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1. A Cervical Cancer Decision Model to Inform Recommendations About Preventive Services
2. The Natural History of Cervical Cancer
3. Natural history
New screening tests
HPV tests
Cervical cytology tests
Vaccination
Guidelines
What age to begin screening
What age to end screening
Screening frequency
Why a Decision Model for Cervical Cancer?
4. 3 screening tests *
15 different ages to start screening *
8 different ages to end screening =
1 big headache + insufficient funds
An RCT for Every Combination is Impossible
5. What is a Model?
6. State Transition Model
7. The Duke Cervical Cancer Model Markov state transition model of HPV, cervical pre-cancer and cancer
Can account for impact of screening and vaccination
Original model developed for 1999 AHRQ evidence report on new cervical cancer screening technologies by Evan Myers, MD, MPH (Professor, Duke University)
Validated by comparing outcomes to
Reported outcomes (e.g., SEER)
Outcomes predicted by other independently developed models
Used by a number of different academic groups and by government agencies and pharmaceutical companies
Limitations
Reflects clinical practice and includes CIN 1 as a state
Scientifically moving toward defining CIN 3 as the only true pre-cancer state
Data are grouped into age categories that may be blunt to one-year age differences
8. Life-years gained
With screening and treatment, more women
survive for a longer time
Model calculates average life-expectancy for the cohort with and without screening and treatment
LYG is difference between these two
Colposcopies – Task Force measure of burden of screening
Cost – traditional measure of resources used
How Do We Use the Model to Calculate an Outcome?
9. Current Recommendations (2003) Direct evidence to determine the optimal starting and stopping age and interval for screening is limited. Indirect evidence suggests most of the benefit can be obtained by beginning screening within 3 years of onset of sexual activity or age 21 (whichever comes first) and screening at least every 3 years
The USPSTF recommends against routinely screening women older than age 65 for cervical cancer if they have had adequate recent screening with normal Pap smears and are not otherwise at high risk for cervical cancer
The USPSTF concludes that the evidence is insufficient to recommend for or against the routine use of new technologies to screen for cervical cancer
10. Questions posed by USPSTF Age to begin cervical cancer screening
Age to end cervical cancer screening
Role of HPV tests in primary screening and triage of abnormal cytology results
Role of liquid-based cytology
11. Communicating with the TF….
12. Issues in Answering the TF Questions Evidence Report for Screening Tests
Oregon EPC
Use the data from this report for the model
Need to coordinate so that the findings are consistent
Short time frame
Original time frame of 3 months
The “oh you have a model” syndrome
Change in model structure
Change in questions and output requested
Keeping up with an onslaught of HPV and cervical cancer studies
13. Results: Age to Begin Screening
14. Results: Age to End Screening
15. Results: Age to End Screening
16. Results: HPV DNA Tests
17. Results: Liquid vs. Conventional Cytology
18. Summary of Model Results Age 21, screening q3 depends on measure used
Little benefit to screening well screened women after age 65
HPV testing for women with ASCUS confirmed; role in primary screening remains unclear
Preference for screening using conventional or LBC depends on classification of CIN 1
19. What outcome?
Colposcopies similar to colonoscopies?
How do current guidelines affect findings?
ASCCP guidelines for Age 21
How do we compare our results with others?
Cost per life-year
Shortcomings of the Current Approach
20. Natural history
Role of CIN 1
Vaccination
Need to change/construct new model(s)
Shortcomings (?) of the Current Model
21. Acknowledgements Laura Havrilesky, MD, Duke University
Evan Myers, MD, Duke University
Julian Irvine, Duke University
Task Force esp. George Sawaya, MD and Diana Petitti MD, PhD
AHRQ: Tracy Wolff, MD, Tess Miller DrPh and Mary Barton, MD; CDC: Mona Saraiya, MD, MPH
Funded by the United States Centers for Disease Control and Prevention and the Agency for Healthcare Research and Quality
Shalini Kulasingam is supported by NCI grant K07-CA113773