Abstract
JIA affects approximately 1-2 in 2000 children and young people in the UK. Rheumatological conditions are known to impact mortality; however, there is conflicting evidence regarding mortality rate and impact in JIA. The aim of this study was to calculate the all-cause mortality rate of patients with JIA, compared with (a) matched-controls, and (b) general population estimates.
Using UK General Practice data, CPRD (Aurum+Gold), this analysis included both prevalent and incident JIA cases under the age of 16 years old. Non-JIA control patients were matched 4-to-1 based on year of birth, gender, and practice. Date of death was identified through CPRD, or NHS-linked data (including cause of death). Exposure started on first JIA code date (or matched-date for controls) or 1-Jan-2000, whichever was latest. Follow-up continued until cut-off date (31-Dec-2018), or death, whichever was first. Cox-proportional hazards model was used to compare mortality in JIA versus matched-controls. JIA rates were additionally stratified by systemic versus non-systemic JIA. Standardised mortality rates (SMRs) were generated for JIA compared with the ONS general population estimates, based on calendar year, year of age, and gender. All patients were from England, due to the requirement for linkage with NHS hospital data.
4983 children and young people with JIA, and 14604 matched-control patients, were identified (Table); patient characteristics were similar between the cohorts. Mortality rate for JIA patients was 6.3/10000 person years (95%CI:4.4-8.9), and 2.0/10000 person years (95%CI:1.4-2.8) for control patients; JIA patients had 3.2 times higher mortality (95%CI:1.9-5.2). Patients with systemic JIA had 2.9 times higher mortality (95%CI:1.3-6.2) versus patients with non-systemic JIA (crude rate 13.9/10000 versus 5.2/10000). The SMR for JIA was 2.9 (95%CI:2.1-4.1); JIA patients had 2.9 times higher mortality versus the general population. Fifteen (47%) JIA deaths occurred before 2010.
This analysis calculated mortality rates in young people with JIA in the UK and found that death in young people with JIA is exceedingly rare. Slightly higher rates were observed in patients with systemic JIA, with approximately one additional death for every 2500 years versus controls. Almost half the deaths occurred before 2010 when biologic treatment, particularly for systemic JIA, was limited.
L. Kearsley-Fleet: None. N. Shaw: None. J. Leslie: None. M. Johnson: None. L.R. Wedderburn: None. K.L. Hyrich: None. J.H. Humphreys: None.
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