Validity of Administrative Databases in Comparison to Medical Charts for Breast Cancer Treatment Data

Table 1

Characteristics of eligible women diagnosed with invasive breast cancer through Ontario Breast Screening Program between January 1, 2006, and December 31, 2009, by women with complete radiotherapy, chemotherapy, and surgery data.

Characteristics	Radiotherapy; N = 2,375; n (%)	Chemotherapy; N = 2,292; n (%)	Surgery; N = 2,400; n (%)
Age at diagnosis (years)
50–59	824 (34.7)	792 (34.6)	832 (34.7)
60–69	1,551 (65.3)	1,500 (65.4)	1,568 (65.3)
Year of diagnosis
2006	454 (19.1)	439 (19.2)	459 (19.1)
2007	597 (25.1)	574 (25.0)	602 (25.1)
2008	613 (25.8)	593 (25.9)	618 (25.8)
2009	711 (29.9)	686 (29.9)	721 (30.0)
Income quintile
1: lowest	417 (17.6)	400 (17.5)	423 (17.7)
2	466 (19.7)	447 (19.6)	471 (19.7)
3	474 (20.1)	456 (20.0)	478 (20.0)
4	447 (18.9)	432 (18.9)	452 (18.9)
5: highest	559 (23.7)	547 (24.0)	564 (23.6)
Missing	12	10	12
Community status
Urban	1,962 (82.7)	1,893 (82.6)	1,985 (82.8)
Rural	132 (5.6)	129 (5.6)	133 (5.5)
Rural remote	188 (7.9)	182 (7.9)	189 (7.9)
Rural very remote	91 (3.8)	87 (3.8)	91 (3.8)
Missing	2	1	2
Comorbidity
No	1,338 (57.2)	1,290 (57.2)	1,354 (57.3)
Yes	1,001 (42.8)	967 (42.8)	1,008 (42.7)
Missing	36	35	38
Breast cancer classification
Invasive	698 (30.2)	675 (30.2)	703 (30.1)
Invasive + DCIS	1,615 (69.8)	1,559 (69.8)	1,635 (69.9)
Missing	62	58	62
TNM stage
I	1,544 (65.9)	1,507 (66.7)	1,555 (65.7)
II	675 (28.8)	637 (28.2)	683 (28.9)
III	123 (5.3)	117 (5.2)	128 (5.4)
Missing	33	31	34
Histologic grade
1	706 (30.4)	694 (30.9)	711 (30.3)
2	1,103 (47.5)	1,060 (47.2)	1,117 (47.6)
3	514 (22.1)	491 (21.9)	520 (22.1)
Missing	52	47	52
Triple negative
No	2,093 (90.6)	2,034 (91.0)	2,112 (90.6)
Yes	217 (9.4)	202 (9.0)	220 (9.4)
Missing	65	56	68
Treatment centre region
South Central	1,213 (51.1)	1,155 (50.4)	1,230 (51.3)
South Eastern	411 (17.3)	403 (17.6)	412 (17.2)
South Western	463 (19.5)	453 (19.8)	468 (19.5)
Northern	288 (12.1)	281 (12.3)	290 (12.1)

DCIS, ductal carcinoma in situ.