Patients and Study Design
We performed a retrospective review of presenting features and outcomes of all children aged between 1 day and <18 years who were diagnosed with acute leukaemia between January 1st 2009 and December 31st 2018 at the Women’s and Children’s Hospital (WCH) in SA, and Perth Children’s Hospital (PCH) in WA. The WCH and PCH are the sole referral sites for children with cancer for their states, with WCH also serving as the primary referral centre for children with suspected malignancies from the NT.
Cases were ascertained from hospital-based registries at WCH and PCH. Demographic characteristics, Indigenous status (self-reported) and diagnostic features at presentation, including full blood count, biochemistry, peripheral blast count, blast immunophenotype, blast genotype, molecular studies, central nervous system status, final risk stratification, treatment regimen and outcome were collected from medical records. The World Health Organisation classification of myeloid neoplasms and acute leukaemia was used for classification into diagnostic categories10. Final risk stratification was according to the co-operative group treatment protocols used in the respective centres, i.e. primarily the Children’s Oncology Group for WA and the Berlin-Frankfurt-Munster protocols for SA/NT.
Residential address at diagnosis was categorised, first, by geographic remoteness using the Australian Statistical Geography Standard Remoteness Index (‘remote/very remote’, ‘outer regional,’ ‘inner regional’ or ‘major city’)11 and, second, by area-based socioeconomic status (SES) using the Index of Relative Socio-economic Disadvantage (‘least disadvantaged’ (quintile 5 scores), ‘middle SES’ (quintiles 2 to 4) and ‘most disadvantaged’ (quintile 1)12. The latter (referred to as Socio-economic Index) is derived from national census data and incorporates income, educational attainment, employment and type of occupation.