Mortality Rates in Children, Young People, and Young Adults with JIA: an observational study using the Clinical Practice Research Datalink (CPRD)

Objective: Many rheumatological conditions have increased mortality rates, however, there is conflicting evidence regarding the impact of JIA on mortality. This analysis aimed to calculate the all-cause mortality rate of patients with JIA, compared with (a)matched-control patients, and (b)the general population mortality estimates.

Methods: Using the UK General Practice data CPRD, JIA cases starting <16 years old from England were included, matched 4-to-1 with non-JIA controls (birth year, gender, practice). Exposure started on first JIA-code date (matched-date for controls) or 1-Jan-2000, whichever was latest. Follow-up continued until 31-Dec-2018 or death, whichever was first. Cox-proportional hazards models compared mortality in JIA versus matched-controls. JIA rates were stratified by systemic versus non-systemic JIA. Standardised mortality rates (SMRs) were generated for JIA versus general population estimates (calendar year, age, gender).

Results: There were 4762 patients with JIA (30 deaths) and 13957 matched-controls (27 deaths); patient demographics were similar between cohorts. Mortality rate for JIA was 6.2/10000 person years (95%CI:4.3-8.9), and 1.9/10000 person years (95%CI:1.3-2.8) for matched-controls; JIA patients had 3.3 times higher mortality (95%CI:2.0-5.5). Patients with systemic JIA had 3.3 times higher mortality (95%CI:1.6-6.9) versus those with non-systemic JIA. The SMR for JIA was 2.9 (95%CI:2.1-4.2). Eighteen (60%) JIA deaths occurred before 2012.

Conclusions: This analysis calculated mortality rates in young people with JIA in England. Death in young people with JIA is exceedingly rare. Higher rates were observed in patients with systemic JIA. Over half the deaths occurred prior to 2012 when biologic treatment, particularly for systemic JIA, was limited.