In today’s evidence-based medicine, patient satisfaction is important, but so are other measurable outcomes based on change in symptoms or physical function. In a recent study by physical therapists, three tools were used to measure change in knee function. Results were compared by looking at the reliability and responsiveness of these three tools. All patients (168 total) in the study had a diagnosis of knee osteoarthritis.
The three tools compared included the most widely used scale that you mentioned: the Western Ontario and McMaster Universities Osteoarthritis Index or WOMAC. The other two patient surveys were the Knee Outcome Survey (KOS) and the Lower Extremity Functional Scale (LEFS).
Each one of these self-report instruments measures function in slightly different ways. For example, the WOMAC looks at pain during activities, stiffness after prolonged positions, and ability to perform movements like standing up from a sitting position, dressing self, going up and down stairs, and walking. The KOS assesses limitations caused by pain, swelling, and joint instability. The LEFS looks more at the degree-of-difficulty someone has performing specific tasks during activities of daily living.
Everyone in the study completed all three surveys before and after treatment. Treatment consisted of a physical therapy program of leg strengthening, stretching, balance, and agility exercises. The exercise program took place twice a week for six to eight weeks. Patients were followed for up to one-year at regular intervals (two months, six months, 12 months).
The results showed that to measure change in knee function, all three tools are reliable and responsive. Therapists using these self-reported instruments may get slightly different information but all three surveys will reflect change and can therefore be used to obtain outcome measures. There was a trend observed with all three tools: the longer the follow-up, the less reliable the tools were to measure patients’ responsiveness to treatment.
There may be some specific reasons for this trend. For example, as people improve there may be less change occurring making it more difficult to measure change with these particular questions. There may also be differences in patient osteoarthritis that contribute to reduced observations of change. For example, someone with acute arthritis versus someone with a chronic condition may not respond to treatment in the same way. More studies are needed to examine these factors more closely but for now you can be assured that using any of these three tools for patients with knee osteoarthritis may help you measure results.