Independent Market Access and Reimbursement Risk Assessment.

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Tirzepatide for managing overweight and obesity

As of September 2025, MARA’s assessment finds Tirzepatide’s reimbursement risk concentrated in resource use and cost implications, with comparator selection a strength; the current MARA Rating and full rationale are available in the report.

The assessment also weighs care pathway integration: how the drug fits into the way care is organised today; a treatment that demands new infrastructure or displaces an established pathway faces extra scrutiny. The strength recorded in comparator selection carries weight because that domain asks whether the drug was tested against the treatment payers actually fund today; a benefit shown against the wrong comparator carries little weight in a reimbursement decision.

Obesity

This rating sits within MARA’s Obesity coverage, alongside 8 other independently assessed treatments in the same area.

What payers will ask

Is the clinical benefit the kind payers reward? — Clinical effectiveness

The clinical evidence from the SURMOUNT-1 trial demonstrates that tirzepatide significantly reduces body weight compared to placebo, with a mean percentage change of -20.1% and a high percentage of patients achieving at least 5% weight loss (96.3% vs. 27.9% for placebo). This indicates a clear clinical advantage over standard care, although the long-term effects beyond 72 weeks remain uncertain.

Does the economic case hold at the expected price? — Cost effectiveness

The ICER for tirzepatide in the target population is above the acceptable threshold of £20,000 per QALY gained, with estimates around £28,697 to £29,810. This indicates low cost-effectiveness, necessitating further justification for its price relative to the benefits provided.

Is there quality-of-life evidence payers weigh? — Quality of life

While specific HRQoL data is not extensively detailed, the evidence suggests that tirzepatide improves quality of life through significant weight loss, which is likely to enhance daily functioning and well-being. However, the evidence is primarily based on weight loss outcomes rather than direct HRQoL measures.

Does the safety profile hold up for payers? — Safety and Adverse Effects

Tirzepatide has a favorable safety profile, with most adverse events being mild to moderate. The trial data indicate that serious adverse events are rare, supporting a very good tolerability compared to existing therapies.

Was the drug compared against what payers expect? — Comparator Selection

The comparators used in the trials, including semaglutide and diet/exercise support, are appropriate and reflect current treatment standards for obesity management. The evidence supports the relevance of these comparators in assessing tirzepatide’s effectiveness.

Is the population defined the way payers need it? — Patient Population and Subgroups

The trial population is broadly representative of the intended patient population, including those with relevant comorbidities. However, the exclusion of individuals with type 2 diabetes raises some concerns about generalizability.

Does the drug fit how care is delivered and paid for? — Care Pathway Integration

Integrating tirzepatide into existing care pathways will require significant adjustments, particularly in ensuring adequate diet and exercise support, which may not be uniformly available across primary care settings.

Are the wider system costs understood? — Resource Use and Cost Implications

The anticipated budget impact of tirzepatide is significant, with estimates exceeding £20 million in the first three years. This raises concerns about the sustainability of its implementation within the NHS.

Would the evidence survive payer scrutiny? — Evidence Quality and Robustness

The evidence base is strong, supported by a well-conducted Phase 3 trial (SURMOUNT-1) with a large sample size and robust methodology. However, some uncertainties remain regarding long-term outcomes.

How exposed is the case to uncertainty? — Uncertainty, Sensitivity, and Broader Impacts

There are notable uncertainties regarding the long-term effectiveness of tirzepatide and its broader impacts on health outcomes, particularly in populations excluded from the trials. This uncertainty may affect decision-making.
This rating replaces the earlier December 2024 rating of the same drug and indication — still on the record here.

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