arise?
- Rick Miller
- Feb 17
- 3 min read
The Malnutrition Universal Screening Tool appears in almost every hospital malnutrition case I review as an expert witness dietitian.
A score of 2 is often described as “high risk.”
But does that automatically create legal exposure?
The answer is more nuanced.
Whilst MUST is not the only nutritional screening framework used across the UK, it remains the most commonly encountered tool in acute hospital litigation.
The legal analysis, however, is not confined to the name of the screening tool used, but to the reasonableness of the response to the documented nutritional risk.
MUST Score Negligence: When Does a Score of 2 Trigger Legal Risk?
A distinction frequently misunderstood in litigation.
MUST is a screening tool. It is not:
A diagnosis
A treatment plan
A dietetic assessment
A metabolic risk calculation
It is designed to identify patients at risk of malnutrition based on:
BMI
Unplanned weight loss
Acute disease effect (nil intake >5 days)
A score of 2 or more indicates “high risk” of malnutrition.
From a clinical governance perspective, this should trigger:
Escalation
Monitoring
Referral (depending on local policy)
However, the presence of a MUST score ≥2 does not automatically mean negligence if deterioration later occurs.
The legal question is more structured than that.
Where MUST Score Negligence Risk Begins
Legal risk emerges when there is a mismatch between:
The documented level of nutritional risk and
The documented response to that risk
In practice, the courts tend to focus on four key questions.
1. Was the score accurate?
Errors in BMI calculation, missing historical weight, or incorrect recording of nil-by-mouth periods can distort risk categorisation.
If the score was inaccurate, the subsequent escalation pathway may also be flawed.
2. Was there an appropriate response?
A score of 2 will often require:
Referral to dietetics (urgent or routine depending on local protocol)
Food and fluid charting
A documented monitoring plan
If no action follows, that absence becomes legally relevant.
3. Was deterioration foreseeable?
Not all patients with MUST ≥2 deteriorate. Many remain clinically stable.
The relevant legal question is not whether deterioration occurred, but whether it was reasonably foreseeable at that time.
Foreseeability sits at the centre of breach and causation analysis.
4. Would earlier intervention have altered outcome?
Even where delay is established, causation remains a separate and critical consideration.
The court must determine whether earlier dietetic input would, on the balance of probabilities, have prevented:
Metabolic decompensation
Starvation ketoacidosis
Functional decline
Death
This is frequently where cases succeed or fail.
Routine vs Urgent Referral in MUST Score Negligence Cases
One common area of dispute is whether referral should have been “routine” or “urgent.”
Hospitals typically triage referrals according to:
MUST score
Clinical stability
Current intake
Competing medical acuity
From a medico-legal perspective, the key issue is not whether a referral was immediate, but whether the timing was reasonable in the clinical context.
A clinically stable patient with chronic low BMI may not require same-day review.
A patient who is nil by mouth, metabolically compromised, or showing signs of acute deterioration may.
The distinction is fact-sensitive and requires careful analysis of the clinical picture at the time, not in hindsight.
Retrospective Interpretation and MUST Score Negligence
In litigation, MUST scores are often scrutinised retrospectively with knowledge of the eventual outcome.
Where a patient later develops severe metabolic complications, earlier screening documentation may appear more concerning than it did contemporaneously.
However, hindsight bias must be avoided.
The correct legal test is not:
“Did the patient deteriorate?”
It is:
“Would a reasonable and responsible body of dietetic opinion, acting logically at the time, have escalated differently?”
That is a Bolam/Bolitho analysis — not a retrospective moral judgement.
Common Documentation Vulnerabilities
Across cases, recurring documentation issues include:
No record of intake despite high MUST
Referral made but no evidence of triage reasoning
Referral triaged but not clearly documented
No recorded review plan
No evidence of re-screening following deterioration
In many instances, the clinical care may have been reasonable, but the documentation does not clearly demonstrate that.
In court, absence of documentation can significantly weaken otherwise defensible care.
MUST Is a Trigger, Not a Verdict
It is important to emphasise that MUST is a screening trigger.
It does not:
Automatically require artificial feeding
Mandate TPN
Predict starvation ketoacidosis
Guarantee poor outcome
Escalation decisions must consider:
Underlying pathology
Prognosis
Capacity
Surgical planning
Overall medical stability
A MUST score should inform clinical judgement, not replace it.
Conclusion
A MUST score of 2 does not automatically trigger negligence.
Legal risk arises when documented high nutritional risk is met with no documented response, or when deterioration was reasonably foreseeable and not addressed.
In litigation, the central questions remain:
Was the response reasonable at the time?
Was deterioration foreseeable?
Would earlier intervention have altered outcome?
The number alone rarely determines liability.
The reasoning behind the response does.
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