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Methodology 3.1.a

Cervical Screening Quality and Efficiency Methodology
Short description of Indicator Percentage of Ontario screen-eligible women with an abnormal Pap test result, 21 to 69 years old, who were diagnosed with pre-cancer or invasive cervical cancer after a follow-up colposcopy or a surgical procedure involving the cervix.
Rationale for measurement The positive predictive value (PPV) of the Pap test evaluates the probability of an abnormal Pap test being truly cervical cancer. The PPV of the Pap test is influenced by the rate of abnormal Pap tests, cancer and pre-cancer detection rate, and availability and accuracy of cytology and histology information.1,2 This indicator may be referred to as "cytology-histology agreement."1,2

Greater PPV of a pap tests provide benefits such as an decreased in workload and costs, decreased anxiety for women while waiting to repeat testing, the decreased risk of a false-positive result and consequently of unnecessary biopsies.3 While the incidence rate of invasive cervical cancer in Canada is low, many women who are diagnosed with cervical cancer did not receive appropriate follow-up after an abnormal Pap test result.4 It is therefore important to evaluate this measure of Pap test performance so that women receive high-quality cancer prevention services.

When evaluating the PPV of the Pap test it is important to note that the Pap test was designed to detect pre-invasive lesions of the cervix. The PPV of the Pap test is reported here as two separate measures, one for pre-invasive and one for invasive cervical cancer.
Evidence/references for rationale
  1. Agency for Healthcare Research and Quality [Internet]. Rockville: U.S. Department of Health and Human Services. Cervical cancer screening: percentage of Pap tests with an HSIL+ result that have a histological confirmation of HSIL, carcinoma in situ, or invasive carcinoma within 12 months of the HSIL+ Pap test; 2016 May [cited 14 Dec 2016]. Available from: https://www.qualitymeasures.ahrq.gov/summaries/summary/50388/cervical-ca...
  2. Public Health Agency of Canada. Performance monitoring for cervical screening programs in Canada. Ottawa (ON): Public Health Agency of Canada; 2009. Available from: http://www.phac-aspc.gc.ca/cd-mc/cancer/pmccspc-srpdccuc/pdf/cervical-eng.pdf
  3. Paolo Giorgi Rossi PhD, Francesca Carozzi, Guido Collina MD, et al. “HPV Testing Is an Efficient Management Choice for Women With Inadequate Liquid-Based Cytology in Cervical Cancer Screening” Am J Clin Pathol. 2012 Jul;138(1):65-71.
  4. Canadian Cancer Society, Advisory Committee on Cancer Statistics. Canadian cancer statistics 2015. Toronto (ON): Canadian Cancer Society; 2015. Available from: https://www.cancer.ca/~/media/cancer.ca/CW/cancer%20information/cancer%20101/Canadian%20cancer%20statistics/Canadian-Cancer-Statistics-2015-EN.pdf
Calculations for the indicator ( Total number of women, 21-69 years old, who had an abnormal Pap test followed by colposcopy or surgical procedure, diagnosed with pre-cancer or invasive cervical cancer / Total number of women, 21-69 years old, who had an abnormal Pap test followed by colposcopy or surgical procedure) x 100 = Positive Predictive Value
Standardized Rate Calculation N/A
Unit Percentage (%)
Data sources
  • ​​Cytobase – Pap tests
  • OHIP CHDB – Colposcopy and surgical procedures involving the cervix
  • OCR (Ontario Cancer Registry)  – Resolved cancer cases
  • RPDB (Registered Persons Database)  – Patient demographics
  • PCCF+, version 6D - Residence and socio-demographic information
Time Frame 2012-2015
Geographic Scale
  1. Provincial (Ontario)
  2. LHIN of residence
Denominator description Total number of Ontario screen-eligible women, 21-69 years old, who had an abnormal Pap test result followed by a colposcopy or a surgical procedure involving the cervix within 6 months of the Pap test.
  • Women, 21-69 years old, who had a Pap test with an abnormal result followed by colposcopy or surgical procedure involving the cervix within 6 months of the Pap test in a reporting period.
  • Abnormal Pap tests include both low grade and high grade Pap tests.
  • Abnormal Pap test was followed by a colposcopy or a cervical surgical procedure (e.g. cervical biopsy, endocervical biopsy, LEEP, cone biopsy or hysterectomy) within 6 months of the Pap test.
  • Colposcopy and treatment were defined through OHIP using the below fee codes:

Colposcopy

  • Z731 - Initial investigation of abnormal cytology of vulva and/or vagina or cervix under colposcopic technique with or without biopsy(ies) and/or endocervical curetting
  • Z787 - Follow-up colposcopy with biopsy(ies) with or without endocervical curetting
  • Z730 - Follow-up colposcopy without biopsy with or without endocervical curetting

Treatment

  • Z732 - Cryotherapy
  • Z724 - Electro
  • Z766 - Electrosurgical Excision Procedure (LEEP)
  • S744 - Cervix - cone biopsy - any technique, with or without D&C
  • Z720 - Cervix - Biopsy - with or without fulguration
  • Z729 - Cryoconization, electroconization or CO2 laser therapy with or without curettage for premalignant lesion (dysplasia or carcinoma in situ), out-patient procedure

Exclusions:

  • Women with a missing or invalid HIN, date of birth, LHIN or postal code.
  • Women with an invasive cervical cancer before the Pap date; diagnosis of cervical cancer was defined as: ICD-O-3 codes C53, a morphology indicative of cervical cancer, microscopically confirmed with a path report.
  • Women with a hysterectomy before the Pap date.
  • Women with a hysterectomy were identified through OHIP, using the following fee codes:
    • E862A – When hysterectomy is performed laparoscopically, or with laparoscopic assistance
    • P042A – Obstetrics – labour – delivery – caesarean section including hysterectomy
    • Q140A – Exclusion code for enrolled female patients aged 35-70 with hysterectomy
    • S710A – Hysterectomy - with or without adnexa (unless otherwise specified) – with omentectomy for malignancy
    • S727A – Ovarian debulking for stage 2C, 3B or 4 ovarian cancer and may include hysterectomy
    • S757A – Hysterectomy – with or without adnexa (unless otherwise specified) – abdominal – total or subtotal
    • S758A – Hysterectomy - with or without adnexa (unless otherwise specified) – with anterior and posterior vaginal repair and including enterocoele and/or vault prolapse repair when rendered
    • S759A - Hysterectomy - with or without adnexa (unless otherwise specified) – with anterior or posterior vaginal repair and including enterocoele and/or vault prolapse repair when rendered
    • S762A - Hysterectomy - with or without adnexa (unless otherwise specified) – radical trachelectomy - excluding node dissection
    • S763A - Hysterectomy - with or without adnexa (unless otherwise specified) – radical (Wertheim or Schauta) - includes node dissection
    • S765A – Amputation of cervix
    • S766A- Cervix uteri - Exc - cervical stump – abdominal
    • S767A- Cervix uteri - exc - Cervical stump – vaginal
    • S816A - Hysterectomy - with or without adnexa (unless otherwise specified) – vaginal
  • Women with a normal, unsatisfactory, endometrial or other abnormalities that were not indicative of cervical abnormalities.
Numerator description Total number of screen-eligible women with an abnormal Pap test result, 21 to 69 years old, who were diagnosed with pre-cancer or invasive cervical cancer after a follow up colposcopy or a surgical procedure involving the cervix.

Women with invasive cervical cancer
  • Defined as ICD-O-3 code C53 with a behaviour code=3

Women with pre-cancer

  • Defined as ICD-O-3 code C53 with a behaviour code=2 and NAACCR_MOC_CD=1 (Histology, Autopsy, Pathology, Biopsy)

Cervical cancers were counted if date of cervical cancer diagnosis in OCR occurred between 7 days before and up to 3 months after colposcopy or within ± 7 days of the surgical procedure

Considerations  N/A
Data availability & limitations
  • Pap test results are available in CytoBase only.
  • CytoBase includes only Pap tests analyzed in community-based laboratories in Ontario; Pap tests analyzed in Ontario hospitals and Community Health Centres are not captured in CytoBase.
CSQI Year 2018