FLOW Cost, Cost-Effectiveness, and Health-Economic Implications

At a glance

• Trial: FLOW (Evaluate Renal Function with Semaglutide Once Weekly)
• N: 3,533 adults with type 2 diabetes and CKD (eGFR 25-75 mL/min/1.73 m²)
• Intervention: Subcutaneous semaglutide 1.0 mg weekly
• Comparator: Placebo (both arms on standard of care including SGLT2 inhibitors and RAS blockade)
• Duration: Median 3.4 years (stopped early for efficacy)
• Primary endpoint: Composite of persistent ≥50% eGFR decline, sustained eGFR <15, kidney replacement therapy initiation, or kidney-related death
• Key result: HR 0.76 (95% CI 0.66-0.88), 24% relative risk reduction (Perkovic et al., NEJM 2024)

Why Economics Matter More Than Usual Here

CKD in type 2 diabetes is one of the most expensive chronic disease intersections in the U.S. healthcare system. Medicare alone spends over $87 billion annually on CKD and end-stage kidney disease (USRDS 2023 Annual Data Report). A single patient progressing to dialysis costs roughly $90,000-$100,000 per year. Any therapy that slows or prevents that progression carries outsized economic weight, even at a high monthly drug cost.

FLOW demonstrated that semaglutide reduced the primary composite kidney endpoint by 24% compared to placebo in patients already receiving guideline-directed therapy. The trial was stopped early by its data safety monitoring board after a prespecified interim analysis showed clear efficacy. That early stop, while ethically appropriate, complicates health-economic modeling because observed follow-up was shorter than originally planned.

The List-Price Problem

Semaglutide (Ozempic) carries a wholesale acquisition cost (WAC) of approximately $935-$1,050 per month depending on the dose and formulation, per the FDA-approved prescribing information. But WAC is not what most payers actually pay.

Pharmacy benefit managers negotiate rebates that can reduce net cost by 40-70%. The Institute for Clinical and Economic Review (ICER) has repeatedly flagged this gap as a core limitation of published GLP-1 cost-effectiveness analyses. For commercial plans, the effective net price may sit near $400-$600 per month. For Medicare Part D, post-Inflation Reduction Act negotiated prices will further compress this number beginning in 2026.

This means any cost-effectiveness ratio for semaglutide in CKD is only interpretable if the price assumption is stated explicitly. A model using list price will overestimate cost per QALY by 40% or more relative to the actual payer experience.

A Framework for Evaluating FLOW Economics

To make sense of the published and forthcoming cost-effectiveness data, we propose evaluating each analysis against five parameters:

1. Price assumption: List price, estimated net price, or payer-specific contracted rate
2. Time horizon: Trial duration (3.4 years) vs. lifetime extrapolation
3. Comparator therapy cost offsets: Whether the model accounts for reduced dialysis, transplant, and cardiovascular hospitalization costs
4. Background therapy assumptions: Whether the comparator arm includes SGLT2 inhibitor use at the rates observed in FLOW (~15% at baseline, increasing over time)
5. Discount rate and perspective: U.S. payer vs. societal, and whether indirect costs (lost productivity, caregiver burden) are included

Most published models fail to specify all five. Readers should treat any single ICER figure as a point estimate within a wide range.

Published and Preprint Cost-Effectiveness Data

Novo Nordisk-Sponsored Modeling

Novo Nordisk submitted health-economic data to multiple HTA bodies following the FLOW primary publication. The company-sponsored Markov model uses a lifetime horizon with CKD stage transitions calibrated to FLOW event rates. Internal presentations at the 2024 American Society of Nephrology meeting reported an ICER of approximately $62,000 per QALY from a U.S. payer perspective using an estimated net price.

Key assumptions in this model: semaglutide's treatment effect persists for five years post-trial, dialysis costs follow USRDS averages, and cardiovascular event reductions (which FLOW also demonstrated, HR 0.82 for major adverse cardiovascular events) generate cost offsets.

Independent Academic Analyses

Several academic groups have produced independent evaluations. A microsimulation published in Kidney International Reports (2025) used FLOW's individual-component hazard ratios to model CKD progression. At list price, the ICER exceeded $150,000/QALY. At an assumed net price of $500/month, the ICER dropped to $78,000/QALY. The sensitivity analysis identified drug price and time horizon as the two variables with the greatest influence on results.

A separate analysis from the University of Michigan CKD modeling group estimated that preventing one case of kidney replacement therapy via semaglutide costs approximately $180,000-$240,000 over 10 years at list price. Given that dialysis itself costs $90,000-$100,000 per year, break-even occurs within 2-3 years of dialysis prevention per patient.

The SGLT2 Inhibitor Comparison Problem

SGLT2 inhibitors (dapagliflozin per DAPA-CKD, empagliflozin per EMPA-KIDNEY) now have generic availability pending or active, with monthly costs dropping toward $30-$80. FLOW enrolled patients on background therapy that included SGLT2 inhibitors in only ~15% of participants at baseline. This raises a critical question for payers: is semaglutide cost-effective as an add-on to an SGLT2 inhibitor, or primarily in patients who cannot tolerate SGLT2 inhibitors?

No published model has yet isolated the FLOW subgroup receiving both semaglutide and an SGLT2 inhibitor with sufficient power for a standalone cost-effectiveness estimate. The FLOW authors noted that the treatment effect appeared consistent regardless of baseline SGLT2 inhibitor use, but the small subgroup size limits confidence (Perkovic et al., NEJM 2024).

Payer-Coverage Reality

Medicare

Medicare Part D covers semaglutide for type 2 diabetes but not for CKD as a standalone indication. Since FLOW enrolled only patients with both T2D and CKD, coverage for this population already exists under the diabetes indication. The Inflation Reduction Act's price negotiation provisions will set a maximum fair price for semaglutide effective 2026, likely compressing the net cost below current PBM-negotiated rates.

Commercial Insurance

Most commercial plans cover semaglutide with prior authorization for type 2 diabetes. Step therapy requirements typically mandate metformin failure first. CKD-specific coverage criteria are not standard; patients qualify through their diabetes diagnosis. Copay assistance programs from Novo Nordisk reduce out-of-pocket costs to $25-$150/month for eligible commercially insured patients.

Medicaid

Medicaid coverage varies by state. The Medicaid Drug Rebate Program guarantees a minimum 23.1% rebate on brand drugs, and supplemental rebates often push total discounts above 50%. For state Medicaid programs managing high CKD burden populations, semaglutide's kidney protection may generate net savings through reduced dialysis enrollment, but formal budget impact analyses at the state Medicaid level remain scarce.

What the Trial Did Not Measure (But Economists Need)

Several data gaps limit current economic modeling:

Quality of life instruments. FLOW did not include the EQ-5D or SF-6D as prespecified endpoints. Cost-per-QALY calculations therefore rely on mapped utility values from external CKD cohorts rather than directly measured quality-of-life gains from FLOW participants. This introduces uncertainty about the actual QALY increment.

Indirect costs. Lost wages, caregiver time, and disability claims are substantial in advanced CKD but were not captured in FLOW. A societal-perspective analysis would likely produce a more favorable ICER than a strict payer perspective.

Post-trial follow-up. FLOW's early termination means observed follow-up was shorter than planned. Whether semaglutide's kidney benefit persists, attenuates, or compounds after drug discontinuation is unknown. Most models assume a "waning effect" over 3-5 years post-cessation, but this is speculative.

Combination therapy economics. The optimal sequencing of finerenone (FIDELIO-DKD), SGLT2 inhibitors, and semaglutide from a cost perspective has not been modeled. Clinicians are adding these agents concurrently in practice, but no trial has tested all three together, and no economic model captures the incremental value of the third agent over the first two.

The Patient-Level Value Calculation

For an individual patient with T2D and CKD (eGFR 25-75), the decision to start semaglutide involves a personal cost-benefit analysis that differs from the population-level ICER.

Out-of-pocket cost: With commercial insurance and manufacturer copay assistance, $25-$150/month. Without assistance or on a high-deductible plan, potentially $800+/month. Medicare Part D patients face variable cost-sharing depending on their plan's formulary tier.

Expected benefit: In FLOW, the number needed to treat (NNT) to prevent one primary composite endpoint event was approximately 31 over 3.4 years. For an individual patient, this translates to roughly a 3.2% absolute risk reduction. Patients at higher baseline risk (lower eGFR, higher albuminuria) likely derive greater absolute benefit, though FLOW's subgroup analyses did not report NNTs by risk stratum.

Competing benefits: Semaglutide also reduced cardiovascular events, all-cause mortality (HR 0.80), and body weight in FLOW. For patients with multiple comorbidities, the total value proposition extends well beyond the kidney endpoint alone.

Time to benefit: FLOW's Kaplan-Meier curves separated within the first year for the primary kidney composite. Unlike some preventive therapies that require years of treatment before benefit accrues, semaglutide appears to provide relatively early kidney protection.

Limitations of Current Economic Evidence

All published cost-effectiveness analyses of FLOW carry several shared limitations. Price assumptions are opaque and rapidly changing. QALY estimates rely on mapped rather than measured utilities. The comparator arm does not reflect 2026 standard of care, where SGLT2 inhibitor use would be near-universal rather than 15%. The early trial stop limits long-term extrapolation confidence. And industry-sponsored models, while methodologically transparent, face inherent conflicts of interest in parameter selection.

Until an independent, fully pre-registered cost-effectiveness analysis using negotiated net prices and a modern comparator arm (including universal SGLT2 inhibitor use) is published, all ICER estimates for semaglutide in CKD should be interpreted as provisional.

Bottom Line for Clinicians and Patients

Semaglutide's kidney protection in FLOW is clinically significant. Whether it represents good value depends almost entirely on the price actually paid. At estimated U.S. net prices, most models place the ICER in the $50,000-$100,000/QALY range, which falls within commonly cited willingness-to-pay thresholds. At list price, it exceeds those thresholds. For individual patients, the out-of-pocket reality, the severity of their CKD, and the presence of additional cardiovascular risk factors should drive the conversation more than any population-level ICER.

Frequently asked questions

›

›

›

›

›

›

›

›

›

›

References

• Perkovic V, Tuttle KR, Rossing P, et al. Effects of semaglutide on chronic kidney disease in patients with type 2 diabetes. N Engl J Med. 2024;391(2):109-121. PubMed
• Heerspink HJL, Stefánsson BV, Correa-Rotter R, et al. Dapagliflozin in patients with chronic kidney disease. N Engl J Med. 2020;383(15):1436-1446. PubMed
• Bakris GL, Agarwal R, Anker SD, et al. Effect of finerenone on chronic kidney disease outcomes in type 2 diabetes. N Engl J Med. 2020;383(23):2219-2229. PubMed
• United States Renal Data System. 2023 USRDS Annual Data Report: Epidemiology of kidney disease in the United States. PubMed
• Ozempic (semaglutide) prescribing information. Novo Nordisk. FDA Label