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Methodology 7.1.d

Breast Cancer Screening Quality and Efficiency Methodology
Short description of Indicator Percentage of women screened within 90 days of confirmation of high risk status, by Local Health Integration Network (LHIN), 2013 to 2016.
Rationale for measurement

The High Risk Ontario Breast Screening Program (High Risk OBSP) was launched in 2011 as an extension of the OBSP1,3, following guidelines from the Ontario Health Technology Advisory Committee (OHTAC) that women at high risk for breast cancer be screened in a programmatic setting to ensure appropriate quality assurance processes are in place.2

An evaluation of the first year of the High Risk OBSP high risk screening program found that of the 35 cancers detected in the first year of the program, none were detected by mammogram alone, 23 were detected by MRI alone, and the positive predictive value (the proportion of women with positive screens who were subsequently diagnosed with cancer) was highest for detection based on MRI and mammogram.3,4 The invasive cancer detection rate was 16.3 per 1,000, three times that for average risk women.3

A meta-analysis of studies evaluating MRI compared to mammography in women at high risk for breast cancer found that MRI has a higher sensitivity and specificity (ability to determine true breast cancer status) than mammogram for women at high risk.5 Therefore, Cancer Care Ontario recommends screening with MRI in addition to digital mammography for women determined to be at high risk for breast cancer.6

Evidence/references for rationale
  1. Ministry of Health and Long-Term Care. Expansion of the Ontario Breast Screening Program (OBSP) to Include Women Aged 30 to 69 at High Risk for Breast Cancer [Internet]. Toronto: INFOBulletin; 2011 [cited 2017 Nov 29]. Available from: http://www.health.gov.on.ca/en/pro/programs/ohip/bulletins/10000/bul10016.pdf
  2. Health Quality Ontario. Cancer Screening with Digital Mammography for Women at Average Risk for Breast Cancer, Magnetic Resonance Imaging (MRI) for Women at High Risk: An Evidence-Based Analysis. Ontario Health Technology Assessment Series. 2010;10(3):1-55.
  3. Chiarelli AM, Prummel MV, Muradali D, Maipruz V, Horgan M, Carroll JC et al. Effectiveness of screening with annual magnetic resonance imaging and mammography: results of the initial screen from the Ontario high risk breast screening program. J Clin Oncol. 2014 Jul 20;32(1):2224–30.
  4. Cancer Care Ontario. Ontario breast screening 2011 program report. Toronto ON): Cancer Care Ontario; 2013.
  5. Warner E, Messersmith H, Causer P, Eisen A, Shumak R, Plewes D. Systematic review: Using magnetic resonance imaging to screen women at high risk for breast cancer. Ann Intern Med. 2008 May 6;148(9):671–9.
  6. Warner E, Messersmith H, Causer P, Eisen A, Shumak R, Plewes D. Magnetic resonance imaging screening of women at high risk for breast cancer. Toronto (ON): Program in Evidence-Based Care (PEBC), Cancer Care Ontario; 2012 Aug.
Calculations for the indicator (Total number of Ontario women, age 30 to 69, who were screened with MRI or Ultrasound within 90 days of confirmation of high risk status / Total number of women, age 30 to 69, confirmed to at high risk) x100 = High Risk Screen Wait Time
Standardized Rate Calculation N/A
Unit Percentage (%)
Data sources
  • ​ICMS (Integrated Client Management System) - OBSP genetic assessment, high risk confirmation and high risk screens
  • PCCF+, version 6D - Residence and socio-demographic information
Time Frame 2013 - 2016
Geographic Scale
  • ​Provincial
  • LHIN of residence
Denominator description Total number of Ontario women, age 30 to 69, confirmed to be at high risk
  • Women, age 30 to 69, confirmed high risk
  • Age is based on the OBSP high risk confirmation date
  • Confirmation date of high risk status for women referred by a physician (Category A) is defined as the most recent of either the referral date or the update date. For women referred to genetic assessment (Category B), it is defined as the most recent of either the genetic assessment date or the update date. Update date is selected only if it is before the OBSP high risk screening episode date.
  • Women with a valid date per below criteria were included:
    • Women with an OBSP registration date (date the high risk referral information was entered)
    • Women with an initial primary care provider visit date
    • Women with a confirmation date
  • LHIN assignment was determined using PCCF+, version 6D; residential postal code was used to identify LHIN

Exclusions:

  • Women with a missing or invalid HIN, date of birth, postal code or LHIN
  • Women who declined to participate in high risk OBSP screening, or have no screens.
  • Women with negative duration (confirmation date after screen date)
  • Women with a positive duration but interval greater than 365 days
Numerator description Total number of Ontario women, age 30 to 69, screened with an OBSP MRI or Ultrasound within 90 days of confirmation of high risk status
  • Women, age 30 to 69, confirmed high risk and screened with an OBSP MRI or Ultrasound within 90 days of confirmation of high risk status date
Considerations 
  • This indicator is only reported for women’s first OBSP MRI or Ultrasound screen after confirmation date.
  • Women referred by a physician (Category A) after July 1, 2011 may have had both either MRI or Ultrasound prior to their registration in the high risk program and are not due to be re-screened until one year after their previous screening date.
  • Women can be referred to genetic assessment at age 29, but cannot be screened in the OBSP high risk program until age 30 (or 10 weeks short of their 30th birthday).
  • If the same women was referred twice to the OBSP high risk program within a year, the latest registration date is used
Data availability & limitations
  • Data are available from July 2011
  • There is a four-month reporting lag for this indicator. Up to three months are required to allow follow-up of women for the screening to occur after confirmation of high risk status. Another month is required for the data entry of the screening result
CSQI Year 2018