2.1 | Study design, population, and data resources
After obtaining Research Ethics Board approval from the Hospital for
Sick Children and Sunnybrook Health Sciences Centre, we carried out a
population-based retrospective cohort study using the IMPACT Cohort. The
need for individual consent was waived.
The creation of the cohort has
been described in detal previously.5 It comprises all
Ontario residents, aged 15 to 21 years at diagnosis of one of six common
cancers (including bone tumors) treated at an adult center (a Regional
Cancer Center or a community hospital) or a pediatric center (one of the
five specialized, tertiary care centers) from 1992 to
2012.5 In Ontario, AYA aged less than 18 may receive
care at either pediatric or adult centers, whereas older AYA (≥18)
almost always are treated in adult centers.7,9 IMPACT
was built using two data sources. The Pediatric Oncology Group of
Ontario Networked Information System (POGONIS) database captures
demographic, disease- and treatment-related data of children diagnosed
with cancer before the age of 18 who received their care at a pediatric
center.22,23 AYA diagnosed between ages 15 to 21 who
received their cancer care at an adult center were identified through
the Ontario Cancer Registry (OCR) and their clinical data collected by
trained chart abstractors.5,7 These data were combined
to form the IMPACT database. All AYA patients diagnosed with OGS or EWS,
except those who lived or were diagnosed out of the province (Ontario),
were included in this study. The IMPACT database was linked
deterministically using encrypted personal identifiers to
population-based health services databases (CIHI-DAD for hospitalization
records, NACRS for emergency room visits, OHIP for outpatients visits
and physician’s billing information; see Appendix 1 ) hosted at
ICES (formerly, the Institute for Clinical Evaluative Sciences).