Exploring shared characteristics of different knee pain measurement questionnaires
Full reference: Georgopoulos V, Smith S, McWilliams DF, Steultjens MPM, Williams A, Price A, Valdes AM, Vincent TL, Watt FE, Walsh DA. Harmonising knee pain patient-reported outcomes: a systematic literature review and meta-analysis of Patient Acceptable Symptom State (PASS) and individual participant data (IPD). Osteoarthritis Cartilage. 2023 Jan;31(1):83-95. doi: 10.1016/j.joca.2022.08.011. Epub 2022 Sep 8. PMID: 36089231.
Knee pain is a common problem across populations. Osteoarthritis or sporting injuries often cause this type of pain. Several treatments are available and more are being developed. There are several questionnaires that measure knee pain and help clinicians or researchers decide whether their proposed treatment works. Although treatments can provide pain relief, such improvement in pain is often not enough to be useful to the person taking the treatment. Despite using treatments, people often continue having unacceptable knee pain.
Patient Acceptable Symptom State (PASS) was proposed to better understand whether change in pain as a result of treatment leads to an acceptable state. PASS refers to a level of pain below which people would consider their pain to be acceptable if they had it for the rest of their life. However, given the numerous pain questionnaires available, that value can be different for each questionnaire, leading to challenges in comparing results between treatments or research studies.
Versus Arthritis has funded many studies that investigate knee pain and is interested to bring the results from all those studies together in order to understand how best to help people with such pain. With their support, we set out to find what PASS values have been proposed so far, and explore whether they are similar across measurement tools. To do so, we reviewed the literature and we found PASS values for four different questionnaires and many different causes of knee pain. To compare these questionnaires, we converted each of them to a 0-100 scale (0: no pain, 100: extreme pain). A value of 30/100 is similar between questionnaires, but we found that what people consider as acceptable pain differed between different conditions with knee pain.
We then used data from four studies in which people experiencing knee pain completed at least two different knee pain questionnaires. When looking at entire study populations, we found no significant differences in reported pain values between questionnaires. However, when we looked at pain severity or PASS levels for each participant, we found that different questionnaires give noticeably different answers for the individual. Our findings lead us to realise that people experience pain in different ways. Some treatments might work better for some people than others. Our results also suggest that different measurement tools should be used for different causes of knee pain. More research is needed to develop strategies that works for everyone.