Reviews/Psoriasis Psoriatic Arthritis/Tofacitinib ACR20 in psoriatic arthritis
Psa JAK · PSA-JAK-03 · v2
The evidence looks at whether tofacitinib, a Janus kinase inhibitor pill, helps people with active psoriatic arthritis achieve a meaningful improvement in joint symptoms compared with a dummy pill. Three separate placebo-controlled trials, run in different patient groups, all found that more people on tofacitinib reached the ACR20 benchmark than those on placebo, and the difference was statistically reliable. One trial [1] gives clear numbers: half to just over sixty percent of treated patients responded, versus a third on placebo. The direction and the significance point the same way in every trial, which is why the panel judged the claim well supported. The main caveats are that two of the three trials come from the same manufacturer's programme and all three had industry funding, but these temper confidence only slightly.
Three placebo-controlled phase 3 randomised trials in the corpus report a statistically significant ACR20 improvement with tofacitinib versus placebo in active psoriatic arthritis, spanning distinct populations: csDMARD-inadequate responders [1], TNF-inhibitor-inadequate responders [2], and Chinese patients [8]. [1] provides the clearest figures, with ACR20 rates at month 3 of 50% (5 mg) and 61% (10 mg) versus 33% for placebo (P=0.01 and P<0.001). [2] reports significant improvement at both doses with superiority evident as early as Week 2. [8] states significantly greater ACR20 response versus placebo at month 3 but supplies no numeric rates. Direction and significance are consistent across all three included trials. The contested point: The evidence does not divide on direction or significance, which are uniform across [1], [2] and [8]. The only points of tension are structural: [1] and [2] share the same manufacturer programme, and [8] asserts significance without reporting numeric ACR20 rates, so its effect size cannot be independently checked against the corpus.
All 8 papers behind this claim with their DOIs and what each does to it, the panel’s arbitration, the evidence gap map and the open research questions. Free, and sent to your inbox.
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One reviewer's only job is to attack the finding. The challenges below were weighed before the grade was set.
OPAL Broaden [1] and OPAL Beyond [2] are arms of the same manufacturer development programme, so evidential independence between them is partial; only [8] is a fully separate registration study.
[8]'s abstract asserts significance but reports no numeric ACR20 rates, so effect size cannot be verified from the corpus — only direction and significance.
Where it remains uncertain. Two of the three trials [1], [2] belong to the same manufacturer programme and [8] reports no numeric ACR20 rates, so full evidential independence and effect-size verification are partial.
Aleatory
ACR20 rates in [1] range from 50% to 61% across the two tofacitinib doses versus 33% placebo, reflecting inherent variability in individual patient response.
Epistemic
[8] confirms significance but reports no ACR20 percentages, so the size of the effect in the Chinese population is not knowable from the corpus.
The load-bearing papers from a corpus of 8, each classified by what it does to the claim. Every DOI is taken from the corpus the claim was graded on.
Primary quantified ACR20 vs placebo with p-values in csDMARD-IR PsA.
“ACR20 response rates at month 3 were 50% in the 5-mg tofacitinib group and 61% in the 10-mg tofacitinib group, as compared with 33% in the placebo group (P=0.01 for 5-mg vs placebo; P<0.001 for 10-mg vs placebo)”
Panel auditInternal validity: high · scope of inference: csDMARD-inadequate-responder patients with active psoriatic arthritis at month 3.Key limitations: sample size not reported · csDMARD-IR population only · month 3 timepoint
Confirms significant ACR20 improvement vs placebo in TNFi-IR PsA.
“ACR20 response and change in HAQ-DI significantly improved with both tofacitinib doses vs PBO at M3 and were maintained to M6.”
Panel auditInternal validity: high · scope of inference: TNF-inhibitor-inadequate-responder patients with active psoriatic arthritis, months 3 to 6.Key limitations: no ACR20 numeric rates for the comparison · sample size not reported · TNFi-IR population only
Independent registration RCT replicating significant ACR20 vs placebo in a Chinese cohort.
“tofacitinib demonstrated significantly greater ACR20 response versus placebo at month 3”
Panel auditInternal validity: high · scope of inference: Chinese patients with active psoriatic arthritis at month 3.Key limitations: Chinese population only · no ACR20 numeric rates · sample size not reported
3 of 8 papers shown. The full review lists all of them, with the panel’s arbitration →
Claims are graded at each quarterly release, and re-graded between releases only when a pivotal trial lands. Every change is a new version of the claim.
Multiple independent RCTs directly and consistently report significant ACR20 vs placebo, matching the claim's exact wording.
Release 2026-q4 re-graded every claim from its corpus under protocol v0.19. An earlier release's grade is shown for the record; it came from an earlier protocol and is not a movement.
Assumptions that carry weight but are not themselves established.
The panel records the gap that would most move the claim, and the study that would close it.
Independent, non-industry replication. All three included trials [1], [2], [8] are industry-sponsored and two share one programme, so no fully independent confirmation of the ACR20 effect exists in the corpus. The panel rates this the highest-importance open gap for the claim, and names the study design that would close it: An investigator-initiated, publicly funded placebo-controlled trial of tofacitinib ACR20 in active PsA.
Open question: What is the numeric ACR20 response rate for tofacitinib versus placebo in the Chinese phase 3 population? Why it is still open: [8] states significance but reports no ACR20 percentages, so the effect size is not available in the corpus.
Priors is a sceptical first reader, not peer review, and not medical advice.
Release 2026-q4 · graded 18 Sep 2026 · protocol v0.19