“Results are provided in the context of where someone falls in relation to the general population.”
PROMIS can measure symptoms and functional status in people with RA, such as fatigue, sleep, emotional distress and participation in everyday activities. Results are reported using T-scores in which all scales have a mean of 50 and standard deviation of 10. Using a common metric across all scales makes it easier to interpret and compare results across visits, between RA patients and those with other medical conditions.
The ability to use such measures as PROMIS to quantify patient reports that traditionally have been seen as subjective, and therefore harder to quantify, comes from the use of an advanced statistical methodology, called item response theory. Dr. Bartlett likens the methodology to the way standardized tests are constructed. “The answer you give on one question will determine the next question you get, and the computer will give you questions that help pinpoint what is being evaluated,” she says.
When measuring fatigue, for example, the computer algorithm draws on 90 questions in the PROMIS item bank to find the right set of questions (often four to six) that can precisely identify fatigue level.
“This is a new way of measuring things,” says Dr. Bingham, adding that results are able to quantify for physicians not only how much fatigue patients are experiencing, but also how it is affecting their overall quality of life.
Because the measures are very sensitive, even when measuring very low or high levels of a symptom, this approach offers new insight into RA. For example, even when patients are in remission or experiencing low disease activity, PROMIS measures indicate that a subset was experiencing debilitating levels of fatigue that affected their ability to work and participate in life roles. Many patients also told the investigators that severe fatigue was one of the earliest signs of a major RA flare.
“The question becomes, ‘Are we managing people as well as we can, or do we need to think about also measuring other key symptoms that really affect how people feel and function?’” Dr. Bingham says.
Treat the Whole Patient
An answer to that question comes from those who live with RA daily. “Patients with rheumatoid arthritis are whole people,” says Ms. Leong. “Just to address the flare is not to address the whole person and the family, work and social context in which we live.”