A larger rebate guarantee from a pharmacy benefit manager (PBM) does not mean a self-funded employer's pharmacy costs are falling, and with GLP-1 and specialty drug utilization growing sharply, the gap between the two measures is widening in ways that are becoming harder to ignore at renewal time.
That is the core warning from Paul Pruitt, chief growth officer and co-founder of SHARx, a high-cost prescription drug procurement platform, whose analysis lands as employers head into 2027 benefit renewals with pharmacy now representing 25% of total healthcare spending.
Employer drug costs are projected to rise 12% in 2026, outpacing overall healthcare trend, driven by GLP-1 growth, expanding specialty drug indications, and emerging cell and gene therapies, according to Business Group on Health's 2027 Employer Healthcare Strategy Survey.
Consider an employer with 100 members on a high-cost therapy at $10,000 per person annually - $1 million in total spend. A negotiated 10% price reduction looks like meaningful savings. But if utilization grows to 140 members, total spend rises to $1.26 million, a 26% increase despite the lower unit cost. The discount offset the price but not the volume, and the budget still grew.
For Pruitt, that gap between unit-cost savings and total spend is the central flaw in how most employers evaluate pharmacy performance. "CFOs should focus on the total pharmacy spend, not the savings percentage printed in the contract," he said.
The hypothetical holds up against the data. Research published in the American Journal of Managed Care found that nearly two-thirds of employers with self-funded pharmacy benefits reported specialty drug rebate agreements that include a rebate guarantee. The study raised concern that the prevalence of such arrangements may obscure employer visibility into actual net drug prices, potentially steering formularies toward higher-cost products and lifting total pharmacy costs overall.
Utilization, not unit cost, is now the primary driver of specialty drug spend. Pharmaceutical Strategies Group's 2026 State of Specialty Spend and Trend Report found net specialty drug costs rose 12.5% in 2025, with the share of members using at least one specialty drug climbing from 4.4% in 2023 to 5.5%. Growth was driven by member penetration and new drug indications, rather escalating cost per claim. That is the dynamic SHARx describes. More people are using expensive therapies, at more points in their treatment, for longer.
PBM contracts typically show rebate guarantees, generic fill rates, and prescription discounts. What they don't show is who is entering therapy, at what rate, and how utilization will shift over a plan year. Pruitt's recommendation is to model GLP-1s, specialty medications, oncology therapies, autoimmune treatments, and high-cost infusions as separate budget lines, tracking new-to-therapy rates, continuation and persistence rates, and pipeline therapies approaching coverage eligibility.
That kind of forecasting has become more urgent as PBM relationships themselves face scrutiny. A National Alliance of Healthcare Purchaser Coalitions survey of 408 employers, published in August 2026, found the share using a PBM outside the traditional big three - CVS Caremark, Optum Rx, and Express Scripts - rose from 37% in 2025 to 46%, with more than half of employers still on the big three considering a switch.
Separately, Business Group on Health found that 32% of employers plan to offer transparent or new-generation PBM models - arrangements that pass rebates directly to plan sponsors and disclose net drug costs - in 2027, with another 47% weighing the move for 2028 to 2029.
Pruitt is careful to draw a line between cost control and access restriction. Blunt coverage restrictions, he argues, create employee complaints, absenteeism, and eroded trust in the benefit, shifting costs rather than resolving them. "The objective is sustainable access, not indiscriminate approval or denial," he said. A responsible pharmacy strategy, he notes, combines clinical guidelines, appropriate utilization management, patient advocacy, and support programs that improve adherence.
As pharmacy spend grows faster than overall healthcare trend, the metrics in most PBM performance reports are measuring the wrong thing heading into another year of double-digit cost projections.
