What is the role of absolute effect estimates in Joint Clinical Assessment (JCA)?

 

BACKGROUND:

🚩Before we can discuss this question, we need some methodological background:

When presenting results of clinical data, you can use two different types of effect estimates – absolute and relative effect estimates – to quantify the treatment effect between study arms.

 

RELATIVE & ABSOLUTE EFFECT ESTIMATIONS:

📈 Relative effect estimates describe the effect proportional to the baseline risk measured in the comparator arm. They travel well across populations but hide the actual magnitude of benefit. Typical examples are risk ratios or odds ratios for binary data and hazard ratios for time-to-event data.

🧮 Absolute effect estimates describe the actual change experienced by patients. They depend heavily on baseline risk but tell you what matters clinically: how many people are truly helped. Typical examples are risk differences or number needed to treat (NNT) for binary data and median survival differences or restricted mean survival time (RMST) for time-to-event data.

 

WHY BOTH MATTER – A QUICK HYPOTHETICAL EXAMPLE💡:

Two trials report the identical hazard ratio of 0.70 for overall survival:

🔹 Trial A: Median OS: 32 months (control) vs. 48 months (treatment) ➡️ Median difference: +16 months

🔹 Trial B: Median OS: 4 months (control) vs. 6 months (treatment) ➡️ Median difference: +2 months

 Same relative effect (HR = 0.70), but the absolute survival gain is eight times larger in Trial A. The hazard ratio alone would suggest equal benefit, while the absolute measure (median survival difference) reveals how much extra time patients actually gain ✅.

 

⚖️ With the guidance on filling in the JCA dossier template and the included table template collection, the rules for JCA appear to be very clear: both relative and absolute effect estimates matter, and both should be presented.

 

PRACTICAL IMPLEMENTATATION:

However, the recently published JCA reports show a different picture:

🔹 Only relative effect estimates were requested in the assessment scope and discussed by the assessors.

🔹 In addition, the assessors did not comment when the HTD did not provide absolute effect estimates.

 

OUR OPINION:

Our opinion after returning to our initial question: At this stage, we cannot give a clear answer due to the discrepancy between the theoretical guidance and its practical implementation. 🏁

 

👀 It will be very interesting to observe how this topic is handled in the upcoming JCA reports, and whether further clarification will be provided by the Coordination Group.