What is the WOMAC index?
The WOMAC index (Western Ontario and McMaster Universities Osteoarthritis Index) is a questionnaire in which people with knee or hip osteoarthritis rate their own symptoms. It covers three areas: pain, stiffness and everyday physical function.
The WOMAC index explained simply
In osteoarthritis trials it is not enough to note "less pain". Researchers need an outcome measure that can be compared across groups and studies. That is what the WOMAC index (also called the WOMAC score) has been used for over several decades.
The classic questionnaire has 24 questions spread across the three areas. Participants answer looking back over the past 48 hours, usually on a scale from "none" to "extreme".
Structure of the WOMAC index
The three domains and typical items.
| Domain | Items | Example |
|---|---|---|
| Domain Pain | Items 5 | Example Pain when climbing stairs or at night in bed |
| Domain Stiffness | Items 2 | Example Stiffness after waking up |
| Domain Physical function | Items 17 | Example Putting on socks, rising from a chair, shopping |
The WOMAC index in curcumin studies
When you read about studies on curcumin in knee osteoarthritis, you almost always meet the WOMAC index. A well-known example is a trial with 367 participants comparing a turmeric extract (Curcuma domestica) with ibuprofen over four weeks. WOMAC scores improved in both groups; the difference between them was small, with fewer stomach complaints in the extract group.
Meta-analyses pool such results and often report a change in the WOMAC score. Note that the studies are small to medium in size, differ in dose, product and duration, and results are not uniform. These are investigations, not proof that curcumin treats osteoarthritis.
Strengths and limits
- Strength: the questionnaire is standardised, well validated and makes studies comparable.
- Limit: it measures subjective experience. Placebo effects and expectations can influence scores, which is why double-blind studies with a control group matter.
- Limit: it says nothing about cartilage loss on X-ray or MRI.
Frequently asked questions about the WOMAC index
What is a good WOMAC score? The lower, the milder the symptoms. Because scaling and conversion (for example to 0 to 100) differ between studies, absolute numbers can only be compared within the same study.
When is a change considered relevant? Research discusses the size of difference at which patients actually feel an improvement (the "minimal clinically important difference"). A statistically significant difference is not automatically noticeable.
Can I fill in the questionnaire myself? The questionnaire is freely accessible and also used in clinics. It serves to document progress, not to make a diagnosis or choose a therapy on your own.
Are there alternatives? Yes, such as the KOOS for the knee or simple pain scales. In curcumin studies, a visual analogue pain scale (VAS) often appears alongside the WOMAC.
The WOMAC index is a research instrument and does not replace a medical diagnosis. If joint symptoms persist, see a doctor. This is not medical advice.
