Estimates for juvenile idiopathic arthritis differ widely depending on which set of criteria doctors use.
Many children with juvenile idiopathic arthritis have persistent disease activity a year after first presenting with symptoms.
Established targets for treatment in juvenile idiopathic arthritis cannot be compared directly if they use different outcome criteria.
Kimme L. Hyrich, M.D., Ph.D., of the University of Manchester in the United Kingdom, and colleagues, point out that because of the lack of consensus in diagnostic criteria, “the same child could be classified as ‘in clinically inactive disease’ or having active disease at the same time point between clinicians or hospitals.”
Juvenile idiopathic arthritis is the single most common rheumatic disease affecting children. It is very challenging to define clinically inactive disease and or minimal disease activity since there is no diagnostic test for either and much variability exists in proposed diagnostic criteria.
The authors see developing consistent criteria for clinically inactive disease and minimal disease activity and the standardization of outcome measures as crucial in establishing valid target to treat strategies for children with idiopathic arthritis. They present their findings in a recent Annals of the Rheumatic Diseases article.
The authors wrote: “These differences highlight that the same child could be classified as ‘in CID’ or having active disease at the same time point between clinicians or hospitals. Future work needs to explore which treatment target predicts better long-term prognoses in JIA.
“The current study highlights that even published targets intended to capture the same construct identify different groups of children. Results from studies using different outcome criteria therefore cannot be compared directly. In addition, if used as targets in clinical practice, using different targets may result in overtreatment or under treatment.”
1,415 children with juvenile idiopathic arthritis were included in this inception cohort study. The authors defined the outcomes as no active joint involvement and a score of zero on the physician or parental global evaluation survey.
76% or enrolled children met clinically inactive disease or minimal disease activity criteria with more (48 to 61%) meeting minimal disease activity criteria than clinically inactive disease criteria.
Physicians and parents assessments were in concordance only 35% of the time with regards to a score of zero on the global assessments.
When the juvenile arthritis disease activity score and clinical juvenile arthritis disease activity score were compared the authors found nearly 100% overlap with both identifying 38% of children as in clinically inactive disease states at 1 year. Fewer children met clinically inactive disease criteria when Wallace’s preliminary criteria were utilized (25%) with only 44% overlap between Wallace’s and Juvenile arthritis
disease activity score groups.
Across all International League of Associations for Rheumatology subtypes outcome criteria were similar with children achieving no active joints more often than minimal disease activity or clinically inactive disease on juvenile arthritis disease activity and Wallace’s measures.
Implications for physicians
The variability of published targets of treatment in juvenile idiopathic arthritis makes it difficult to treat successfully.
The authors believe that, “using different targets in clinical practice may result in overtreatment or under treatment.”
Current outcomes measures are falling short with broad achievement of clinically inactive disease and minimal disease activity reaching only 30% and 50% respectively.
Current data support the use of the clinical juvenile arthritis disease activity score when assessing for clinically inactive disease.
The Medical Research Council, Arthritis Research UK and National Institute for Health Research provided funding. The authors declared no competing interests.
Stephanie J W Shoop-Worrall, Suzanne M M Verstappen, Eileen Baildam, et al. “How common is clinically inactive disease in a prospective cohort of patients with juvenile idiopathic arthritis? The importance of definition,” Annals of the Rheumatic Diseases. Published online 2017;0:1–8. doi:10.1136/annrheumdis-2016-210511