Why rating your pain out of 10 is tricky

That common upper anchor in rating scales — 'worst pain imaginable' — is a problem because how can anyone imagine it?

- Joshua Pate, Dale J. Langford and Tory Madden

"It's really sore," my (Josh's) five-year-old daughter said, cradling her broken arm in the emergency department. "But on a scale of zero to 10, how do you rate your pain?" asked the nurse.

My daughter's tear-streaked face creased with confusion.

"What does 10 mean?"

"Ten is the worst pain you can imagine." She looked even more puzzled.

As both a parent and a pain scientist, I witnessed first-hand how our seemingly simple, well-intentioned pain rating systems can fall flat.

WHAT ARE PAIN SCALES FOR?

The most common scale has been around for 50 years. It asks people to rate their pain from zero (no pain) to 10 (typically, "the worst pain imaginable").

This focuses on just one aspect of pain — its intensity — to try and rapidly understand the patient's whole experience.

How much does it hurt? Is it getting worse? Is treatment making it better?

NARROW TOOL FOR A COMPLEX EXPERIENCE

Consider my daughter's dilemma. How can anyone imagine the worst possible pain? Does everyone imagine the same thing? Research suggests they don't. Even kids think very individually about that word "pain".

People typically — and understandably — anchor their pain ratings to their own life experiences.

This creates dramatic variation. For example, a patient who has never had a serious injury may be more willing to give high ratings than one who has previously had severe burns.

"No pain" can also be problematic. A patient whose pain has receded but who remains uncomfortable may feel stuck: there's no number on the zero-to-10 scale that can capture their physical experience.

Increasingly, pain scientists recognise that a simple number cannot capture the complex, highly individual and multifaceted experience that is pain.

WHO WE ARE AFFECTS OUR PAIN