The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).
The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is a popular patient reported outcome measure used for the evaluation of knee osteoarthritis.
Since its development, WOMAC has been used extensively in research studies, undergone rigorous psychometric validation and is frequently utilized in many clinical trials. Additionally, the WOMAC has been recognized by the Outcome Measures in Rheumatoid Arthritis Clinical Trials group (OMERACT) and Osteoarthritis Research Society International (OARSI), alongside many other regulatory bodies and agencies.
Developed over 30 years ago, the WOMAC has been revised multiple times to its most current version (version 3.1). Over time the questionnaire has changed but in its present form, it consists of 24 items divided into three (3) subscales: pain (5 items), stiffness (2 items) and physical function (17 items). Patients are asked a range of questions about their ability to carry out daily activities such as using the stairs, rising from sitting, lying in bed and conducting light or heavy domestic duties. All the items are scored on a scale of 0-4 (lower scores indicate lower levels of symptoms or physical disability) and values are summed up for a combined WOMAC score. While this is the most common method used to calculate the final score other methods of aggregating scores have also been used.
The relatively simple nature of the WOMAC survey means that it can be completed in a short amount of time and scored in just 5-10 minutes.
Strengths
The WOMAC is an exceedingly popular measure, highlighted by its extensive use in both observational/epidemiological studies and its availability in over 65 languages. The questionnaire can also be used for a variety of different conditions. Originally the WOMAC was developed for use amongst patients with knee and/or hip osteoarthritis, but it has also been used for patients with low back pain, rheumatoid arthritis, juvenile rheumatoid arthritis, systemic lupus erythematosus and fibromyalgia.
The WOMAC has excellent usability. It’s relatively short when compared to other PRO measures like the KOOS and the OKS. Its popularity, availability in multiple formats and easy scoring methodology make it a great choice for the evaluation of patients with hip and knee osteoarthritis.
Considerations
A consideration of the WOMAC is that the stiffness subscale (one of the three scoring subscales) has been shown to have low test-retest reliability and the physical function subscale is limited in its ability to detect change.
License
Paid. The WOMAC measure requires a license. To learn more or to obtain a license, please visit their website: www.womac.com/contact/index.php.
Sources | Rasch analysis of the Western Ontario MacMaster questionnaire (WOMAC) in 2205 patients with osteoarthritis, rheumatoid arthritis and fibromyalgia. | Osteoarthritis Index delivered by mobile phone (m-WOMAC) is valid, reliable and responsive | (3-C) Patt JC, Mauerhan DR. Outcomes research in total joint replacement: a critical review and commentary.
