Q（Question）

When a physician or pharmacist requests comparative information on the efficacy of one's own product versus a competing product, is it permissible to provide such information?

A（MHLW answer）

The handling of information provision is the same as A1.

Because simply comparing results from clinical trials with different patient backgrounds without adjustment may not constitute a scientifically fair comparison, it is necessary to disclose the sources of comparative information and to clearly indicate the positioning of primary and secondary endpoints, in accordance with the Guidelines.

So what (meaning): Efficacy comparisons must follow A1's four conditions and additionally require source disclosure and clear labeling of primary vs. secondary endpoints; unadjusted cross-trial comparisons are considered scientifically unfair.

So why (rationale): Efficacy data interpretation depends heavily on trial design and patient population, so disclosing limitations and endpoint positioning is required to prevent misunderstanding.

Commentary — background, application, practical notes

Comparative efficacy information has the most direct influence on prescribing decisions, so the scientific fairness requirement is applied with particular rigour. The central point Q3 makes explicit is that 'presenting results from clinical trials with different patient backgrounds side by side without statistical adjustment does not constitute a scientifically fair comparison.' This directly addresses the limitations of naive indirect comparisons — placing unadjusted numerical results from separate trials next to each other without a network meta-analysis.

A typical scenario is a physician asking 'is the improvement rate on the primary endpoint for product A higher than for product B?' Even if the manufacturer's own trial shows a 60% improvement rate on the primary endpoint while a separately conducted trial for a competing product shows 50%, those figures cannot simply be placed side by side if the trials differ in disease severity, patient age, or concomitant medications. What can be provided is information that clearly states each trial's design and conditions and explains that head-to-head evidence is not available.

Particular attention must be paid to the explicit labelling of endpoint positioning. Comparing data that appeared as a secondary endpoint in one trial against the primary endpoint result of another trial is not scientifically fair. When preparing a comparison table, the distinction between primary and secondary endpoints must always be shown, along with the control group design and observation period. A comparison table that omits this context risks being judged by regulators as lacking scientific fairness.