Technical Information

Age-adjusted percentage of Ontario screen-eligible women, 50-74 years old, who completed at least one mammogram within a 30-month period

Figures 2-4

There is strong evidence from clinical trials that breast cancer screening can reduce breast cancer mortality. (1) Observational evidence indicates that widespread adoption of mammography screening has contributed to a decline in mortality from breast cancer. (1) Adequate participation in breast cancer screening is essential for reductions in mortality to occur in the Ontario population. (2–4)

1. Nelson H, Fu R, Cantor A, Pappas M, Daeges M, Humphrey L. Effectiveness of breast cancer screening: Systematic review and meta-analysis to update the 2009 U.S. Preventive Services Task Force Recommendation. Ann Intern Med. 2016 Jan 12. doi: 10.7326/M15-0969. [Epub ahead of print].
2. Canadian Partnership Against Cancer. Breast cancer screening in Canada: Monitoring and evaluation of quality indicators- results report, December 2009-January 2010. Toronto (ON): Canadian Partnership Against Cancer; 2017.
3. Canadian Partnership Against Cancer. Report from the evaluation indicators working group: Guidelines for monitoring breast cancer screening program performance (3rd edition). Toronto: Canadian Partnership Against Cancer; 2013 Feb.
4. Coldman A, Phillips N, Wilson C, Decker K, Chiarelli A, Brisson J et al. Pan-Canadian study of mammography screening and mortality from breast cancer. J Natl Cancer Inst. 2014 Oct 1;106(8): pii: dju261. Erratum in: J Natl Cancer Inst. 2015 Jan;107(1):dju404.

(Total number of Ontario screen-eligible women, 50-74 years old, who have completed at least one mammogram in a given 30-month period/ Total number of Ontario screen-eligible women, 50-74 years old in the reporting period) x 100 = Mammogram participation

2011 Canadian population

Percentage (%)

• ICMS (Integrated Client Management System) - OBSP mammograms
• OHIP CHDB (Claims History Database) - Non-OBSP mammogram and mastectomy claims
• OCR (Ontario Cancer Registry) - Invasive and in-situ breast cancers
• RPDB (Registered Persons Database) – Demographics
• PCCF+, version 6C - Residence and socio-demographic information 

2006-2015

• Provincial (Ontario)
• LHIN of residence

Total number of Ontario screen-eligible women, 50-74 years old, in the reporting period

• Ontario screen-eligible women aged 50-74 at the index date
• Index date was defined as the midpoint in the reporting period, e.g. Jan 1st 2012 for 2011-2012
• The 2011 Canadian population was used as the standard population for calculating age-standardized rates 
• LHIN assignment was determined using PCCF+, version 6C; residential postal code was used to identify LHIN 
• Public health unit data was determined using PCCF+, version 6C

Exclusions:

• Women with a missing or invalid HIN, date of birth, postal code or LHIN
• Women with a prior diagnosis of invasive or in-situ breast cancer before Jan 1st of the reporting period; prior diagnosis of breast cancer was defined as: ICD-O-3 codes: C50, a morphology indicative of breast invasive or in-situ cancer, microscopically confirmed with a path report

Women with a mastectomy before Jan 1^st of the reporting period. Mastectomy was defined in OHIP by fee codes E505, E506, E546, R108, R109, and R117

Total number of Ontario screen-eligible women, 50-74 years old, who have completed at least one mammogram in a given 30-month period

• Identifying mammograms:
  • OBSP mammograms for screening purposes were identified in the Integrated Client Management System (ICMS)
  • Non-OBSP mammograms were identified using fee codes in OHIP:
    • X178 (screening bilateral mammogram)
    • X185 (diagnostic bilateral mammogram)
• All mammograms in ICMS were counted, including those with partial views

Each woman was counted once regardless of the number of mammograms performed in a 30-month period; if a woman had both a program and non-program mammogram within a 30-month period, the program status was selected

A small proportion of mammograms performed outside of OBSP as diagnostic tests could not be excluded from the analysis

• Historical RPDB address information is incomplete; therefore, the most recent primary address was selected for reporting, even for historical study periods
• CHDB code X178 for screening bilateral mammography was introduced in October 2010
  • CHDB code X185 was used for both screening and diagnostic mammography prior to October 2010; since October 2010, X185 has been used for diagnostic mammography only; however, some screening mammograms after October 2010 may still use X185 for claims

Percentage of Ontario screen-eligible women, 50-72 years old, who had a subsequent OBSP screening mammogram within 30 months of a previous program mammogram

Figures 5 and 6

In order to realize the full benefit of an organized breast screening program in the reduction of breast cancer mortality, it is important to ensure that women return for regular screening at the recommended interval. (1-4)

The Canadian Task Force on Preventive Health Care recommends that women aged 50-74 who are at average risk for breast cancer are screened every 2–3 years. (5) Cancer Care Ontario recommends that women ages 50–74 who are at average risk for breast cancer receive a screening mammogram every 2 years. (2) Although the recommendation is 24 months, it may take up to 30 months for women to be re-screened. (2–4) There is no evidence to indicate that the benefits of screening are lost if screening occurs up to six months after the recommended interval. (6)

1. Nelson H, Fu R, Cantor A, Pappas M, Daeges M, Humphrey L. Effectiveness of breast cancer screening: Systematic review and meta-analysis to update the 2009 U.S. Preventive Services Task Force Recommendation. Ann Intern Med. 2016 Jan 12. doi: 10.7326/M15-0969. [Epub ahead of print].
2. Cancer Care Ontario. Ontario Breast Screening Program 2011 report. Toronto, Ontario: Cancer Care Ontario; 2013.
3. Canadian Partnership Against Cancer. Report from the evaluation indicators working group: Guidelines for monitoring breast cancer screening program performance (3rd edition). Toronto: Canadian Partnership Against Cancer; 2013 Feb.
4. Canadian Partnership Against Cancer. Breast cancer screening in Canada: Monitoring and evaluation of quality indicators- results report, January 2011–December 2012. Toronto (ON): Canadian Partnership Against Cancer; 2017.
5. The Canadian Task Force on Preventive Health Care. Recommendations on screening for breast cancer in average-risk women aged 40-74 years. CMAJ. 2011; 183(17):1991-2001.
6. Chen Y, Brock G, Wu D. Estimating key parameters in periodic breast cancer screening - application to the Canadian national breast screening study data. Cancer Epidemiology 2010; 34(4):429-33.

(Total number of Ontario screen-eligible women, 50-72 years old, who had a subsequent OBSP screening mammogram within 30 months of a previous program mammogram/ Total number of Ontario screen-eligible women, 50-72 years old, with a program mammogram in a given year) x 100 = Retention

​N/A

Percentage (%)

• ICMS (Integrated Client Management System) - OBSP mammograms, demographics, address at time of screening and date of death
• OHIP CHDB (Claims History Database) - Mastectomy claims
• OCR (Ontario Cancer Registry) - Invasive and in-situ breast cancers
• PCCF+, version 6C - Residence and socio-demographic information 

​2009-2013

• Provincial (Ontario)
• LHIN of residence

• Total number of Ontario screen-eligible women, 50-72 years old, with a program mammogram in a given year
• Average risk women, aged 50-72 at the index date, who had an OBSP screening mammogram in a given year
• Index date was defined as the first OBSP screen date per person in ICMS in a given year
• Mammograms were identified by OBSP mammogram records in ICMS for screening purposes
• Each woman was counted once regardless of the number of mammograms performed
• All mammograms were counted, including those with partial views
• LHIN assignment was determined using PCCF+, version 6C; residential postal code was used to identify LHIN.
• Public health unit data was determined using PCCF+, version 6C

Exclusions:

• Women with a missing or invalid HIN, date of birth, postal code or LHIN
• Women with a prior diagnosis of invasive or in-situ breast cancer before the index date; prior diagnosis of breast cancer was defined as: ICD-O-3 codes: C50, a morphology indicative of breast invasive or in-situ cancer, microscopically confirmed with a path report from OCR or screen-detected breast cancer from ICMS
• Women with a mastectomy before the index date; mastectomy was defined in OHIP by fee codes E505, E506, E546, R108, R109, and R117
• Women who died, had breast cancer or mastectomy in the 30-month retention period and were not re-screened
• Women who were re-screened during the 30-month retention period but who had a mastectomy or breast cancer diagnosis after the index date but before the re-screen date

Total number of Ontario screen-eligible women, 50-72 years old, who had a subsequent program mammogram within 30 months of a previous program screening mammogram in a given year

• Subsequent screening mammograms were identified through ICMS
• All tests were considered, regardless of test result

Women who have moved out of the province could not be excluded

• This indicator includes OBSP mammograms only
• There is a 31-month reporting lag for this indicator, as one complete month is required to allow for the data entry of the screening result and 30 months is required to follow up clients to determine the next screen date