Why Comparing PBMs Is Extremely Difficult and How Structured Procurement Can Help

Comparing PBMs should not be as difficult as it often is.

Pharmacy Benefit Managers play a critical role in prescription drug benefits. They support pricing arrangements, pharmacy networks, formulary management, rebate administration, clinical programs, mail service, specialty pharmacy coordination, reporting, and implementation. For employer groups, consultants, brokers, and procurement teams, choosing the right PBM can have a major effect on cost, access, member experience, and administrative performance.

The challenge is that comparing PBMs is rarely straightforward.

PBM proposals often contain similar categories of information, but they do not always present that information in a consistent format. One proposal may provide a detailed explanation of rebate handling. Another may focus on financial guarantees. A third may emphasize clinical programs, specialty pharmacy capabilities, or network access. Even when the same questions are asked, the answers may use different definitions, assumptions, and levels of detail.

That does not mean PBMs are impossible to compare. It means the procurement process often makes comparison harder than it needs to be.

Why Comparing PBMs Usually Starts With Too Much Manual Work

Most PBM evaluations still begin with buyer initiated RFPs. These RFPs are often detailed, customized, and necessary for complex opportunities. But they also create a heavy comparison burden.

After responses come in, proposal teams, consultants, procurement leaders, and benefits advisors often have to normalize the information manually. They need to determine whether each PBM answered the same question, used the same assumptions, defined terms the same way, and included comparable financial and operational details.

This can turn PBM evaluation into a spreadsheet exercise.

Teams may need to manually compare:

• Pricing models
• Rebate structures
• Spread pricing arrangements
• Pass-through terms
• Retail pharmacy networks
• Specialty pharmacy models
• Mail service expectations
• Clinical programs
• Reporting capabilities
• Audit rights
• Performance guarantees
• Implementation timelines

These categories matter. A strong PBM comparison should include them. The problem is that they are often reviewed after the fact, once each PBM has already submitted a custom response.

That is an inefficient starting point.

PBM Pricing Is Not Always Apples to Apples

Pricing is one of the biggest reasons comparing PBMs becomes complicated.

A PBM proposal may include administrative fees, discounts, rebate guarantees, specialty pricing, mail service terms, and performance guarantees. It may also include assumptions about utilization, formulary structure, network participation, claims volume, or plan design.

Two PBMs may both appear competitive, but the comparison may change once the buyer looks more closely at definitions and assumptions.

For example, one proposal may emphasize rebate value. Another may offer stronger transparency. Another may show different pharmacy reimbursement terms. Another may reduce administrative fees but include different network or formulary tradeoffs.

Spread pricing can also complicate comparison. The Federal Trade Commission has continued to examine PBM pricing practices and pharmacy benefit market dynamics, including spread pricing and the role of large vertically integrated PBMs. That broader scrutiny has increased the importance of clear, structured PBM evaluation.

For buyers and advisors, the issue is not simply finding the lowest number. It is understanding what each number means.

Rebate Structures Require Careful Review

Rebates are another major source of complexity when comparing PBMs.

A buyer may need to understand whether rebates are passed through, retained, guaranteed, estimated, reconciled, or defined with specific exclusions. PBMs may structure rebate arrangements differently, and those differences can affect the overall economics of the contract.

The Department of Labor has proposed PBM fee disclosure requirements for providers of pharmacy benefit management services to employer-sponsored self-insured group health plans. The proposal focuses on disclosures that would help plan fiduciaries evaluate PBM service arrangements, compensation, and related financial information.  

That type of transparency pressure matters because it highlights a practical procurement challenge: more information does not automatically create easier comparison.

If rebate information arrives in inconsistent formats, buyers may still struggle to evaluate it efficiently. Transparency is most useful when the disclosed information is structured, comparable, and tied to clear definitions.

Networks, Specialty Pharmacy, and Mail Service Add More Variables

PBM comparison is not only financial.

A PBM’s pharmacy network can affect member access, convenience, disruption, and cost. Network fit may depend on geography, employee distribution, preferred pharmacy participation, independent pharmacy access, specialty pharmacy needs, and plan design.

Specialty pharmacy adds another layer. Specialty drug management may involve clinical support, prior authorization processes, adherence programs, reporting, distribution models, and patient support services. Buyers may need to understand what is included, what is optional, and how performance is measured.

Mail service also requires careful definition. Turnaround times may vary based on whether the prescription is new or a refill, whether the order is clean, whether prescriber clarification is needed, and when the measurement clock starts.

These details are not minor. They can affect service quality and member experience.

But when they are buried in narrative responses, comparing PBMs becomes harder than it needs to be.

Quality and Guarantees Are Hard to Standardize

Quality is one of the most important parts of PBM evaluation, but it can be one of the least standardized.

A PBM may define quality through claims accuracy, service levels, clinical outcomes, call center performance, implementation success, member satisfaction, reporting timeliness, or audit performance. All of those may be relevant, but they are not interchangeable.

Guarantees can also be difficult to compare. A guarantee is only meaningful if the buyer understands what is being guaranteed, how it is measured, what exclusions apply, and what remedy exists if performance is missed.

This is why comparing PBMs requires more than reading proposal language. It requires structured review.

The more consistent the evaluation fields are, the easier it becomes for human decision makers to focus on the real tradeoffs instead of spending time untangling formats.

PfRs Can Reduce the Complexity of Comparing PBMs

PfRs, or Proposals for Requestors, offer a structured alternative for early-stage PBM discovery and comparison.

A PfR is a vendor initiated procurement method designed to make structured business offerings available to qualified buyers through a controlled online marketplace. In a PBM context, a PfR can help vendors present available offerings using standardized templates that cover key comparison categories such as pricing model, rebate structure, network type, specialty pharmacy, mail service, clinical programs, implementation timeline, reporting, and guarantees.

PfRs are not public sales collateral. They are not buyer initiated. They are not tailored to one specific buyer. They are marketplace based offerings that become discoverable only after access requirements are met.

For buyers, this creates a better starting point for comparing PBMs. Instead of waiting for several custom RFP responses to arrive and then trying to normalize the information, buyers can begin with structured offering data.

For PBMs, it can reduce repetitive early-stage response work. A vendor can present an offering in a standardized way, control access, and allow qualified buyers to understand whether the fit is worth deeper discussion.

This does not eliminate custom procurement. It does not remove the need for consultants, legal review, clinical evaluation, or negotiation. It simply makes the early comparison process more structured.

AI Can Help, But Only After the Data Is Organized

AI can support PBM comparison, but it should not be treated as a magic solution.

AI tools can help summarize differences, identify missing information, compare structured fields, and support human decision making. But AI is most useful when the underlying data is organized.

If PBM proposals arrive in inconsistent formats with different assumptions and undefined terms, AI may help with summarization, but it cannot fully solve the comparison problem. Standardized templates make AI assistance more practical because they give the system cleaner fields to evaluate.

The better sequence is simple:

First, structure the data.
Then, compare the offerings.
Then, use AI to support faster human review.

That is a realistic role for AI in PBM procurement.

Comparing PBMs Should Be More Structured, Not Less Rigorous

PBM procurement should remain rigorous.

The stakes are too high for oversimplified selection. Prescription drug benefits affect cost, access, member satisfaction, pharmacy relationships, specialty drug strategy, and employer financial performance.

But rigor does not have to mean unnecessary friction.

Comparing PBMs becomes easier when the information is organized around consistent categories. Pricing should be compared against pricing. Rebates should be compared against rebates. Networks should be compared against networks. Guarantees should be compared against guarantees. Clinical programs should be reviewed in a structure that helps buyers understand what is actually being offered.

That is the practical opportunity behind structured procurement.

The goal is not to make PBM evaluation casual. The goal is to make it clearer.

When PBMs are easier to compare, buyers can make better decisions, consultants can focus on higher-value analysis, and proposal teams can spend less time reformatting the same core information across different RFPs.

Comparing PBMs does not need to be difficult by default. It becomes difficult when the procurement process starts with unstructured documents and tries to create comparison later.

A better process starts with structure.

For additional background on the role PBMs play in rebates, pharmacy networks, formularies, specialty pharmacy, and mail-order services, the Commonwealth Fund offers a helpful overview of how PBMs contribute to prescription drug spending.

For a deeper look at why PBM procurement is fundamentally a comparison problem, read Rapid Request’s article on PBM procurement and comparison workflows.