Cost-Effectiveness Analysis Comparing Biopsy in Advance of Ablation with Concurrent Biopsy and Ablation for Small Renal Masses Measuring 1-3 cm.

PURPOSE: To analyze the cost effectiveness of performing a renal mass biopsy in advance of ablation or concurrently with a percutaneous ablation procedure for the management of small renal masses (SRMs). MATERIALS AND METHODS: A decision-analytic model was developed with a cohort of 65-year-old male patients with an incidental, unilateral 1-3 cm SRM. A decision tree modeled the first year of clinical intervention, after which patients entered a Markov model with a lifetime horizon. Patients were assumed to be treated in accordance with established clinical practice guidelines, including surveillance, repeat ablation for recurrence, and systemic therapy for metastasis. Healthcare cost and utility values were determined from published literature or local hospital estimates, discounted at 1.5%. Total lifetime costs were calculated from the perspective of a Canadian healthcare payer and converted to 2022 Canadian dollars (C$). The primary outcome was incremental cost-effectiveness ratio (ICER) at a willingness-to-pay threshold of C$50,000 per quality-adjusted life year (QALY) gained. The secondary outcome was ICER at a willingness-to-pay threshold of C$50,000 per life year (LY) gained. RESULTS: Concurrent biopsy and ablation resulted in a gain of 16.4 quality-adjusted days, at an incremental cost of $386, with an ICER of C$8,494/QALY. The concurrent strategy was the dominant strategy for a prevalence of benign mass of <5%. Sequential biopsy and ablation was only cost-effective when LYs were not quality-adjusted and ablation cost was >C$4,300 or benign mass prevalence was >28%. CONCLUSIONS: Concurrent biopsy and ablation is cost-effective relative to pretreatment diagnostic biopsy for management of incidental SRMs.

A forecasting tool for a hospital to plan inbound transfers of COVID-19 patients from other regions.

BACKGROUND: In April 2021, the province of Ontario, Canada, was at the peak of its third wave of the COVID-19 pandemic. Intensive Care Unit (ICU) capacity in the Toronto metropolitan area was insufficient to handle local COVID patients. As a result, some patients from the Toronto metropolitan area were transferred to other regions. METHODS: A spreadsheet-based Monte Carlo simulation tool was built to help a large tertiary hospital plan and make informed decisions about the number of transfer patients it could accept from other hospitals. The model was implemented in Microsoft Excel to enable it to be widely distributed and easily used. The model estimates the probability that each ward will be overcapacity and percentiles of utilization daily for a one-week planning horizon. RESULTS: The model was used from May 2021 to February 2022 to support decisions about the ability to accept transfers from other hospitals. The model was also used to ensure adequate inpatient bed capacity and human resources in response to various COVID-related scenarios, such as changes in hospital admission rates, managing the impact of intra-hospital outbreaks and balancing the COVID response with planned hospital activity. CONCLUSIONS: Coordination between hospitals was necessary due to the high stress on the health care system. A simple planning tool can help to understand the impact of patient transfers on capacity utilization and improve the confidence of hospital leaders when making transfer decisions. The model was also helpful in investigating other operational scenarios and may be helpful when preparing for future outbreaks or public health emergencies.

Emergency department use following incentives to provide after-hours primary care: a retrospective cohort study.

BACKGROUND: Access to primary care outside of regular working hours is limited in many countries. This study investigates the relation between the after-hours premium, an incentive for primary care physicians to provide services after hours, and less-urgent visits to the emergency department in Ontario, Canada. METHODS: We analyzed a retrospective cohort of a random sample of Ontario residents from April 2002 to March 2006, and a subcohort of patients followed from April 2005 to March 2016. We linked patient and primary care physician data with emergency department visit data. We used fixed-effects regression models to analyze the association between the introduction of the after-hours premium, as well as subsequent increases in the value of the premium, and the number of monthly emergency department visits. RESULTS: The sample consisted of 586 534 patients between 2002 and 2006, and 201 594 patients from 2005 to 2016. After controlling for patient and physician characteristics, seasonality and time-invariant patient confounding factors, introduction of the after-hours premium was associated with a reduction of 1.26 less-urgent visits to the emergency department per 1000 patients per month (95% confidence interval -1.48 to -1.04). Most of this reduction was observed in after-hours visits. Sensitivity analysis showed that the monthly reduction in less-urgent visits to the emergency department was in the range of -1.24 to -1.16 per 1000 patients. Subsequent increases in the after-hours premium were associated with a small reduction in less-urgent visits to the emergency department. INTERPRETATION: Ontario's experience suggests that incentivizing physicians to improve access to after-hours primary care reduces some less-urgent visits to the emergency department. Other jurisdictions may consider incentives to limit less-urgent visits to the emergency department.

Cost-effectiveness analysis of multigene expression profiling assays to guide adjuvant therapy decisions in women with invasive early-stage breast cancer.

Gene expression profiling (GEP) testing using 12-gene recurrence score (RS) assay (EndoPredict®), 58-gene RS assay (Prosigna®), and 21-gene RS assay (Oncotype DX®) is available to aid in chemotherapy decision-making when traditional clinicopathological predictors are insufficient to accurately determine recurrence risk in women with axillary lymph node-negative, hormone receptor-positive, and human epidermal growth factor-receptor 2-negative early-stage breast cancer. We examined the cost-effectiveness of incorporating these assays into standard practice. A decision model was built to project lifetime clinical and economic consequences of different adjuvant treatment-guiding strategies. The model was parameterized using follow-up data from a secondary analysis of the Anastrozole or Tamoxifen Alone or Combined randomized trial, cost data (2017 Canadian dollars) from the London Regional Cancer Program (Canada) and secondary Canadian sources. The 12-gene, 58-gene, and 21-gene RS assays were associated with cost-effectiveness ratios of $36,274, $48,525, and $74,911/quality-adjusted life year (QALY) gained and resulted in total gains of 379, 284.3, and 189.5 QALYs/year and total budgets of $12.9, $14.2, and $16.6 million/year, respectively. The total expected-value of perfect information about GEP assays' utility was $10.4 million/year. GEP testing using any of these assays is likely clinically and economically attractive. The 12-gene and 58-gene RS assays may improve the cost-effectiveness of GEP testing and offer higher value for money, although prospective evidence is still needed. Comparative field evaluations of GEP assays in real-world practice are associated with a large societal benefit and warranted to determine the optimal and most cost-effective assay for routine use.

Stirring the pot: Switching from blended fee-for-service to blended capitation models of physician remuneration.

In Canada's most populous province, Ontario, family physicians may choose between the blended fee-for-service (Family Health Group [FHG]) and blended capitation (Family Health Organization [FHO] payment models). Both models incentivize physicians to provide after-hours (AH) and comprehensive care, but FHO physicians receive a capitation payment per enrolled patient adjusted for age and sex, plus a reduced fee-for-service while FHG physicians are paid by fee-for-service. We develop a theoretical model of physician labor supply with multitasking to predict their behavior under FHG and FHO, and estimable equations are derived to test the predictions empirically. Using health administrative data from 2006 to 2014 and a two-stage estimation strategy, we study the impact of switching from FHG to FHO on the production of a capitated basket of services, after-hours services and nonincentivized services. Our results reveal that switching from the FHG to FHO reduces the production of capitated services to enrolled patients and services to nonenrolled patients by 15% and 5% per annum and increases the production of after-hours and nonincentivized services by 8% and 15% per annum.

The impact of pharmaceutical marketing on market access, treatment coverage, pricing, and social welfare.

Pharmaceutical spending in the United States, Canada, and the EU is growing. Public payers cover a large portion of these costs and have responded by instituting various pricing and access policies to limit their expenditure. One challenge that public payers face is additional demand induced by a manufacturer's marketing effort. We use a game theoretic approach to study the impact of pharmaceutical marketing on six practical pricing and access policies: negotiated pricing, open pricing, controlled pricing, a listing process, a risk-sharing arrangement, and a value-based pricing with risk-sharing arrangement. We find that all non-value-based policies result in either restricted access or suboptimal treatment coverage. We find that marketing is the highest in the first-best setting where all decisions are made by a social planner. We also find that the value-based pricing with risk-sharing arrangement is preferred by the manufacturer and from a societal perspective whereas no policy is universally preferred by a health care payer. A value-based pricing with risk-sharing arrangement always results in zero net monetary benefit for a health care payer. Therefore, considering non-value-based arrangements, we find that a negotiated pricing policy, a controlled pricing policy, or a risk-sharing arrangement may be socially preferred.

Predicting patterns of service utilization within children's mental health agencies.

BACKGROUND: Some children with mental health (MH) problems have been found to receive ongoing care, either continuously or episodically. We sought to replicate patterns of MH service use over extended time periods, and test predictors of these patterns. METHODS: Latent class analyses were applied to 4 years of visit data from five MH agencies and nearly 6000 children, 4- to 13-years-old at their first visit. RESULTS: Five patterns of service use were identified, replicating previous findings. Overall, 14% of cases had two or more episodes of care and 23% were involved for more than 2 years. Most children (53%) were seen for just a few visits within a few months. Two patterns represented cases with two or more episodes of care spanning multiple years. In the two remaining patterns, children tended to have just one episode of care, but the number of sessions and length of involvement varied. Using discriminant function analyses, we were able to predict with just over 50% accuracy children's pattern of service use. Severe externalizing behaviors, high impairment, and high family burden predicted service use patterns with long durations of involvement and frequent visits. CONCLUSIONS: Optimal treatment approaches for children seen for repeated episodes of care or for care lasting multiple years need to be developed. Children with the highest level of need (severe pathology, impairment, and burden) are probably best served by providing high intensity services at the start of care.

Trends in obesity and multimorbidity in Canada.

Very few studies have examined trends in multimorbidity over time and even fewer have examined trends over time across different body mass index (BMI) groups. Given a general decline in death rates but increased cardiovascular risk factors among individuals with obesity, the trend in the association between obesity and multimorbidity is hypothesized to be increasing over time. The data for our study came from the 1996-97 National Population Health Survey and the 2005 and 2012-13 Canadian Community Health Surveys (N = 277,366 across all 3 surveys). We examined trends in the association between BMI groups and multimorbidity using a logistic regression model. We also investigated trends in the prevalence of specific chronic conditions, pairs of chronic conditions and different levels of multimorbidity across BMI groups. We found significantly greater levels of multimorbidity in 2005 (OR = 1.42; p < 0.001) and 2012-13 (OR = 1.58; p < 0.001) relative to 1996-97. Changes in multimorbidity levels were much greater among individuals with class II/III (OR = 1.48; p = 0.005) and class I obesity (OR = 1.38; p = 0.001) in 2012-13 relative to 1996-97. Much of the increase in multimorbidity among individuals living with obesity was due to increases in 3+ chronic conditions and conditions in combination with hypertension, and the greatest increase was found among seniors living with obesity. Our results highlight the need for interventions aimed at preventing obesity and the prevention of chronic conditions among individuals with obesity, especially among seniors.

Evaluation of a pharmaceutical risk-sharing agreement when patients are screened for the probability of success.

We analyze a game-theoretic model of a risk-sharing agreement between a payer and a pharmaceutical firm. The drug manufacturer chooses the price while the payer sets the rebate rate and decides which patients are eligible for treatment. The manufacturer provides the payer with a rebate for nonresponding patients. We generalize on the existing literature, by making both price and rebate rate decision variables, allowing the rebate rate to be different from 100%, and incorporating 2 types of administrative costs. We identify a threshold for the expected probability of response for classifying the drug as a mass-market or niche type and investigate the optimal solutions for both types. We also identify a threshold for the rebate rate at which the net benefits become equal for responding and nonresponding patients. Through numerical examples, we examine how various parameters impact the drug manufacturer's and the payer's optimal solution.

Identification and survival outcomes of a cohort of patients with cancer of unknown primary in Ontario, Canada.

BACKGROUND: Cancer of unknown primary origin (CUP) is defined by the presence of pathologically identified metastatic disease without clinical or radiological evidence of a primary tumour. Our objective was to identify incident cases of CUP in Ontario, Canada, and determine the influence of histology and sites of metastases on overall survival (OS). MATERIAL AND METHODS: We used the Ontario Cancer Registry (OCR) and the Same-Day Surgery and Discharge Abstract Database (SDS/DAD) to identify patients diagnosed with CUP in Ontario between 1 January 2000, and 31 December 2005. Patient diagnostic information, including histology and survival data, was obtained from the OCR. We cross-validated CUP diagnosis and obtained additional information about metastasis through data linkage with the SDS/DAD database. OS was assessed using Cox regression models adjusting for histology and sites of metastases. RESULTS: We identified 3564 patients diagnosed with CUP. Patients without histologically confirmed disease (n = 1821) had a one-year OS of 10.9%, whereas patients with confirmed histology (n = 1743) had a one-year OS of 15.6%. The most common metastatic sites were in the respiratory or digestive systems (n = 1603), and the most common histology was adenocarcinoma (n = 939). Three-year survival rates were 3.5%, 5.3%, 41.6% and 3.6% among adenocarcinoma, unspecified carcinoma, squamous cell carcinoma and undifferentiated histology, respectively. Three-year survival rates were 40%, 2.4%, 8.0% and 4.6% among patients with metastases localised to lymph nodes, the respiratory or digestive systems, other specified sites, and unspecified sites, respectively. CONCLUSION: CUP patients in Ontario have a poor prognosis. Some subgroups may have better survival rates, such as patients with metastases localised to lymph nodes and patients with squamous cell histology.

The Effect of Leisure-Time Physical Activity on Obesity, Diabetes, High BP and Heart Disease Among Canadians: Evidence from 2000/2001 to 2005/2006.

Although studies have looked at the effect of physical activity on obesity and other health outcomes, the causal nature of this relationship remains unclear. We fill this gap by investigating the impact of leisure-time physical activity (LTPA) and work-related physical activity (WRPA) on obesity and chronic conditions in Canadians aged 18-75 using instrumental variable and recursive bivariate probit approaches. Average local temperatures surrounding the respondents' interview month are used as a novel instrument to help identify the causal relationship between LTPA and health outcomes. We find that an active level of LTPA (i.e., walking ≥1 h/day) reduces the probability of obesity by five percentage points, which increases to 11 percentage points if also combined with some WRPA. WRPA exhibits a negative effect on the probability of obesity and chronic conditions.

Defining Episodes of Care in Children's Mental Health Using Administrative Data.

Criteria to define an episode of care in children's mental health services are needed. Various criteria were applied to 5 years of visit data from children 4-11 years (N = 5,206) at their first visit to 1 of 3 children's mental health agencies. A minimum of 3 visits with 180 days between episodes optimized agreement with other dates (e.g., telephone intake assessment) marking the start and end of an episode, and clinician-rated number of episodes. Grouping visits into episodes provides a clearer representation of how services are distributed over extended periods of time, facilitating research and enhancing accuracy in service planning.

Primary care services and emergency department visits in blended fee-for-service and blended capitation models: evidence from Ontario, Canada.

INTRODUCTION: It is well-known that the way physicians are remunerated can affect delivery of health care services to the population. Fee-for-service (FFS) generally leads to oversupply of services, while capitation leads to undersupply of services. However, little evidence exists on the link between remuneration and emergency department (ED) visits. We fill this gap using two popular blended models introduced in Ontario, Canada: the Family Health Group (FHG), an enhanced/blended FFS model, and Family Health Organization (FHO), a blended capitation model. We compare primary care services and rates of emergency department ED visits between these two models. We also evaluate whether these outcomes vary by regular- and after-hours, and patient morbidity status. METHODS: Physicians practicing in an FHG or FHO between April 2012 and March 2017 and their enrolled adult patients were included for analyses. The covariate-balancing propensity score weighting method was used to remove the influence of observable confounding and negative-binomial and linear regression models were used to evaluate the rates of primary care services, ED visits, and the dollar value of primary care services delivered between FHGs and FHOs. Visits were stratified as regular- and after-hours. Patients were stratified into three morbidity groups: non-morbid, single-morbid, and multimorbid (two or more chronic conditions). RESULTS: 6184 physicians and their patients were available for analysis. Compared to FHG physicians, FHO physicians delivered 14% (95% CI 13%, 15%) fewer primary care services per patient per year, with 27% fewer services during after-hours (95% CI 25%, 29%). Patients enrolled to FHO physicians made 27% more less-urgent (95% CI 23%, 31%) and 10% more urgent (95% CI 7%, 13%) ED visits per patient per year, with no difference in very-urgent ED visits. Differences in the pattern of ED visits were similar during regular- and after-hours. Although FHO physicians provided fewer services, multimorbid patients in FHOs made fewer very-urgent and urgent ED visits, with no difference in less-urgent ED visits. CONCLUSION: Primary care physicians practicing in Ontario's blended capitation model provide fewer primary care services compared to those practicing in a blended FFS model. Although the overall rate of ED visits was higher among patients enrolled to FHO physicians, multimorbid patients of FHO physicians make fewer urgent and very-urgent ED visits.

Cost-Effectiveness Analysis of Pharmacogenomics (PGx)-Based Warfarin, Apixaban, and Rivaroxaban Versus Standard Warfarin for the Management of Atrial Fibrillation in Ontario, Canada.

OBJECTIVE: To assess the cost-effectiveness of pharmacogenomics (PGx)-based warfarin (i.e., warfarin dosing following genetic testing), apixaban, and rivaroxaban oral anticoagulation versus standard warfarin for the treatment of newly diagnosed patients with nonvalvular atrial fibrillation (AF) aged ≥ 65 years. METHODS: We developed a Markov decision-analytic model to compare costs [2017 Canadian dollars (C$)] and quality-adjusted life years (QALYs) from the Ontario health care payer perspective over a life-time horizon. The parameters used in the model were derived from the published literature, the Ontario health care administrative database, and expert opinion. To account for the uncertainty of model parameters, we conducted extensive deterministic and probabilistic sensitivity analyses. The results were summarized using incremental cost-effectiveness ratios (ICERs) and cost-effectiveness acceptability curves. RESULTS: We found that PGx-based warfarin had an ICER of C$17,584/QALY compared with standard warfarin, and apixaban had an ICER of C$64,590/QALY compared with PGx-based warfarin in our base-case analysis. Rivaroxaban was extendedly dominated by PGx-based warfarin and apixaban. The probabilistic sensitivity analysis showed that apixaban, rivaroxaban, PGx-based warfarin, and standard warfarin were cost-effective at some willingness-to-pay (WTP) thresholds. PGx-based warfarin had a higher probability of being cost-effective than apixaban (51.3% versus 14.3%) at a WTP threshold of C$50,000/QALY. At a WTP threshold of C$100,000/QALY, apixaban had a higher probability of being cost-effective than PGx-based warfarin (54.6% versus 22.6%). CONCLUSION: We found that PGx-based warfarin for patients with AF is cost-effective at a WTP threshold of C$50,000/QALY. Apixaban had a higher probability of being cost-effective (> 50%) at a WTP threshold of C$93,000/QALY.

The use of health utility in cost-utility analysis: A systematic review in substance use disorders.

BACKGROUND AND AIM: We aim to identify within-trial and modelled Cost-Utility Analysis (CUA) in substance use disorders (SUD) and review the applicability assessment associated with health utility used in modelled CUA. STUDY DESIGN AND METHODS: We searched Medline, Embase, EconLit and the Pharmaceutical Benefits Advisory Committee (PBAC) databases. A global systematic literature search was undertaken to determine the CUA of SUD interventions. Key characteristics of the studies and use of health utility were described. The applicability assessment associated with health utility used in modelled CUA was reviewed using The Health Utility Application Tool (HAT). RESULTS: The final review retrieved 49 CUA (14 within-trial and 35 modelled CUA). Three major health utility measurements were used - standard gamble, EQ-5D-5L and SF-6D. EQ-5D-5L was mainly used in within-trial CUA, whereas standard gamble, EQ-5D-5L and SF-6D were equally cited in modelled CUA and within-trial CUA. Twenty-nine articles using modelled CUA citing health utilities from published literature were assessed. Only half and one-third of CUA studies described the type of quality-of-life measure and value sets used in health utility studies, respectively. Only two-thirds showed the authors addressed questions about the similarities in clinical conditions, and health state description between health utility studies and economic evaluation studies. CONCLUSION: Justifications for chosen health utilities in modelled CUA studies were mostly absent in SUD. We suggested health economists use the HAT to make judgements when assessing health utility from published estimates. The use of this tool will increase the reliability of economic evaluation carried out to assist government and policymakers in making informed decisions around health topics.

Randomized trial of distance-based treatment for young children with discipline problems seen in primary health care.

OBJECTIVE: Many parents of preschool-age children have concerns about how to discipline their child but few receive help. We examined the effects of a brief treatment along with usual care, compared with receiving usual care alone. Patients. Parents (N = 178) with concerns about their 2- to 5-year olds' discipline were recruited when they visited their family physician at 1 of 24 practices. METHODS: After completing mailed baseline measures, parents were randomly assigned to receive usual care or the Parenting Matters intervention along with usual care. Parenting Matters combined a self-help booklet with two calls from a telephone coach during a 6-week treatment period. Follow-up assessments were completed at 7 weeks post-randomization, and 3 and 6 months later. RESULTS: Behaviour problems (Eyberg Child Behaviour Inventory) decreased significantly more in the Parenting Matters condition compared with Usual Care alone, based on a significant time by treatment group effect in intent-to-treat, growth curve analyses (P = 0.033). The Parenting Matters group also demonstrated greater and more rapid improvement than in usual care alone in terms of overall psychopathology (Child Behaviour Checklist, P = 0.02), but there were no group differences in parenting. The overall magnitude of group differences was small (d = 0.15 or less). CONCLUSION: A brief early intervention combining a self-help booklet and telephone coaching is an effective way to treat mild behaviour problems among young children. This minimal-contact approach addresses the need for interventions in primary health care settings and may be a useful component in step-care models of mental health.

Forecasting ICU Census by Combining Time Series and Survival Models.

Capacity planning of ICUs is essential for effective management of health safety, quality of patient care, and the allocation of ICU resources. Whereas ICU length of stay (LOS) may be estimated using patient information such as severity of illness scoring systems, ICU census is impacted by both patient LOS and arrival patterns. We set out to develop and evaluate an ICU census forecasting algorithm using the Multiple Organ Dysfunction Score (MODS) and the Nine Equivalents of Nursing Manpower Use Score (NEMS) for capacity planning purposes. DESIGN: Retrospective observational study. SETTING: We developed the algorithm using data from the Medical-Surgical ICU (MSICU) at University Hospital, London, Canada and validated using data from the Critical Care Trauma Centre (CCTC) at Victoria Hospital, London, Canada. PATIENTS: Adult patient admissions (7,434) to the MSICU and (9,075) to the CCTC from 2015 to 2021. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We developed an Autoregressive integrated moving average time series model that forecasts patients arriving in the ICU and a survival model using MODS, NEMS, and other factors to estimate patient LOS. The models were combined to create an algorithm that forecasts ICU census for planning horizons ranging from 1 to 7 days. We evaluated the algorithm quality using several fit metrics. The root mean squared error ranged from 2.055 to 2.890 beds/d and the mean absolute percentage error from 9.4% to 13.2%. We show that this forecasting algorithm provides a better fit when compared with a moving average or a time series model that directly forecasts ICU census. Additionally, we evaluated the performance of the algorithm using data during the global COVID-19 pandemic and found that the error of the forecasts increased proportionally with the number of COVID-19 patients in the ICU. CONCLUSIONS: It is possible to develop accurate tools to forecast ICU census. This type of algorithm may be important to clinicians and managers when planning ICU capacity as well as staffing and surgical demand planning over a short time horizon.

Cost-effectiveness of a 21-gene recurrence score assay versus Canadian clinical practice in women with early-stage estrogen- or progesterone-receptor-positive, axillary lymph-node negative breast cancer.

BACKGROUND: A 21-gene recurrence score (RS) assay may inform adjuvant systematic treatment decisions in women with early stage breast cancer. We sought to investigate the cost effectiveness of using the RS-assay versus current clinical practice (CCP) in women with early-stage estrogen- or progesterone-receptor-positive, axilliary lymph-node negative breast cancer (ER+/ PR + LN- ESBC) from the perspective of the Canadian public healthcare system. METHODS: We developed a Markov model to project the lifetime clinical and economic consequences of ESBC. We evaluated adjuvant therapy separately in post- and pre-menopausal women with ER+/ PR + LN- ESBC. We assumed that the RS-assay would reclassify pre- and post-menopausal women among risk levels (low, intermediate and high) and guide adjuvant systematic treatment decisions. The model was parameterized using 7 year follow up data from the Manitoba Cancer Registry, cost data from Manitoba administrative databases, and secondary sources. Costs are presented in 2010 CAD. Future costs and benefits were discounted at 5%. RESULTS: The RS-assay compared to CCP generated cost-savings in pre-menopausal women and had an ICER of $60,000 per QALY gained in post-menopausal women. The cost effectiveness was most sensitive to the proportion of women classified as intermediate risk by the RS-assay who receive adjuvant chemotherapy and the risk of relapse in the RS-assay model. CONCLUSIONS: The RS-assay is likely to be cost effective in the Canadian healthcare system and should be considered for adoption in women with ER+/ PR + LN- ESBC. However, ongoing assessment and validation of the assay in real-world clinical practice is warranted.