You are using an outdated browser. We suggest you update your browser for a better experience. Click here for update.
Close this notification.
Skip to main content Skip to search

Methodology 7.1.b

Breast Cancer Screening Quality and Efficiency Methodology
Short description of Indicator Percentage of Ontario screen-eligible women age 50 to 72 screened in the Ontario Breast Screening Program (OBSP) with a biennial recall recommendation who had a subsequent program mammogram within 18 months of the previous mammogram
Rationale for measurement

Early return rate is an indicator of breast cancer screening participation behaviour that falls outside of the recommended guidelines for screening frequency. Optimal benefits of screening are achieved by regular participation in the screening program.1

Annual screen rates should be monitored to understand the impact of annual screening on cancer detection rates, abnormal screen rates, and program capacity, and to ensure comparability of results across Canada.2

Evidence/references for rationale
  1. 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; February, 2013.
  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; 2015.
Calculations for the indicator (Total number of Ontario screen-eligible women, age 50 to 72, with a biennial OBSP screening recall recommendation who had a subsequent program mammogram within 18 months of a previous program screening mammogram / Total number of Ontario screen-eligible women, age 50 to 72, with a biennial OBSP screening recall recommendation in a given calendar year) x 100 = Early Return
Standardized Rate Calculation N/A
Unit Percentage (%)
Data sources
  • ​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
  • RPDB (Registered Persons Database) – Demographics
  • PCCF+, version 6D - Residence and socio-demographic information
Time Frame 2012-2015
Geographic Scale
  • ​Provincial (Ontario)
  • LHIN of residence
  • Public Health Unit (PHU)
Denominator description Total number of Ontario screen-eligible women, age 50 to 72, with a biennial OBSP screening recall recommendation in a given year
  • Average risk women, aged 50-72 at the index date, who had an OBSP mammogram with a biennial screening recall recommendation in a given year
  • Index date was defined as the first OBSP screen date per person in ICMS in a given year with a biennial screening recall recommendation
  • Mammograms were identified by OBSP mammogram records in the 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 6D; residential postal code was used to identify LHIN
  • Public health unit data was determined using PCCF+, version 6D; residential postal code was used to identify public health unit

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 18-month follow-up period and were not re-screened
  • Women who were re-screened during the 18-month follow-up period but who had a mastectomy or breast cancer diagnosis between the index screen date and re-screen date
Numerator description Total number of Ontario screen-eligible women, age 50 to 72, with a biennial OBSP screening recall recommendation who had a subsequent program mammogram within 18 months of a previous program screening mammogram
  • Subsequent screening mammograms were identified through ICMS
  • All subsequent screening mammograms were considered, regardless of test result
Considerations  Women who have moved out of the province could not be excluded
Data availability & limitations
  • This indicator includes OBSP mammograms only
  • There is a 19-month reporting lag for this indicator, as one complete month is required to allow for the data entry of the screening result and 18 months is required to follow up clients to determine the next screen date
  • Women in the OBSP may only return 11 months or later from her previous program screen (earlier return dates are not permitted in the program)
CSQI Year 2018