Introduction 1 2 3 1 The aim of the present study was therefore to compare the measurement properties of the JAFAS and the CHAQ in an unselected population of children with JIA on the level of individual items. Materials and methods Study design and patient recruitment 4 Assessment methods The JAFAS (range 0–20) was developed as an objective measure of functional ability in children with rheumatic diseases between 7 and 18 years. With the JAFAS, the observed time needed to perform ten activities is compared with a standard ‘criterion’ time. The JAFAS was administered by one well-trained paediatric physical therapist (Bekkering). The CHAQ, including 30 activities in eight different domains, with a total score ranging from 0 (no limitation) to 3 (maximal limitation), was completed by interviewing the children. 5 6 Statistical analysis r s κ 7 α 8 Results Characteristics of the patients From the 33 eligible children who visited the outpatient paediatric rheumatology clinic in the study period, two children refused to participate, and three did not fulfil the inclusion criteria (two children had serious mental retardation and one child had the attention deficit hyperactivity disorder). Thus, 28 children, 12 boys and 16 girls, were included. Their median age was 10.0 years (range 7.3–12.8), and the median disease duration was 3.3 years (range 0.1–10.2). A majority of the children had a polyarticular (nine patients) or oligoarticular pattern (11 patients) of joint involvement. Systemic onset JIA (three patients), arthritis and psoriasis (four patients) and enthesitis type JIA (one patient) were less frequently seen. Twenty (71%) children used anti-rheumatic medication, of whom 17 (68%) used disease-modifying anti-rheumatic drugs and three (11%) used oral corticosteroids. The median scores of the ESR (7.7 mm/h, range 2–54), the JC-swollen (1.0, range 0–28), the JC-tender (0.8, range 0–8), the VAS-well-being (0.2, range 0–2.5), VAS-pain (0.1, range 0–1.5) and VAS-paediatrician (0.2, range 0–2.7) point at a relatively low level of disease activity. With respect to joint ROM, the median JC-limitation score was 1.0 (range 0–17), and the median EPM-ROM score was 0. 5 (range 0–19.5). 1 Fig. 1 Frequencies of JAFAS and CHAQ scores. No disability JAFAS = 0, CHAQ = 0. Mild disability JAFAS = 1–3, CHAQ = 0–0.5. Moderate disability JAFAS = 4–9, CHAQ = 0.6–1.5. Severe disability JAFAS = 10–20, CHAQ = 1.6–3.0  Reliability and validity α p r p r p 7 κ 1 Table 1 JAFAS and CHAQ scores and their associations (Spearman correlation coefficients) in 28 patients with JIA Item JAFAS Number of patients limited in activity Internal reliability, item–total correlation CHAQ Number of patients limited in activity Internal reliability, item–total correlation Concordance among JAFAS and CHAQ items Number of concordant pairs b κ 1 Button shirt/blouse 9 0.85** Dress, including tying shoelaces and doing buttons 7 0.76** 20 3/5 0.30 ns 2 Pull shirt or sweater over head 1 0.38* Pull on sweater over head 1 0.34 ns 28 0/0 1.00** 3 Pull on both socks 2 0.49** Pull on socks 7 0.64** 21 6/1 0.13 ns 4 Cut food with knife and fork 4 0.70** Cutting meat 7 0.79** 21 5/2 0.23 ns 5 Get into bed 0 0.00 Getting in and out of bed 3 0.47* 24 4/0 a 6 Get out of bed 0 0.00    24 4/0 a 7 Pick something up off floor from standing position 1 0.38* Bend down to pick up clothing or a piece of paper 5 0.62** 24 4/0 0.29* 8 From standing position sit on floor, then stand up 2 0.52** Stand up from a low chair or floor 2 0.51** 28 0/0 1.00** 9 Walk 50 feet without assistance 1 0.38* Walk outdoors on flat ground 5 0.67** 24 4/0 0.29* 10 Walk up flight of 5 steps 1 0.38* Climb up five steps 7 0.69** 22 6/0 0.20 ns Total scores   α   α r  10 JAFAS items 14 0.91 9 CHAQ items 18 0.92 0.56** total CHAQ score 18 0.96 0.55** p p a b Construct validity 2 Table 2 Spearman correlation coefficients between JAFAS, CHAQ and other measures in 28 patients   JAFAS CHAQ CHAQ (9 items) VAS-paediatrician 0.41* 0.56** 0.34 ns ESR 0.37 ns 0.62* 0.75** Joint count on swollen joints 0.47* 0.65** 0.48* Joint count on tender joints 0.07 ns 0.41* 0.09 ns Joint count on limited joints 0.44* 0.64** 0.59** Paediatric EPM-ROM 0.50** 0.73** 0.88** CHAQ–pain 0.38* 0.69** 0.55** CHAQ-well-being 0.20 ns 0.44* 0.48* p p Discussion 1 1 9 10 11 The children’s version of the CHAQ was originally designed and validated with the questionnaire self-administrated by the patients. In this study, the questions were read out and filled in by the investigator to ensure appropriate completion. Although it is likely that with this method, the same results are obtained as with self-administration, a possible influence on the final scoring cannot be totally ruled out. 12 13