Who Gets Psoriatic Arthritis & Why?

Psoriatic arthritis affects approximately one-tenth of 1% of North Americans:

  • It is most common in Caucasians, with an incidence rate of 2%; it is uncommon in Asians and African blacks
  • Equal numbers of men and women suffer from the disease, except:
  • In cases where only the fingers are affected, primarily experienced by males
  • In cases where joints on both sides of the body are affected, similar to rheumatoid arthritis, primarily experienced by females
  • In cases of spinal involvement, where male cases outnumber female cases 3:1
  • Typical age of initial onset of PSA is age 30-55, whereas peak age of onset for psoriasis itself is age 5-15.  There can be late stage onset as well.

The cause of psoriatic arthritis (and psoriasis in general) is unknown. However, studies strongly suggest genetic predisposition towards PSA. First-degree relatives of PSA sufferers are believed to have a 50% likelihood of developing some form of arthritis in their lifetime.

There are also possibilities of environmental and immunologic factors, thought none have yet been proven.   It is thought that trauma to part of the body can sometimes trigger psoriasis and psoriatic arthritis.