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When cost savings aren't really savings: the hidden economics of non-medical switching in ankylosing spondylitis

Erik Abel, PharmD, MBA · January 19, 2026 · 7 min read

As PBMs, payers, employers, and health systems increasingly adopt biosimilars to manage costs, it is critical to distinguish between two fundamentally different patient populations, treatment-naive patients and stable patients on established therapy. While many biologic agents, both originators and biosimilars, are used across autoimmune diseases, ankylosing spondylitis (AS or SpA) presents unique risks when disease control is disrupted. AS is a chronic autoimmune disorder that primarily affects the spine and sacroiliac joints, causing progressive pain, stiffness, and structural damage. Loss of control can result in irreversible spinal or hip fusion, severe chronic pain, and permanent, life-altering mobility impairment.

This issue is not academic for me.

I have ankylosing spondylitis and have been clinically stable on Humira (adalimumab) for three-plus years, a stability achieved through evidence-based care that has changed my life, thanks to Brian Horgan, PA-C and AHN Rheumatology. Yet despite sustained disease control, I continue to face pressure to switch therapies from PBMs for non-medical reasons, reinforcing why advocacy grounded in clinical evidence matters for patients beyond my own experience.

What the evidence and guidelines say

The 2019 American College of Rheumatology (ACR), Spondylitis Association of America (SAA), and Spondyloarthritis Research and Treatment Network (SPARTAN) guidelines provide a strong recommendation against mandated non-medical switching from originator TNF inhibitors to biosimilars in patients with stable ankylosing spondylitis.1 This is not about biosimilar efficacy. It is about the clinical risks of non-medical switching in patients who have achieved disease control.

What the data shows

  • The ABILITY-3 trial showed 53% of patients who discontinue Humira (adalimumab) experience disease flare, and critically, 44% never regain disease remission upon retreatment. This is a real risk if the biosimilar is ineffective.2
  • Real-world studies demonstrate that non-medical switching is associated with reduced remission rates from 92.7% to 80.9%,3 with some biosimilars showing 12-month drug survival rates as low as 73% compared to 90% for others.4
  • Non-medical switching increases total healthcare costs by roughly $4,000 per patient per year, with healthcare resource utilization rising 4% to 37% post-switch,5,6 potentially offsetting any drug cost savings.
  • Moreover, 80% of AS costs are work-related productivity losses. Disease flares drive disability and employee absenteeism, not just medical expenses.7

The right approach

  • Biosimilars as first-line therapy in treatment-naive patients, supported by comparable efficacy data.
  • Biosimilars after treatment failure or intolerance, an appropriate clinical indication with viable opportunity.
  • Mandated switching in stable patients introduces unnecessary clinical risk without clear benefit and risks breaking what is already fixed.

A call for attention from the stakeholders

The goal should be sustainable cost management, not short-term drug cost reduction that increases downstream utilization. Shared decision-making between physicians and patients, not administrative mandates, should guide treatment decisions in stable patients.

  • PBMs. Express Scripts, CVS Caremark, Optum Rx, Prime Therapeutics.
  • Specialty pharmacies. CVS Specialty, Walgreens Boots Alliance, Optum Specialty Pharmacy, Accredo Specialty Pharmacy, Amber Specialty Pharmacy, Avella Specialty Pharmacy, Senderra Specialty Pharmacy.
  • Manufacturers. AbbVie, Amgen, Samsung Bioepis, Sandoz, Boehringer Ingelheim, Pfizer, Coherus BioSciences, Organon, Mark Cuban Cost Plus Drug Company.

I would like to give special commendation and recognition to Rightway Healthcare and Jordan Feldman, who are leading new disruptive PBM approaches and recognized a unique path forward with an exception in this disease state in their biosimilar strategy.

Evidence-based formulary design should recognize that

  • Treatment-naive patients are ideal candidates for biosimilar initiation.
  • Stable patients on originator biologics face real clinical risks from non-medical switching.
  • Total cost of care includes flares, work disability, and healthcare resource utilization.

The majority of U.S. physicians (84%) oppose non-medical switching in stable patients, with concerns about treatment efficacy (57%), patient safety (53%), and mental health impacts (59%), especially in AS and SpA.8

Let us align payer and PBM policy with clinical evidence and guidelines. Biosimilars have an important role in healthcare, but that role should be defined by medical appropriateness, not blanket switching mandates in the absence of the full economic picture.

Key references

All views, analyses, and services presented here reflect my independent professional perspective, informed by more than two decades of real-world experience, and do not represent the views or positions of any current or former employer or affiliated organization.

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