Merck Data Discredits PBM-Sponsored Study of Brand Drug Price Inflation


We present data supplied by the drug company Merck that discredits a study sponsored by the pharmacy benefit manager (PBM) trade association showing no correlation between PBM rebate rates and brand drug price inflation.


The management of the prescription (Rx) drug benefit portion of health care plans has become the domain of contracted specialists called pharmacy benefit managers (PBMs).

The three largest, independent PBMs — Express Scripts, CVS Health,  and Optum Rx, (known as “The Big 3”) control 73% of the total Rx claims processed the United States in 2015.

Since the early 2000s, PBMs have continually come under attack for not acting in the best interest of their clients.  We have written a number of papers since 2004 pinpointing an opaque reseller business model as the source of this misalignment.

In a 2017 paper, we have presented the case that there have been 3 distinct phases of the PBM business model over the past 15 years demarcated by radical shifts in the primary source of gross profits:

  1. up to 2005 — reliance on retained rebates from small molecule brand drugs;  
  2. 2005 – 2010 — reliance on mail order generics Rx margins;
  3. 2010 – today — reliance on retained rebates from specialty drugs.

To compensate for declining mail order generics Rx margins after 2010, PBMs saw the rising trend of specialty and biotech drugs as a promising basis for a renewed reliance on retained rebates.

But there are several constraints today on this phase of the PBM business model.

The first constraint in that the specialty drug Rx volume “basis” for collecting rebates today is a lot less than it was ten years ago when small molecule drugs were the basis for rebates.

The second constraint is a newfound awareness by clients of PBMs that retained rebate dollars can be substantial yet an opaque source of PBM gross profits.   As a defensive move, CVS Health finally declared publicly on their website that,

“CVS Caremark was able to reduce trend for clients through… negotiations of rebates, of which more than 90 percent are passed back to clients.”

The problem facing PBMs today is how to derive a majority of gross profits from specialty Rx while maintaining a transparent rebate retention rate at 10% on average.

In order to show how PBMs can overcome these constraints,  we have deconstructed data supplied by the drug company Merck (see below) that depicts a growing a divergence between their list prices for brand drugs (gross) and the prices they receive after deductions of rebates paid to PBMs (net).

This growing divergence has come to be known as   “gross-to-net rebate bubble”   Other drug companies are publishing similar data as a way of defending themselves against charges of double-digit price-gouging tactics.

This is a graphic depiction of Merck’s gross-to-net price bubble:

Our deconstruction of the Merck data lays out a step-by-step sequence of how PBMs and drug companies might negotiate the parameters of a rebate deal today under the constraint that PBMs have to grow gross profit DOLLARS over time while fixing the rebate retention rate at 10%.

We can use the same Merck-supplied data to plot annual % increases in list prices (line 1 above) against the annual negotiated rebates and discounts as a % of the list prices (line 3 above).  The result shows a significant positive correlation coefficient ratio of .653

PBMs Under Attack for Causing Drug Price Inflation

In January, 2017 newly elected President Donald Trump attacked drug companies in press conference for “getting away with murder” by raising drug prices at double-digit rates in recent years.

Since the Trump rant,  there have been articles in the New York Time, the Los Angeles Times and other publication where both retail pharmacists and drug companies are quoted as saying it is PBMs that drive drug price inflation.  Here is a quote from the New York Time article,

“Want to reduce prescription drug costs?” the pharmacists argued during their visits. “Pay attention to the middlemen.”

The PBM-Sponsored Study

The PBM trade group association Pharmaceutical Care Management Association (PCMA) commissioned a study by the health care consulting company Visante to provide data relevant to the issue of the causes of recent drug price inflation.  

In April 2017, the PCMA announced in a press release that results of the Visante study were available on-line.  The key result:

“There is no correlation between the prices drug companies set and the rebates they negotiate with PBMs”

The press release also provided a quote by PCMA President and CEO Mark Merritt:

“This study debunks the notion that the prices drugmakers set are contingent on the rebates they negotiate with PBMs…”

Below is a screenshot of the graph depicting the finding of “no correlation”

Reconciling Differences in Results: A Question of Sample Chosen

The Merck data shows a significant positive correlation between annual brand drug list price inflation and annual rebates rates that Merck has negotiated with PBMs.  The PBM-sponsored study shows no correlation.

Obviously, a key reconciling difference revolves around the sample chosen.  

The Merck results are heavily weighted by three brand drugs.  Merck has reported In its 2017 annual 10-K report that about one-third of its drug sales comes from three brand drugs: (1) the diabetes drug Januvia; (2) the cholesterol drug combinations Zetia/Vytorin; and (3) the cervical cancer prevention vaccine Gardasil.  

In terms of rank among the top 200 selling brand drugs, Januvia ranked #19, Zetia #38, and Gardasil #56 according to a 2015 listing.

Each of these drugs are what we call highly “rebatable” — in therapeutic classes where there are a number of other brand that are therapeutically equivalent.  

Merck competes vigorously with other drug companies for preferred status on formularies which list drugs approved by PBMs for coverage.  Competition insures that winning bids are high for placement in these therapeutic classes.  Merck has to “pay to play” and covers higher and higher rebate percentages paid to PBMs with list price inflation.

To achieve such high rankings,  it means that Merck must be winning placement for its top selling drugs with each of the Big 3 PBMs who control collectively 73% of the market.

While Merck’s sample size is small compared to the PBM-sponsored study, Merck’s data represents the essence of what has been going on between Pharma and Big 3 PBMs since 2010.

The sample size of the PBM-sponsored study is much larger. It contained a

“sample of the top 200 self-administered, patent protected, brand-name drugs, 24 drugs were excluded because of incomplete data for the study time period, leaving a remaining sample of 176 drugs for analysis”.

First, the initial sample size of 176 was aggregated in 23 therapeutic classes with the averages used in plots.  No mention is made as to whether the 23 data points represent simple or averages weighted by revenue.  In any case, samples of averages smooth out differences in the raw data.

Second, the larger sample size could contain significant number of drugs that just are not “rebatable” — in “aging” therapeutic classes with a 4+ brand drugs that are therapeutically equivalent (“me-too drugs”) plus a number of off-patent, low cost generic drugs.

In short, we believe that the sample used in the PBM-sponsored study is a smoothed-out representation of the outcomes of negotiations between drug companies with “rebatable” brand drugs and the Big 3 PBMs.


Published by Lawrence W. Abrams

Economist, Ph.D. WashU StL, B.A Amherst. I write at the intersection of economics, finance, accounting and high tech. I have been a critic of PBMs since 2003. I have received no remuneration writing these papers.

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