Predictors for clinical outcome in psoriatic arthritis – what have we learned from cohort studies?

Abstract

Psoriatic Arthritis (PsA) is a heterogeneous disease that ranges from a mild form of oligoarthritis to destructive polyarthritis. The burden of disease can be severe and comparable to that of rheumatoid arthritis. Identifying predictors of worse outcome may improve the understanding of the underlying mechanisms of the disease and may guide therapeutic management at the individual level. Longitudinal cohort studies identified predictors of long-term outcomes such as joint damage, physical function and work disability in PsA. In general, male gender and lower burden of inflammation at presentation predict better outcome while a delay in diagnosis, disability and joint damage are associated with worse long term outcomes. Several HLA alleles also identify patients who are likely to sustain joint damage.

Keywords::

• cohort
• epidemiology
• predictors
• psoriatic arthritis
• risk

Financial & competing interests disclosure

The authors’ clinic is supported by a grant from the Krembil Foundation. L. Eder has been supported by a post-doctoral fellowship from Janssen Canada and Amgen Canada. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• The functional, social and economic burden of PsA can be significant and comparable to that of rheumatoid arthritis.

• Identifying predictors of worse outcome may identify the underlying mechanisms of the disease and direct the therapeutic management at the individual level.

• Remission and minimal disease activity state are achievable goals and are associated with lower disease activity at baseline, early diagnosis, improved physical function and male gender.

• Overweight and obesity reduce the likelihood of achieving minimal disease activity, while weight reduction can improve the probability of achieving this goal.

• Joint damage is a good surrogate of poor physical function and is predicted by elevated tender and swollen joint counts, increased inflammatory markers and the presence of dactylitis.

• Predictors of better outcome of treatment with TNF-α blockers include male gender, younger age, high level of inflammation at baseline and concomitant use of methotrexate.

• Several HLA antigens can identify patients at risk of developing joint damage. These markers include HLA-B27, B39 and DQw3, while B22, C6 and DR7 are associated with lower probability of developing joint damage.

• Older age, female gender, longer disease duration, increased joint damage, smoking and delayed diagnosis at presentation predict subsequent disability in patients with PsA.