Development and validation of a composite disease activity score for measurement of muscle and skin involvement in juvenile dermatomyositis.

OBJECTIVE: To develop a composite DAS for JDM and provide preliminary evidence of its validity. METHODS: The Juvenile DermatoMyositis Activity Index (JDMAI) is composed of four items: physician's global assessment of overall disease activity; parent's/child's global assessment of child's wellbeing; measurement of muscle strength; and assessment of skin disease activity. The score of the JDMAI is the arithmetic sum of the scores of each individual component. Six versions of the JDMAI were tested, which differed in the tools used to assess the third and fourth items. Validation procedures were conducted using three large multinational patient samples including a total of 627 patients. RESULTS: The JDMAI was found to possess face and content validity, good construct validity, satisfactory internal consistency (Cronbach's alpha = 0.58-0.89), fair responsiveness to clinically important change (standardized response mean = 0.82-3.12 among patients improved) and strong capacity to discriminate patients judged as being in the state of inactive disease or low, moderate or high disease activity by the physician (P < 0.001) or whose parents were satisfied or not satisfied with the course of their child's illness (P < 0.001). Overall, the six versions of the JDMAI showed similar metrological performances in validation analyses. CONCLUSION: The JDMAI was found to possess good measurement properties in a large population of patients with a wide range of disease activity, and is, therefore, suitable for use in both clinical and research settings. The final version of the JDMAI will be selected after its prospective validation.

Development and Testing of a Hybrid Measure of Muscle Strength in Juvenile Dermatomyositis for Use in Routine Care.

OBJECTIVE: To develop and test a hybrid measure of muscle strength for juvenile dermatomyositis (JDM), which is based on the combination of the Manual Muscle Testing in 8 muscles (MMT-8) and the Childhood Myositis Assessment Scale (CMAS) but is more comprehensive than the former and more feasible than the latter. METHODS: The hybrid MMT-8/CMAS (hMC) is composed of all 8 items of the MMT-8 and 3 items of the CMAS: time of head lift, assessment of abdominal muscles, and floor rise. The score ranges 0-100, with 100 indicating normal muscle strength. Validation procedures were conducted using 3 large multinational patient samples, including a total of 810 JDM patients. RESULTS: The hMC revealed face and content validity, good construct validity, excellent test-retest reliability (intraclass correlation coefficient = 0.99), and internal consistency (Cronbach's α = 0.94), strong responsiveness to clinical change over time (standardized response mean = 0.8 among patients judged as improved by the caring physician), and satisfactory capacity to discriminate patients judged as being in the states of inactive disease or low, moderate, or high disease activity by the physician (P < 0.001) or patients whose parents were satisfied or not satisfied with the illness course (P < 0.001). CONCLUSION: The hMC was found to possess good measurement properties in a large population of patients with a wide range of disease activity and severity. The new tool, which is primarily intended for use in routine clinical care, should be further tested in other populations of patients evaluated prospectively.

Performance of QuantiFERON®-TB Gold In-Tube assay in children receiving disease modifying anti-rheumatic drugs.

BACKGROUND: To evaluate the performance of the Quantiferon®-TB Gold In-Tube (QFT-IT) interferon (IFN)-γ assay for the detection of latent tuberculosis infection (LTBI) in children receiving anti-rheumatic treatment in a tertiary referral hospital of Northern Greece. METHODS: A total of 79 consecutive children receiving anti-rheumatic treatment [of which 18 screened prior to antitumor necrosis factor (TNF)-α treatment] were tested using Mantoux tuberculin skin test (TST) and QFT-IT. Association of both tests with risk factors for latent tuberculosis and Bacillus Calmette-Guerin immunization was determined. Influence of age, TNF-α inhibitors, systemic corticosteroids, conventional disease modifying anti-rheumatic drugs (DMARDs) and total duration of therapy on the QFT-IT mitogen-induced response was evaluated. RESULTS: Agreement between TST and QFT-IT results was moderate (k=0.38). Frequency of QFT-IT indeterminate results was low (2.5%). In patients with risk factors for LTBI, the odds of a positive IFN-γ assay was increased by a factor of 27.6 (P=0.002), whereas there was no positive TST. There was a significant difference in the mitogen-induced IFN-γ secretion among various treatments (P=0.038). TNF-α inhibitors were associated with increased mitogen-induced IFN-γ secretion compared to monotherapy with conventional DMARDs (P=0.008). All children screened prior to anti-TNF-α treatment exhibited a negative QFT-IT and no active TB disease was detected during a 2-year follow-up. CONCLUSIONS: QFT-IT may be a more reliable test than TST for detection of LTBI in children with rheumatic diseases receiving anti-rheumatic treatment. Drug regimen might influence the mitogen-induced IFN-γ secretion and the effect of TNF-α inhibitors might vary according to the specific agent administered.

Health-related quality of life in juvenile-onset systemic lupus erythematosus and its relationship to disease activity and damage.

OBJECTIVE: To assess the health-related quality of life (HRQL) of patients with juvenile-onset systemic lupus erythematosus (JSLE) and its relationship with disease activity and accumulated damage. METHODS: In this cross-sectional study, HRQL was assessed using the Child Health Questionnaire (CHQ), disease activity using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), and accumulated damage using the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI). RESULTS: A total of 297 patients were included. The mean +/- SD physical and psychosocial summary scores of the CHQ were 40.2 +/- 15.0 and 44.8 +/- 10.7, respectively. The most impaired CHQ subscales were global health, general health perceptions, and parent impact-emotional. The SLEDAI score was significantly correlated with both the physical summary score (r = -0.29, P < 0.0001) and psychosocial summary score (r = -0.25, P < 0.0001), whereas the SDI score was significantly correlated only with the physical summary score (r = -0.23, P = 0.0001). CONCLUSION: We found that patients with JSLE have significant impairment of their HRQL, particularly in the physical domain. HRQL may be affected by both disease activity and accumulated damage, particularly in the renal, central nervous, and musculoskeletal systems.