With the 2026 revisions shaping the landscape of healthcare policy, I felt the need to map out the current state of Japan’s HTA system. As someone working at the intersection of data and policy, this guide is my attempt to clarify how we measure “value” in modern medicine.
Introduction: The Concept of “Value for Money” in Medicine
Japan has a universal healthcare system that provides high-quality medical care to everyone. However, many ultra-high-cost drugs—like new cancer therapies and gene treatments—are appearing now. This makes it difficult to keep the national health insurance budget sustainable.
Therefore, Japan started the Health Technology Assessment (HTA) system in April 2019. The goal is to check “Value for Money.” The system ensures that the price of a drug matches the clinical benefit it gives to patients and the healthcare system.
Chapter 1. Japan’s Unique “Post-Reimbursement” Model
The Japanese HTA system is structurally different from many other countries.
1. Price Adjustment Instead of a Gatekeeper
In some countries like the UK, if a drug gets a negative HTA result, the insurance will not cover it. Japan is different. Japan puts patient access first. Therefore, almost all approved drugs get insurance coverage first. The government uses HTA as a “complementary tool” to adjust the drug’s price (up or down) after it is already on the market.
2. The Core Metrics: QALY and ICER
To measure “value” scientifically, Japan uses two main international metrics:
- QALY (Quality-Adjusted Life Year): This measures both the length of life (survival) and the quality of life (QOL). One QALY means one year of life in perfect health.
- ICER (Incremental Cost-Effectiveness Ratio): This formula calculates the extra cost needed to get one extra QALY compared to existing standard treatments (the chosen comparator, standard of care).
ICER = \frac{\text{Cost (New Drug)} – \text{Cost (Existing Treatment)}}{\text{Effect (New Drug)} – \text{Effect (Existing Treatment)}}
3. Thresholds for Value
In Japan, if the ICER is below 5 million yen per QALY, the drug is “cost-effective.” The government keeps its price. For cancer or rare diseases, the threshold increases to 7.5 million yen per QALY because these patients have high unmet needs.
Chapter 2. The 2026 (Reiwa 8) Reform: A New Era for HTA
The April 2026 reform updates how Japan evaluates drug costs. The evaluations are becoming more strict and dynamic.
1. The New Price Adjustment Formula
If a new drug does not show an additional benefit compared to existing treatments, the government uses a new formula. This formula matches the new drug’s price closer to the existing treatment’s price (the comparator price).
- New Formula:
\text{Adjusted Price} = \text{Pre-adjusted Price} \times \frac{\text{Comparator Daily Drug Price}}{\text{Target Daily Drug Price}} - 15% Reduction Cap: A very big price drop can make drug supply unstable. Therefore, the maximum price cut from this HTA formula is limited to 15% (the price will not go below 85% of the original price).
2. Dynamic Re-Evaluation (H3 Category)
HTA is not a one-time check at the start. Under the 2026 rules, the government can evaluate a drug again (under category H3) even after the first review is finished. This happens if there is important new clinical data or new global HTA results.
3. Terminology and Caregiving Costs
The government changed the term “Additional Benefit” to “Improvement in health outcome indicators relative to the comparator.” This avoids confusion with other drug pricing rules. Also, the 2026 rules give clearer instructions on how to include caregiving costs. This recognizes that good drugs can reduce the burden on family members.
4. Implementation Schedule
For drugs that report HTA results after April 2026, the price adjustments will wait until September 2026. This gives the government time to check the technical effects of the new reform before changing prices.
Chapter 3. Selection Criteria: The “H-Category” Framework
Not all medicines go through HTA. The government selects drugs based on their impact on the national health budget using five categories.
| Category | Timing | Main Criteria |
| H1 | At Listing | High-budget drugs (predicted peak sales >50 billion yen). |
| H2 | At Listing | Predicted peak sales >10 billion yen and high innovation premiums. |
| H3 | Post-Listing | Expanding products with sales over 5 billion yen, or re-designated items. |
| H4 | Legacy | Large-market drugs listed before the 2019 policy started. |
| H5 | Similarity | Follow-on drugs adjusted based on the result of a similar representative drug. |
Exemptions: Drugs for ultra-rare diseases (designated intractable diseases) or pediatric conditions usually do not go through HTA. This ensures patients can get essential treatments quickly.
Chapter 4. Technical Guidelines for Analysis
The C2H (Center for Outcomes Research and Economic Evaluation for Health) checks the technical quality of the data.
- EQ-5D-5L Standard: Japan prefers to measure quality of life (QOL) using the EQ-5D-5L tool. Companies can convert other scales (“mapping”), but review committees check this very strictly because it introduces uncertainty.
- Perspective: The analysis must use the “Public Payer Perspective.” This includes public insurance costs and patient co-payments.
- Discounting: Future costs and health effects decrease by 2.0% per year to calculate their value today.
Chapter 5. International Comparison: 2026 Global Trends
Japan is changing its pricing formulas, but other major HTA bodies are also changing their policies in 2026.
| Country | 2026 Policy Outlook | HTA Role |
| Japan | 15% cap on HTA price cuts; dynamic re-evaluation. | Adjusts prices after the drug is listed. |
| UK (NICE) | Increased the threshold from £20k-£30k to £25k-£35k per QALY in April 2026. | Decides if the insurance covers the drug (Gatekeeper). |
| Germany | Focuses on “added therapeutic benefit” for price talks. | Price negotiation based on evidence. |
The UK’s NICE increased its threshold for the first time in over 20 years to support industry growth and patient access. This is different from Japan, which focuses on controlling costs with mathematical formulas.
Chapter 6. Real-World Evidence and Success Stories
Japan is using more Real-World Data (RWD), such as health insurance claims (receipt data), to confirm a drug’s value in real clinical practice.
- Success Case (Dapagliflozin): The government evaluated this SGLT2 inhibitor for Chronic Kidney Disease (CKD). The analysis combined clinical trial data with Japanese RWD. It proved that the drug significantly reduces long-term dialysis costs. The ICER was about 1.28 million yen per QALY. This is well below the 5 million yen threshold, proving the drug is highly cost-effective.
Conclusion
In 2026, Japan enters the “Second Stage” of its HTA system. Evaluating a drug’s value is now a dynamic process that lasts throughout its time on the market. The 15% reduction cap and the new re-evaluation rules mean that economic evidence must be strong not just at launch, but always. For everyone in the healthcare industry, showing long-term economic value with Japanese data is now the most important key to success.
For me, the true “art of learning” in this field is not just tracking the changing formulas, but understanding how these policies ultimately affect real-world well-being. Keeping a steady eye on this balance is a core part of my ongoing inquiry.
Disclaimer: The views and opinions expressed in this article are solely those of the author and do not necessarily reflect the official policy or position of any affiliated organizations.
