Background Mortality rates in children with juvenile idiopathic arthritis (JIA) are increased compared to the general population. Systemic arthritis, a more severe subtype of JIA, is expected to be linked to an increase in mortality compared to other subtypes although evidence is so far lacking.
Objectives To calculate the standardised mortality rates (SMR) in children with severe JIA, defined as requiring biologic therapy.
Methods The study population comprised JIA subjects recruited to the BSPAR Etanercept Cohort Study. Deaths were identified through follow-up via hospital questionnaires and links to the national death register. All patients were followed from registration until death, last follow-up, or 31/12/2012, whichever came first. Poisson regression calculated crude incidence rates per 1,000 person years (pyears). SMRs were calculated using age- and gender-specific mortality rates in the UK population.
Results 693 patients were registered and followed over 4475 pyears (mean age 11 years, median disease duration at registration 4 years, mean follow-up per patient 6.4 years). Seven deaths were reported, with an expected rate of 0.96. Four of the deaths occurred in systemic JIA patients. The incidence rate was 1.6/1,000 pyears with an SMR of 7.3 (95% CI) 2.9, 15.0). Patients with systemic JIA had an SMR of 21.7 (95% CI 5.9, 55.4) with non-systemic SMR of 3.9 (0.8, 11.3) (Table 1) Causes of death included macrophage activation syndrome, sepsis, and 2 in association with stem-cell transplants.
Conclusions In a select group of patients with severe JIA, there appears to be a high mortality rate, particularly among severe systemic JIA, compared to a healthy paediatric population. Whilst death is still a rare outcome, this study highlights the importance of the diagnosis of JIA.
Disclosure of Interest None declared