A recent article in the online publication for doctors called Rheumatology Network calls into question the commonly used outcome measures used in RA. The article, titled RA Outcome Measures Made Simple (or Not?), makes the argument that simpler measures of RA activity are needed.
Over the years, numerous measurement tools have been developed to help doctors determine extent of disease activity. These measures include the HAQ, DAS 28, CDAI, ACR 20, and RAPID 3 among others. These survey-type tools usually focus on joint activity, swelling, pain levels, disability. Some, like the DAS 28 (28 refers to 28 joints – the number of RA affected joints), include blood tests in the assessment. An online DAS 28 tool is available for doctors and patients. If you are a RA patient, your rheumatologist may have used one or more of these tools for diagnosis and to monitor treatment effectiveness. These tools are also used for drug development and testing.
Over the years, these measurement tools have been the target of much research in terms of validation and correlation with the disease (e.g. Radner, et al, 2014). Because they have been shown to provide a modicum of usefulness, they remain in vogue by the rheumatology community. However, in spite of their usefulness and relationship with RA disease components, the ability of these surveys to accurately and completely paint a picture of the disease remains in question. A recent study by Cheung et al (2013) demonstrated that doctors and patients sometimes agree, and sometimes disagree on some of these measures. Sometimes doctors and patients completely disagree (see Castrejón, et al, 2014). In a research paper that I helped present at the American College of Rheumatology conference last year, it was found that the commonly used HAQ tool did not always adequately capture disease impact and activity in patients.
When it comes to subjective measures like impacted joints and bodily function, it’s oftentimes difficult to develop tools that measure variables with 100% accuracy. One would like to think that measurements of biological chemicals involved in disease processes would be more accurate, But that is not always the case and they are also difficult to develop with 100% accuracy (see this article). The bottom line is that researchers need to continue to work on developing useful and accurate measures for RA disease activity. Only then can diagnosis and treatment options be maximized.