The above title, (kindly provided by the planning committee) carries some duplicity. Two main topics come to mind:
“Is better classification of remission possible if we use modern imaging techniques?” And:
“How do we combine the results of modern imaging techniques with the classification provided by the RA remission criteria?”
Other presentations will highlight the potential of new imaging techniques in patients with low disease activity and remission. I will focus on issues of Truth, Discrimination and Feasibility (criteria of the so-called OMERACT Filter to assess the applicability of measures in studies*) in the design of the new remission criteria.
ACR and EULAR installed a committee and requested a stringent definition that included joint counts and acute phase proteins, but not include physical function or treatment. The committee faced conceptual and practical issues and made choices that helped shape the current definition.
Conceptually, remission can be defined as “the state of absence of disease activity in patients with a chronic illness, with the possibility of return of disease activity” (Wikipedia). The committee considered that the remission definition is intended for use in all trials and chose to operationalize “absence of disease activity” as the ideal outcome of the disease as assessed by routine clinical measures. Disease activity is a construct needed because our understanding of the disease is incomplete. In a fully understood disease remission equals “absence of disease”. New diagnostic techniques (including imaging but also immunohistopathology and soluble biomarkers) can increase understanding and expand the construct of disease activity, but also increase detection of disease activity. In addition they can also increase detection of damage not seen on conventional radiographs, and sometimes predict where (conventionally detectable) damage will develop.
Expanding the construct implies that absence of disease activity and damage can also be better documented by such techniques. However, here the tradeoffs begin, situated in all criteria of the OMERACT Filter:
Truth: is the data generated by, say, ultrasound fully incorporated in the construct?
Discrimination: is the measure sufficiently reliable and sensitive to change?
Feasibility: is the measure applicable in terms of time, cost and interpretability?
The utility of defining remission lies in its prognostic value, and the ACR/EULAR definition was studied to see if it predicted a good outcome (good and stable function and no progression of damage up to 2 years). Although sensible and feasible, real outcome of RA should be measured over a much longer time span and include hard endpoints such as work disability, joint replacement surgery, and death.
As experience over the last 20 years has shown RA outcome has already much improved by current treatment that unfortunately does not lead to long-term remission by any definition. So what do we need most? New techniques to more accurately demonstrate lack of disease activity, or treatment that induces a long-lasting state of (near) absence of disease activity reliably in the majority of RA patients?
I would argue the latter, with one important exception: RA patients that experience rapid radiographic progression early in the disease may strongly benefit from early detection. In this setting the value of new techniques needs to be proven.
In conclusion: better classification of absence of disease activity is possible with newer techniques, but getting most patients in a state of clinically defined minimal disease activity or remission is our more urgent task. New techniques are best tested at treatment start or in the initial phase of response to help us treat poor-prognosis patients better.
*Boers M, et al. The OMERACT Filter for outcome measures in rheumatology. J Rheumatol 1998;25:198-9.
Disclosure of Interest None Declared
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