Severity

For Medical Students

What It Tests

Asking how bad the pain is tests how much the symptom is costing the patient. It does not test how much damage there is.

Those two diverge in both directions and routinely. A severely degenerate knee can be mildly symptomatic and a structurally minor problem can be disabling.

Severity is therefore a measure of impact rather than of pathology, and it is the measure that determines whether anything needs doing.

How It Is Performed

Ask what the pain stops them doing, rather than asking for a number out of ten.

A number is easy to record and hard to interpret, because patients calibrate differently and the same number means different things in different people.

Ask about specific activities: walking distance, stairs, sleep, work, and whatever they used to do for enjoyment.

Ask what painkillers they take, how often, and whether they help, since that is a behavioural measure of severity rather than a reported one.

Ask whether it is getting worse, better or unchanged, because the trajectory matters more than the level.

What a Positive Means

Pain that wakes the patient at night is a severity marker and shifts the differential. 4.2.13 covers it.

Pain that has stopped work or stopped walking is severe regardless of what number the patient offers.

Pain requiring regular opiates in a knee with modest findings should raise sensitisation or a cause outside the knee rather than more imaging.

Pain the patient describes as severe but which has not changed any activity is a different presentation and is worth exploring rather than discounting.

MRCS Level

What a Positive Means

The expected framing is that severity determines urgency and threshold, not diagnosis.

A patient whose function is preserved has time, whatever the imaging shows.

A patient whose function has collapsed needs something done, and what is done depends on the diagnosis rather than on the severity.

Severity disproportionate to the findings is itself a clinical finding, and the correct response is to broaden the assessment rather than to repeat the imaging. 4.2.1 covers the same point for pain generally.

Scored instruments exist to make this comparable between visits and between patients, and they are the subject of chapter 4.22. 4.22.8 covers their use in practice.

How Good It Is

Severity performs badly as a guide to pathology and well as a guide to what the patient will accept.

A patient with mild symptoms will decline a long rehabilitation and a patient with severe symptoms will accept one, and that is the decision severity actually informs.

Function based questions outperform numerical scales, because an activity is a fact and a number is a judgement.

Comparing severity between patients is unreliable. Comparing it in the same patient over time is reliable, which is why the trajectory is the useful measure. 4.1.8 covers the record that makes that comparison possible.

FRCS Level

How Good It Is

At decision level severity is the main determinant of threshold, and under-weighting it is the commoner error.

An operation offered to a patient whose symptoms are mild risks a result that is mechanically successful and subjectively worse, because there was little to improve and a recovery to endure.

An operation withheld from a patient whose function has collapsed on the grounds that the imaging is unimpressive ignores the measure that matters.

The most useful single severity question before elective surgery is what the patient expects to be able to do afterwards, because expectation predicts satisfaction more reliably than any structural measure. 4.20.8 covers the arthroplasty version.

Where It Misleads

Severity misleads when it is taken as a proxy for pathology, which is the error running through this page.

It also misleads when under-reported. Stoical patients, older patients and patients who have adapted their lives systematically understate it, and the remedy is to ask about activities they have abandoned rather than activities that hurt.

It misleads when over-reported in a context with consequences, which is a reason to use function and behaviour rather than numbers. 4.23.7 covers medicolegal assessment.

And a severity that fluctuates widely from day to day with no mechanical pattern points away from a structural cause.

Fellowship Level

Where It Misleads

In referred and revision practice severity is frequently the reason for referral and the least useful part of the letter, because it has no comparator attached.

The useful version is severity relative to before the last intervention, and that comparison usually has to be reconstructed in the consultation because it was not recorded. 4.1.8 covers the record.

A patient worse after an operation than before it is a different problem from one who is better but not better enough, and the plans diverge completely.

Severe pain with no mechanical pattern after multiple operations is the presentation most likely to receive a further operation and least likely to benefit, and this chapter says so on several pages because it is the commonest avoidable harm in the subject.

No figure here supports that claim. It is standard teaching and the numbers were refused under decision 023.