- Design
- Multicentre registry cohort with trajectory modelling and landmark analysis
- Population
- 843 patients with rheumatoid arthritis treated with JAK inhibitors
- Primary outcome
- CDAI trajectory over 52 weeks
- Effect
- Optimal thresholds CDAI 12.0 at week 4 and 9.3 at week 12; 65% rapid responders, 4% persistent non-responders
This multicentre registry followed 843 patients with rheumatoid arthritis starting a JAK inhibitor and modelled their Clinical Disease Activity Index over 52 weeks.
Four patterns emerged: rapid responders (64.9%), partial responders with persistent residual activity (18.1%), responders starting from high activity (12.7%), and persistent non-responders (4.3%). Week-52 remission ranged from 0% to 47.7% across these groups. Adding the absolute CDAI at week 4 or week 12 sharply improved prediction of a favourable course; the change from baseline added almost nothing. The best thresholds were a CDAI of 12.0 at week 4 and 9.3 at week 12. Internal validation showed good calibration.
This fits treat-to-target practice: an early, absolute measurement tells you more than whether a patient is improving. A patient still above about 9 at 12 weeks is unlikely to reach a good trajectory and merits a review of treatment rather than more waiting.
- Measure CDAI at baseline, week 4 and week 12 after starting a JAK inhibitor.
- Treat a week-12 CDAI above about 9 as a signal to review adherence, dose and the choice of drug.
- Judge response on the absolute score, not only on how much it has fallen.
- Combine with patient preference and safety considerations before switching.
Why it matters
It gives a concrete, early checkpoint for a decision that is easy to keep deferring.
Don't overread it
This is observational registry data, internally validated only; thresholds may differ in other populations and for biologics.
The statistics, in plain English
A threshold of 9.3 was the value that best separated patients who went on to a favourable trajectory from those who did not. Like any cut-off, some patients above it will still do well and some below will not.
Read the rest in the app
You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.
Scan to keep reading on your phone. No account needed to start.
Tomorrow morning, before your first patient
One edition a day for rheumatology, written by the desk, every claim tied to its paper. Six minutes.
Get the app — free