education, poverty, and incomeweighted equally,with 1 being the lowest
value. To assess the prevalence of comorbidmedical diseases,we used the
Klabunde adaptation of the Charlson comorbidity index (i.e., the
Klabunde–Charlson index) [17,18]. Medicare inpatient and outpatient
claims were searched for diagnostic codes of the International Classification
of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) [19].
Area of residence was categorized as metropolitan or nonmetropolitan
and tumor grade was grouped as well, moderately, or poorly differentiated
or unknown. Tumor histology was classified as serous, mucinous,
endometrioid, clear cell or other. Stage was captured using the
American Joint Cancer Commission staging criteria.