There is a significant and growing interest among both payers and producers of medical products for agreements that involve a "pay-for-performance" or "risk-sharing" element. These payment schemes-called "performance-based risk-sharing arrangements" (PBRSAs)-involve a plan by which the performance of the product is tracked in a defined patient population over a specified period of time and the amount or level of reimbursement is based on the health and cost outcomes achieved. There has always been considerable uncertainty at product launch about the ultimate real-world clinical and economic performance of new products, but this appears to have increased in recent years. PBRSAs represent one mechanism for reducing this uncertainty through greater investment in evidence collection while a technology is used within a health care system. The objective of this Task Force report was to set out the standards that should be applied to "good practices"-both research and operational-in the use of a PBRSA, encompassing questions around the desirability, design, implementation, and evaluation of such an arrangement. This report provides practical recommendations for the development and application of state-of-the-art methods to be used when considering, using, or reviewing PBRSAs. Key findings and recommendations include the following. Additional evidence collection is costly, and there are numerous barriers to establishing viable and cost-effective PBRSAs: negotiation, monitoring, and evaluation costs can be substantial. For good research practice in PBRSAs, it is critical to match the appropriate study and research design to the uncertainties being addressed. Good governance processes are also essential. The information generated as part of PBRSAs has public good aspects, bringing ethical and professional obligations, which need to be considered from a policy perspective. The societal desirability of a particular PBRSA is fundamentally an issue as to whether the cost of additional data collection is justified by the benefits of improved resource allocation decisions afforded by the additional evidence generated and the accompanying reduction in uncertainty. The ex post evaluation of a PBRSA should, however, be a multidimensional exercise that assesses many aspects, including not only the impact on long-term cost-effectiveness and whether appropriate evidence was generated but also process indicators, such as whether and how the evidence was used in coverage or reimbursement decisions, whether budget and time were appropriate, and whether the governance arrangements worked well. There is an important gap in the literature of structured ex post evaluation of PBRSAs. As an innovation in and of themselves, PBRSAs should also be evaluated from a long-run societal perspective in terms of their impact on dynamic efficiency (eliciting the optimal amount of innovation).

The task force emphasizes the need for precision and clarity in specifying the key policy questions to be addressed and that studies should be designed with a goal of drawing causal inferences whenever possible. If a study is being performed to support a policy decision, then it should be designed as hypothesis testing-this requires drafting a protocol as if subjects were to be randomized and that investigators clearly state the purpose or main hypotheses, define the treatment groups and outcomes, identify all measured and unmeasured confounders, and specify the primary analyses and required sample size. Separate from analytic and statistical approaches, study design choices may strengthen the ability to address potential biases and confounding in prospective observational studies. The use of inception cohorts, new user designs, multiple comparator groups, matching designs, and assessment of outcomes thought not to be impacted by the therapies being compared are several strategies that should be given strong consideration recognizing that there may be feasibility constraints. The reasoning behind all study design and analytic choices should be transparent and explained in study protocol. Execution of prospective observational studies is as important as their design and analysis in ensuring that results are valuable and relevant, especially capturing the target population of interest, having reasonably complete and nondifferential follow-up. Similar to the concept of the importance of declaring a prespecified hypothesis, we believe that the credibility of many prospective observational studies would be enhanced by their registration on appropriate publicly accessible sites (e.g., clinicaltrials.gov and encepp.eu) in advance of their execution.

This paper reviews the economic case for patents and the potential for differential pricing to increase affordability of on-patent drugs in developing countries while preserving incentives for innovation. Differential pricing, based on Ramsey pricing principles, is the second best efficient way of paying for the global joint costs of pharmaceutical R&D. Assuming demand elasticities are related to income, it would also be consistent with standard norms of equity.To achieve appropriate and sustainable price differences will require either that higher-income countries forego trying to "import" low drug prices from low-income countries, through parallel trade and external referencing, or that such practices become less feasible. The most promising approach that would prevent both parallel trade and external referencing is for payers/purchasers on behalf of developing countries to negotiate contracts with companies that include confidential rebates. With confidential rebates, final transactions prices to purchasers can differ across markets while manufacturers sell to distributors at uniform prices, thus eliminating opportunities for parallel trade and external referencing.

Key gaps in health economics and outcomes research best practices, decision standards, and value assessment processes are also discussed, along with next steps for evolving health economics and outcomes research practices in personalized medicine.

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