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Cost-Effectiveness Analyses in Nonmuscle Invasive Bladder Cancer: Comparative Assessment in the Absence of Comparative Evidence
By: Vidit Sharma, MD; Stephen A. Boorjian, MD | Posted on: 01 Jun 2021
As the therapeutic options for patients with nonmuscle invasive bladder cancer (NMIBC) expand,1 choosing the right treatment at the right time for the right patient becomes increasingly challenging. Providers must consider NMIBC risk stratification, the reported efficacy of potential treatments, side-effect profiles, costs, and logistical concerns such as the burden of scheduling, as well as patient goals. Frequent bacillus Calmette-Guérin (BCG) supply shortages and the lack of clinical trials directly comparing novel therapies further complicate decision making.
Cost-effectiveness analysis (CEA) represents a relatively underutilized yet powerful technique that has the potential to improve care for NMIBC patients. While commonly used to comment on the pricing of interventions, cost-effectiveness analyses can more importantly integrate the spectrum of clinically relevant information to inform guideline recommendations and treatment decisions for NMIBC.
Cost-effectiveness analyses–or, more appropriately, cost-utility analyses–assimilate information on the quality and quantity of life as well as cost for each treatment option. The Appendix outlines basic definitions of CEA terminology.2 A common CEA format utilizes Markov models with relevant “health states” downstream of each treatment option. The figure is a schematic of sample NMIBC health states such as recurrence, progression, and toxicity. Each health state is ascribed unique costs and a utility value, which reflects the quality of life for the given state. The probability of transitioning between health states for each time cycle in the Markov Model is derived from oncologic and toxicity data from the literature. The utility values for all health states downstream of a treatment are then summed in a probability-weighted manner for every time cycle to calculate the quality-adjusted life-years (QALYs) for the given treatment. A similar summation is performed for costs. The “expected” QALYs and costs for treatments can then be compared using the Incremental Cost-Effectiveness Ratio (ICER), which is the difference in cost divided by the difference in QALYs between 2 treatments. Treatments with an ICER of less than $100,000 per additional QALY (the conventional willingness to pay threshold) are considered cost-effective.
Although this approach may seem abstract, the resulting models are particularly useful in NMIBC decision making. For example, given frequent BCG shortages, and the resulting emphasis on conservation and appropriate allocation of supply,3 we conducted a CEA evaluating maintenance BCG for intermediate and high risk NMIBC.4 We found that maintenance BCG only became cost-effective if it reduced 5-year progression by at least 2.1%. Given the modest effect size of maintenance BCG on progression, we reasoned that maintenance BCG is likely only cost-effective for subsets of high risk NMIBC with a significant risk of 5-year progression and can likely be foregone for intermediate risk NMIBC, especially during times of BCG shortage. In fact, further probabilistic sensitivity analysis demonstrated that maintenance BCG was only cost-effective in ∼17% of intermediate and high risk NMIBC simulations. In this way, the CEA not only identified which patients would benefit most from maintenance BCG treatments, but also aligned with American Urological Association policy statements on the matter.5
Moreover, determining treatment for patients with BCG-unresponsive NMIBC represents another significant opportunity for CEA utilization. Here, the decision making remains challenging as the U.S. Food and Drug Administration has permitted single-arm trials to be used for agent approval,6 causing the number of agents being tested in this disease space to increase rapidly. CEAs thereby offer the opportunity to contextualize the results of the existing and emerging single-arm trials to standards of care, such as radical cystectomy or salvage intravesical chemotherapy. As a proof of concept, we recently evaluated the cost-effectiveness of pembrolizumab relative to radical cystectomy and intravesical gemcitabine-docetaxel for patients with BCG-unresponsive carcinoma in situ.7 We found that pembrolizumab was not cost-effective relative to radical cystectomy (ICER $1,403,008) or intravesical gemcitabine-docetaxel (ICER $2,011,923), regardless of cystectomy eligibility status. Its marginal benefit (0.10 QALYs) over radical cystectomy was not justified by its high cost and high risk of adverse events. In fact, a greater than 90% price reduction would be required to render pembrolizumab cost-effective for this indication. However, we did find that intravesical gemcitabine-docetaxel, based on retrospective multi-institutional data,8 was cost-effective in about 46% of simulations vs radical cystectomy and warrants further study as a treatment option. Thus, by quantifying the balance of side-effects, oncologic benefit, and cost relative to existing standards of care, CEAs can help interpret single-arm trial data for BCG-unresponsive NMIBC and guide future treatment selection.
Other potential uses for CEAs in BCG-unresponsive NMIBC include testing the relative importance of various oncologic endpoints over complete response thresholds, which may improve trial design.6 In addition, CEAs may be incorporated into shared decision making tools (akin to WiserCare© in prostate cancer) that weigh treatment risks and benefits according to an individual patient’s preferences to help patients decide between treatment options. CEAs may also provide rough estimates of expected costs for patients, thereby assisting in patient counseling. Considering that NMIBC is one of the most expensive cancers on a per-patient level, CEAs can as well inform personalized surveillance schedules for NMIBC patients.
Importantly, CEAs are limited by the quality of data used for the modeling, including the oncologic and cost data sources. A particularly critical limitation is the utility value data, which can vary widely depending on the method used to derive the utility values9 and thus alter expected QALY calculations.10 Nevertheless, this limitation may be addressed by encouraging the collection of utility value assessments along with patient-reported outcome questionnaires in clinical trials. In addition, sensitivity analyses varying utility values over broad ranges can be conducted to determine how susceptible the model is to small changes in utility values (see table).
Appendix. Review of CEA terminology.
Term | Definition/Notes |
---|---|
Health State/Markov Node | A clinical state/scenario that can be found after the given treatment. Generally, the more granular and comprehensive the lost of health states modeled, the higher the quality of the CEA. The figure displays common health states in NMIBC. Although it is easier to think of health states as mutually exclusive, compound health states are also possible, for instance patients with both recurrence and treatment toxicity. |
Time Cycle/Markov Cycle | Corresponds to the number of iterations that participants are allowed to transition between health states. The amount of time per cycle varies based on the clinical question ranging from days to years. For NMIBC, we have chosen to use 3-month time cycles to correspond with common cystoscopic surveillance and therapy schedules. |
Time Horizon | The number of time cycles of the model that are completed before calculating the model outputs. Often this corresponds to clinically meaningful time points specific to the given cancer. When possible, a lifetime horizon is also useful to characterize the impact of an intervention over the remaining life of a patient. Such structures allow assessment of delayed impacts of interventions but also require adding more assumptions into the model. |
Transition Probability | The chance of moving from one health state to another between successive time cycles. Probabilities reported in the literature (such as 5-year risks recurrence/progression) are first converted to rates and those rates are then used to calculate per-cycle transition probabilities. |
Cost | Usually represents the monetary cost of a given treatment and a given health state. A CEA from a payer/insurer perspective generally only considers the direct costs borne by the entity. But CEAs from a societal perspective also account for other sources of financial strain, such as patient out-of-pocket costs and indirect costs such as lost wages, caregiver productivity loss and travel time. |
Utility Value | A value between 0 and 1 that represents the quality of life of a patient in a given health state, with 1 being perfect quality of life. This can be assessed with several methods, such as a rating scale, visual analog scale, formulaic conversion from quality of life questionnaires, time tradeoff, and standard gamble – each with its own set of pros and cons.9 |
QALY | The Quality Adjusted Life Year is a summation of product of the utility value and the time spent in a given health state across all health states downstream of a treatment option. Expected QALYs, also referred to as the “effectiveness” in CEAs, are then reported for each option at the final time horizon. |
ICER | The Incremental Cost Effectiveness Ratio is a summary measure comparing two options within a CEA. It is calculated by dividing the difference in costs by the difference in QALYs for two options (eg A or B): ICERA/B = ($A – $B)/(QALYA – QALYB). |
WTP Threshold | The Willingness-to-Pay Threshold represents a monetary cost a particular society is willing to pay for one additional QALY. For the US, this is frequently $100,000 per QALY but can range from $50,000 to $150,000 per QALY. If the ICER of a treatment is less than the WTP, then that treatment is considered cost-effective. |
One-Way Sensitivity Analysis | Individual model inputs (usually costs, utility values, and transition probabilities) are varied over large but biologically plausible ranges to determine the threshold at which model conclusions change. Frequently depicted as Tornado Diagrams. |
Probabilistic Sensitivity Analysis | Monte-Carlo simulations in which input values are simultaneously varied within pre-specified distributions bounded by ranges used for one-way sensitivity analyses. The number of simulations are usually between 1,000 and 100,000, and entire CEA is re-run for each simulation to produce estimates of the percent of simulations in which a given treatment was cost-effective. |
In summary, cost-effectiveness analyses offer the opportunity to quantify the costs, toxicity and oncologic benefit of NMIBC treatments, facilitating both an understanding of treatment tradeoffs and the comparison of novel agents to existing standards of care. Sensitivity analyses may further identify subsets of patients for whom a given treatment may be preferred, thereby enabling more personalized treatment recommendations. In this manner, CEA represents a tool to assist clinicians as well as guideline panels on interpreting data and individualizing options for NMIBC patients.
- Chang SS, Boorjian SA, Chou R et al: Diagnosis and treatment of non-muscle invasive bladder cancer: AUA/SUO Guideline. J Urol 2016; 196: 1021.
- Sanders GD, Neumann PJ, Basu A et al: Recommendations for conduct, methodological practices, and reporting of cost-effectiveness analyses: Second Panel on Cost- Effectiveness in Health and Medicine. JAMA 2016; 316: 1093.
- Khanna A, Yerram N, Zhu H et al: Utilization of bacillus Calmette-Guérin for nonmuscle invasive bladder cancer in an era of bacillus Calmette-Guérin supply shortages. Urology 2019; 124: 120.
- Sharma V, Wymer KM, Borah BJ et al: Cost-effectiveness of maintenance bacillus Calmette-Guérin for intermediate and high risk nonmuscle invasive bladder cancer. J Urol 2020; 204: 442.
- American Urological Association: BCG Shortage Info: Important Message About the BCG Shortage. Available at https://www.auanet.org/about-us/bcg-shortage-info. Accessed March 30, 2021.
- U.S. Food and Drug Administration: Bacillus Calmette-Guérin-Unresponsive Nonmuscle Invasive Bladder Cancer: Developing Drugs and Biologics for Treatment; Guidance for Industry; Availability. Federal Register 2018. Available at https://www.federalregister.gov/documents/2018/02/13/2018-02871/bacillus-calmette-gurin-unresponsive-nonmuscle-invasive-bladder-cancer-developing-drugs-and. Accessed March 30, 2021.
- Wymer KM, Sharma V, Saigal CS et al Cost-effectiveness analysis of pembrolizumab for bacillus Calmette-Guérin-unresponsive carcinoma in situ of the bladder. J Urol 2021; 205: 1326.
- Steinberg RL, Thomas LJ, Brooks N et al: Multi-institution evaluation of sequential gemcitabine and docetaxel as rescue therapy for nonmuscle invasive bladder cancer. J Urol 2020; 203: 902.
- Chang EM, Saigal CS and Raldow AC: Explaining health state utility assessment. JAMA 2020; 323: 1085.
- Neumann PJ and Cohen JT: QALYs in 2018–advantages and concerns. JAMA 2018; 319: 2473.