Background/Purpose: Patients
with JIA are at risk of disability, pain and joint damage in the longer-term. Treating
toward clinically inactive disease (ID) has the potential to improve outcomes
and standardise the quality of care provided across different clinical
settings. A number of ID definitions have been developed for JIA.  Few studies
have compared the frequency of achieving ID across definitions in a single
patient population.

Methods:
Children were recruited to the Childhood Arthritis Prospective Study (CAPS), a
JIA prospective inception cohort established in 2001. Single and composite
definitions of ID and composite definitions of minimal disease activity (MDA)
were applied to the cohort at one year following first presentation (Table 1).
Composite definitions included Wallace’s preliminary criteria and cut-offs on Juvenile
Arthritis Disease Activity Score (JADAS) measures.   Multiple imputation was
used to account for missing variables at baseline and at one year.

Results: A
total of 1415 children were included.  At baseline, the median age was 7.7 years
and 65% were female. The most common ILAR subtypes were oligoarticular (50%)
and RF-negative polyarticular (21%) at one year. Median baseline JADAS71 score
was 11.

At one year, 1331
patients remained in the study. Sixteen (1.1%) patients had been discharged due
to low disease activity and a further 68 had been discharged for other reasons
or lost-to-follow-up.  At least one state of ID was achieved by 69% of patients
(Table 1). Estimates of ID ranged from 20% using Wallace’s preliminary criteria
to 48% using parental remission on JADAS71. Physician, parent and child-driven
JADAS cut-offs resulted in similar remission frequencies, with between 45%
(Physician JADAS10) and 48% (Parental JADAS71) of patients achieving these
states. There was very little difference between the frequency of remission
using JADAS10 and JADAS71 tools, with a 1% maximum discrepancy using
corresponding cut-offs.

MDA was achieved
slightly more frequently than ID, with 51% patients achieving MDA on JADAS71.
Other MDA definitions could only be applied to specific ILAR subtypes. In persistent
oligoarticular JIA, 66% achieved MDA although the frequency in patients with
extended oligoarticular, polyarticular or systemic JIA was lower at 50%.
However, only 47% achieved MDA using cJADAS which excludes the systemic disease
course.

Conclusion:
The frequencies of patients achieving MDA and ID varied greatly between
definitions, although a large proportion of children still had active disease
one year following diagnosis. Estimates from the JADAS71, JADAS10 and cJADAS10
were similar supporting the use of the more clinically feasible JADAS tools.
However the disparity in rates between the majority of measures has
implications for research and clinical practice, where distinctly different disease
states are being used as treatment targets in patients with JIA.