COST-EFFECTIVENESS OF LIQUID-BASED CYTOLOGY WITH AUTOMATED GUIDED SCREENING FOR CERVICAL CANCER PREVENTION IN CANADA D. Fontaine 1 , C. Naugler 1 , E.A. Baginska 2 1. Department of Pathology, University of Calgary, Calgary Laboratory Services 2. Health Economics and Outcomes Research Group, BD
Conflict of interest statement • Relevant conflicts of interest – Dr. Fontaine: Employee of Calgary Laboratory Services (CLS) – Dr. Naugler: Employee of CLS, research funding from CLS and Capital District Health Authority (Nova Scotia), travel funding from BD Canada – E.A. Baginska: Member of Health Economics and Outcomes Research Group, BD Canada
Cervical Cancer in Canada • Incidence and mortality rates for cervical cancer have continued declining, by 1.4% and 2.9% per year, respectively, since 1998 (Canadian Cancer Society, 2012). • This is largely due to widespread, regular screening, which detects premalignant and malignant lesions early so that they can be treated. • Despite this declining trend, an estimated 1350 women (7 per 100,000) will develop invasive cervical cancer and 330 (2 per 100,000) women will die each year from the disease. (Canadian Cancer Society, 2012) • Cervical cancer morbidity is also a societal concern, as it is prevalent among women aged 20-40 and can impact a woman’s ability to have children (Marett 2002).
Types of Screening Technologies used in Canada • Conventional Cytology (CC): – cervical cells obtained by spatula or brush, smeared onto a glass slide and then fixed. – limitations resulting from variable quality of the slide material (blood cells and mucus capable of obscuring the cervical cells) and uneven spread of cells. • Liquid-Based Cytology (LBC): – sample is dissipated in a fluid medium which contains fixative. – The liquid sample is then subjected to either a process which filters the cells onto a slide (ThinPrep ! LBC, Hologic, Bedford, MA, USA) or cell enrichment [Becton Dickinson (BD) SurePath ! LBC, BD, Franklin lakes, NJ, USA] producing a cleaner, more homogeneous preparation which facilitates examination of the cervical cells. • HPV Testing
Clinical Guidelines vary in Canada • There are no standard guidelines across all provinces and territories in Canada. • Type of Technology : – Some provinces use conventional cytology as a primary screen, while others use LBC as a primary screen. – Some provinces are using HPV testing as a secondary screen to triage positive cytology samples. • Screening Interval : – Since the 1960s, guidelines have indicated that women should be screened annually. – Using analyses from a comprehensive decision analytic model produced by the Duke University Evidence-Based Practice Center, the United States Preventative Services Task Force concluded that the harms associated with over-screening out-way the benefits of annual screening in the general population. A similar conclusion was made by the Program in Evidence-Based Care at Cancer Care Ontario (CCO). – Based on this supporting evidence, several provinces have, or are in the process of, extending screening intervals from an annual basis to three year intervals.
Automated Guided Screening • Current screening techniques are time-consuming and require a large and committed laboratory workforce. • Despite the effectiveness of the screening program, cytotechnologists have often felt under pressure, particularly when failures receive media attention (Kitchener 2011). • Automated guided screening technologies use computer algorithms to identify slides that have the highest likelihood of containing cytological abnormalities. • These technologies have been reported to improve lab productivity (Kitchener 2011, Wong 2012) and improve sensitivity to detect cytological abnormalities (Wilbur 2009).
Overview of Technology • The FocalPoint Guided Screener Imaging System (FPGS) scans the slides and identifies those requiring further examination • Flagged slides are examined by screening staff using the BD FocalPoint Guided Screener Workstation. • The Workstation directs screening staff towards 10 electronically marked fields of view (FOVs) on the slide. • If abnormal cells are seen in any of the FOVs the entire slide is manually screened.
Research Objectives • Develop a dynamic mathematical model to determine the cost-effectiveness of incorporating an automated guided screen technology into a provincial screening algorithm • The BD FocalPoint Guided Screener Imaging System was used to represent the automated guided screening technology • Test performance data were obtained from peer- reviewed literature.
Cost-Effectiveness Model Design • Lifetime Cohort Simulation Markov Model – Follows 100,000 women throughout their lifetime – Each cycle, probabilities are used to determine how many women: • Come to screening session • Remain healthy, develop pre-cancerous lesion, cancer, or die • Have pre-cancerous lesion or cancer correctly identified by the screening test and then comply to follow-up care. – Total health care system costs are also tracked throughout the lifetime
Results Number of Predicted Cervical Cancer Deaths Number cervical cancer deaths Strategy (per 100,000) Total lifetime costs CC, no HPV triage, One Year 307.45 123,224,105.94 CC, no HPV triage, Two Year 333.05 105,101,562.63 CC, no HPV triage, Three Year 368.84 92,358,560.82 Manual LBC, no HPV triage, One Year 260.97 135,617,445.21 Various Current Manual LBC, no HPV triage, Two Year 275.06 115,684,543.01 Strategies in Canada Manual LBC, no HPV triage, Three Year 297.04 102,108,557.57 Manual LBC, HPV triage, One Year 257.79 134,096,535.83 Manual LBC, HPV triage, Two Year 272.09 114,608,198.49 Manual LBC, HPV triage, Three Year 293.62 102,021,147.63 FPGS w LBC, no HPV triage, Three Year 195.75 118,373,077.46 Proposed FPGS w LBC, HPV triage, Three Year 195.51 117,204,185.53 Strategy
Cost-Effectiveness Model Design • Proposed Strategy : – FocalPoint GS w/LBC, HPV Triage for ASCUS in women › 30 and LSIL for women › 50, Screening Interval: 3 years • Routine Screening: Analysis: Compares • More Frequent Screening: the cost-effectiveness of this strategy to various current strategies in Canada
Results Selected Current Strategy Conventional Cytology , No HPV Triage, 1 Year Interval Proposed Strategy FocalPoint GS with LBC, HPV Triage for ASCUS in women › 30 and LSIL for women › 50, 3 Year Interval Incremental Cost-Effectiveness Ratio (ICER) = Dominant (Cost Saving, Incremental QALYs added) Cost 30'000'000 • A probabilistic sensitivity 25'000'000 analysis was conducted to determine the 20'000'000 likelihood of achieving 15'000'000 stated ICER when ICERs 10'000'000 $50,000/QALY Threshold varying inputs. $20,000/QALY Threshold 5'000'000 • Based on 100 runs, the QALYs 0 -1'200 -700 -200 300 800 majority of ICERs were -5'000'000 still deemed dominant , -10'000'000 with the remaining runs showing ICER ratios -15'000'000 below commonly -20'000'000 accepted thresholds -25'000'000 -30'000'000
Results Selected Current Strategy LBC , No HPV Triage, 1 Year Interval Proposed Strategy FocalPoint GS with LBC, HPV Triage for ASCUS in women › 30 and LSIL for women › 50, 3 Year Interval Incremental Cost-Effectiveness Ratio (ICER) = Dominant (Cost Saving, Incremental QALYS added) Cost 50'000'000 • A probabilistic sensitivity 40'000'000 analysis was conducted to determine the 30'000'000 likelihood of achieving stated ICER when 20'000'000 (PSA) varying inputs. $50,000/QALY threshold 10'000'000 $20,000/QALY Threshold • Based on 100 runs, all 0 QALYs -1'000 -500 0 500 ICERs were deemed -10'000'000 dominant. -20'000'000 -30'000'000 -40'000'000 -50'000'000
Conclusions • Based on the model analysis, a strategy of using liquid-based cytology with the FocalPoint Guided Screen Imaging System, with HPV triage at 3 year intervals resulted in the lowest expected cervical cancer deaths when comparing to various current strategies. • This strategy is cost-saving and more effective than a strategy of annual conventional cytology without HPV Triage • This strategy is also cost-saving and more effective than a current strategy of annual LBC without HPV triage.
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