What to Aim at in “Treat to Target” for Psoriatic Arthritis

January 16, 2019

How much confidence do you have in your treatment target?

Coates and fellow researchers1 in the UK have determined that when it comes to treat-to-target, very low disease activity (VLDA) is the optimal target in psoriatic arthritis (PsA).

Treat-to-target PsA
An international task force recommended in 2013 that the target for treatment in PsA should be clinical remission/inactive disease of musculoskeletal involvement, including arthritis, dactylitis, enthesitis, and axial disease. Since 2013, the Tight Control of PsA (TICOPA) criteria have improved clinical and patient-reported outcomes in PsA, using minimal disease activity as a target, while drug-related adverse events have increased.

The authors sought to determine which patients fulfill the criteria of VLDA and remission as well as how much residual disease is present.

The study
The investigators examined data from the TICOPA randomized controlled trial and an Italian real-life data set of patients with PsA. Four definitions of remission/inactive disease were used: VLDA, Disease Activity Index for PsA (DAPSA) remission, clinical DAPSA remission, and near remission in the PsA Disease Activity Score (PASDAS). Proportions of subjects achieving each criterion were calculated.

Only patients with full data sets were in the final analysis. A total of 170 patients were included.

Next: the results and take-home points for clinicians

The results
All measures were able to differentiate the TICOPA trial treatment groups (P < .03). Fewer patients met the VLDA criteria when compared with DAPSA or clinical DAPSA remission requirements.

Residual active disease was low for all measures. Higher levels of residual active disease were seen in DAPSA and clinical DAPSA compared with VLDA, particularly for psoriasis. In all measures, the proportion of patients with elevated C-reactive protein was similar and low.

Take-home points
• Clinicians who are looking for a more rigorous measure of low disease activity in PsA should look to the VLDA criteria.

• It appears that DAPSA and PASDAS scores may hide some residual disease activity in PsA, which leaves clinicians with an unwarranted confidence in their treatment target.

• With treat-to-target as the law of the land, clinicians should consider the VLDA criteria as the most valid definition of remission in PsA.

• Even when the VLDA criteria are used, patients with PsA should be counseled to report any symptoms they feel are not being adequately addressed.

Final thoughts
It should be clear when reading the plethora of meta-analyses and review articles on remission criteria and outcomes in rheumatology that we are shooting at a moving target. In this study, the authors validate VLDA as an important diagnostic tool in PsA. Ultimately, these criteria enable us to identify more patients who are still suffering after meeting other, less rigorous criteria.

As always, these tools should be interpreted with individualized clinical judgment and patient input.

References:

1. Coates LC, Lubrano E, Perrotta FM, et al. What should be the primary target of “treat to target” in psoriatic arthritis?J Rheumatol. 2019;46:38-42. doi: 10.3899/jrheum.180267. Epub 2018 Sep 15.