Disease activity measures have been only recently developed in pediatrics. The DAS was developed in 1993 as a measure to assess adult rheumatoid arthritis (RA) [17]. The DAS is a composite score that has four components: The swollen joint count of 44 joints, the Richie articular index that grades the joint tenderness on a scale of 0–3, the ESR, and the patient assessment of general health between 0 and 10. The calculation for the DAS and its modifications can be done online at http://​www.​das-score.​nl/​www.​das-score.​nl/​dasculators.​html.This score, its modified version the DAS28, and the DAS-based European League Against Rheumatism (EULAR) response criteria are well-known measures of disease activity in RA. For daily practice, it has been shown that a tight control strategy, including measurement of disease activity using the DAS and planned adjustment of antirheumatic medication, is an effective strategy for RA [18]. The DAS 28 is a popular tool both for day-to-day clinical care and for trials as well. Here, the four variables are 28-joint count for swollen and tender joints, the ESR, and the patient global health assessment. Simple calculators give a numeric score to each patient with scores < 2.6 equaling remission [19].

The JADAS has been developed and published in 2009. The score was developed by 9 pediatric rheumatologists and the components of JADAS were taken from the core set criteria. The four components chosen were active joint count, MD global assessment (0–10), patient global assessment (0–10), and the ESR (normalized from 0 to 10 using the formula, ESR (mm/h) –20/10). The restricted joint count and the functional outcome were excluded as they include damaged joints. The active joint count was taken from a total of 27 joints: cervical spine, elbows, wrists, metacarpophalangeal joints (1, 2, and three), proximal interphalangeal joints, hips, knees, and ankles. Two other versions with a 10 joint reduced count and a 71 joint count were also evaluated. The total score is arrived at by a simple numeric score: 0–57 for the JADAS 27. This score was validated on more than 4500 patients. The study is robust enough to be used on all categories of JIA. The main drawbacks are that the ocular disease component has not been evaluated and that the extra-articular features for SJIA are not fully captured [20]. A comparative Table 13.2 lists the domains for the core set and JADAS. It has been recently shown that not only is the JADAS a good measure of disease activity at a point but also that its change over time is more sensitive than the ACRpedi30 in defining patients who improve [21]. In addition, values for remission, minimal disease activity, and acceptable symptoms have been defined for JADAS [22]. This tool can be easily used in the clinic as it is an indicator of absolute disease activity [11].

Disease activity measures for juvenile spondyloarthropathy (JSpA): The JADAS tool during development assessed very few children with JSpA (<1 %) [21]. Specific disease features of JSpA such as enthesitis and spinal inflammation are not captured in JADAS, and conversely disease activity measures for adult spondyloarthropathies such as BASDAI (Bath ankylosing disease activity index) are heavily weighted toward spinal inflammation [23]. The latter is not a very prominent feature early on in children with JSpA. Thus, the juvenile spondyloarthritis (JSpA) disease activity (JSpADA) index was developed in 2014. This measure assesses eight disease features and includes active joint count, active enthesitis count, morning stiffness, clinical sacroiliac disease, uveitis, and back mobility. It was assessed on a retrospective cohort of 178 children with JSpA and was shown to be an effective tool for disease assessment [24].

The Juvenile Arthritis Multidimensional Assessment Report (JAMAR) includes 15 parent or patient-centered items that assess well-being, pain, functional status, health-related quality of life, morning stiffness, disease activity, disease status and course, joint disease, extra-articular symptoms, side effects of medications, therapeutic compliance, and satisfaction with illness outcome. This was designed in 2011 and was proven to have content and face validity. This is therefore a parent-/patient-reported outcome (PRO) that encompasses several domains in one instrument [25]. The JAMAR should be filled by both parent and child as they may have different perceptions especially with active disease [26]. It is important for the pediatric rheumatologist to take into consideration the PRO to help make the right therapeutic choice for the child. The other composite indices for JIA evaluation are Juvenile Arthritis Parent Assessment Index (JAPAI) and the Juvenile Arthritis Child Assessment Index (JACAI).

The economic impact of JIA has been studied, predominantly from the USA and Europe. Mean annualized direct cost per child with JIA in a study of 70 children from the USA published in 1992, in the pre-biologic era, was $ 7,905 (Indian Rupees: 3.6 lakhs). The family cost including absenteeism from work was 1524$ per year [48]. Another recent study, published from Germany, studied the mean cost of JIA patient care per year in 2009. This was 4663 Euro (INR 2.9 lakhs) [49]. This clearly reflects the difference in costs of health-care delivery across the world as the latter data is 17 years later, has included the costs of biologics, and yet is lower than that published from the USA. The cost in the UK has been estimated to be lowest with a mean of 1649 pounds (INR: 1.12 lakhs). The highest cost here was for consultation with a pediatric rheumatologist [50].

There is a huge concern about the cost of biologics in the treatment of JIA. A Finnish study has estimated that after combining etanercept with the nonbiologic standard treatment, the total costs of refractory JIA calculated per year were only slightly higher than those of traditional therapy. This finding must be evaluated in light of the reduced inflammatory activity of the joint disease and the probable reduction of lifetime pain and disability produced by the disease [51].

As SLE is a multisystem disease, a composite measure is needed to capture information about multiple organ systems. SLE disease course is characterized by relapses and remissions. Due to this patients develop organ damage. It is critical and challenging to differentiate between disease activity and damage. For example, in a patient with lupus nephritis, new onset proteinuria could be due to relapse of disease or damage. In one scenario we need to increase immunosuppression and in another reduce it. Further SLE also impacts physical and social health and to measure QOL generic tools like CHAQ and CHQ are used though a child-friendly, simple tool called SMILEY has recently been developed.