- Design
- Single-centre randomised double-blind placebo-controlled trial
- Population
- 66 adults with moderately active psoriatic arthritis on stable treatment
- Primary outcome
- PASDAS low disease activity or remission at 12 weeks
- Effect
- 43% vs 65%; OR 0.4 (95% CI 0.13 to 1.18); p = 0.167
A single-centre, double-blind randomised trial in Rheumatology (5 October) gave a multispecies Lactobacillus and Bifidobacterium probiotic or placebo for 12 weeks to 66 adults with psoriatic arthritis of moderate activity on stable treatment. The primary outcome was reaching low disease activity or remission on the PASDAS score without a treatment change.
In the 56 analysed, 43% on the probiotic and 65% on placebo reached the target (OR 0.4, 95% CI 0.13 to 1.18; not significant). Gut permeability markers, immune cell profiles and stool microbiome did not differ between groups, and no serious product-related adverse events occurred.
Patients with psoriatic arthritis increasingly ask about probiotics, prompted by interest in the gut-joint axis. This is the first randomised trial, and it gives no support for adding one. It was small, so a modest benefit cannot be fully excluded, but nothing pointed in a favourable direction.
- Advise patients with psoriatic arthritis that a randomised trial found no benefit from a multispecies probiotic.
- Keep disease-modifying treatment decisions based on disease activity, not on supplements.
- Note that most improvement in both arms was in patient-reported pain and global assessment, consistent with a placebo response.
- Ask patients what supplements they take, as they may delay effective treatment changes.
Why it matters
It gives clinicians trial evidence to answer a question patients commonly ask.
Don't overread it
With 56 patients analysed, the trial could miss a small effect, and it tested only one probiotic product.
The statistics, in plain English
An odds ratio of 0.4 points the wrong way for the probiotic, but the interval (0.13 to 1.18) includes no effect, so the result is best read as no benefit shown rather than harm.
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