To begin the validation process of the preliminary criteria for inactive disease (ID), clinical remission on medication (CRM), and clinical remission off medication (CR) in children with select forms of juvenile idiopathic arthritis (JIA).
We used the OMERACT filter paradigm to estimate the validity of the criteria within each of the filter's 3 components: truth, discrimination, and feasibility, in 5 categories of JIA: systemic arthritis, persistent and extended oligoarthritis, and rheumatoid factor-positive and negative polyarthritis. Data sources for determining validity estimates included a Delphi questionnaire survey sent to 246 pediatric rheumatologists in 34 countries, a consensus conference attended by 20 senior pediatric rheumatologists representing 9 countries, a retrospective chart review of 437 patients with JIA from 3 tertiary care clinics who had been followed between 4 and 22 years, and the literature.
Truth component: face and content validity. These aspects of validity were largely established via the Delphi questionnaire exercise and the consensus conference. Using an 80% consensus level, participants felt that a set of non-redundant variables could effectively differentiate the clinical states of ID, CRM, and CR. Criterion validity could not be irrefutably established because no gold standard for inactive disease exists for JIA. As an alternative, published investigations of remission in JIA were used to estimate concurrent and convergent validity, as surrogates for criterion validity and as indicators of overall construct validity. Correlational analyses revealed the new criteria to have good construct validity. Discrimination component: the criteria demonstrated moderate to high levels of classification, prognosis, and responsiveness (sensitivity to change) using data from the chart review. Patients who were able to attain CR remained disease-free for substantially longer periods than did those who attained only ID or CRM. Responsiveness was evidenced by the ability of the criteria to allow movement of most patients between the disease states, consistent with what is known of the course of the disease. Feasibility component: Results of the Delphi and consensus conference produced a set of criteria that are easily, quickly, and inexpensively completed in the physician's office, and present minimal or no risk to the patient.
The preliminary criteria demonstrated moderate to excellent validity characteristics in some, but not all components of the OMERACT filter. Prospective validation studies are under way.