1 Before you use it
What it is
A 100 mm line, marked by the patient, measured by you. Same construct as the NPRS, different mechanics — and the mechanics are why it is second choice on placement.
When to reach for it
When a protocol, a research project or a placement site specifically asks for it. Otherwise use the NPRS.
Worth knowing because it appears constantly in the literature — a student reading a trial needs to recognise it.
Patterns it serves · 134
2 Giving it
Scoring
The patient marks the line; you measure the distance in millimetres from the left anchor. Score 0–100.
It requires paper, a ruler and good vision. The NPRS can be asked over a phone.
What it doesn’t measure
Same limits as the NPRS: no function, no interference, no distress. And it adds an administration burden the NPRS doesn't.
Repeat it
3 Reading the score
Interpreting it
Interpreted the same way as the NPRS: change against the patient's own baseline.
Do not convert between VAS and NPRS as if they are interchangeable point-for-point. They correlate; they are not the same scale.
Is the change real?
On placement
Knee OA. VAS 62 mm at intake, 45 mm at 6 weeks, measured with a ruler from the left anchor.
Read it as 17 mm down — 1.7 points on a 0–10 scale — over the verified MCID of about 1.4 points (measured in knee osteoarthritis). Meaningful. Don't convert it into an NPRS figure and compare across; they correlate and they are not the same scale.
Do record the millimetres, and read them against function and the 24-hour behaviour before you conclude anything from a pain number alone.
Student trap. Eyeballing the mark instead of measuring it. If you are not using a ruler, you are using a worse NPRS.
Official source: null. We don't host the form.
This is a learning tool. It does not diagnose patients and does not replace your clinical educator.
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