Statistical Analysis:
Descriptive statistics were used to summarize patient, tumor and
treatment characteristics as well as outcomes. A summary marginalization
score combined scores from the three marginalization domains considered
in this analysis (material deprivation, residential instability and
ethnic concentration). Patients were stratified by marginalization
quintiles and their characteristics were compared using the chi-square
test for categorical and ordinal data or Wilcoxon rank sum test for
continuous data.
The primary outcome was defined as overall survival from the date of
endometrial cancer diagnosis to the date of death, as recorded in the
Registered Persons Database. Survival was estimated using the
Kaplan-Meier method and compared across groups using the log-rank test.
Cox regression methods were used to assess factors associated with
survival in the study population after verification of the proportional
hazards assumption. Variables incorporated in the analyses included
patient factors, such as age, comorbidity score, obesity, income and
rurality, as well as marginalization indices; and disease factors, such
as histology, stage, and previous history of cancer. Confidence
intervals were constructed for statistics of interest. All tests and
confidence intervals were two-sided and defined at the α=0.05 level of
significance. All analyses were performed using SAS version 9.2 (SAS
Institute, Cary, NC) and R (www.r-project.org).