Psoriatic Arthritis: The Basics
Psoriatic arthritis is a form of inflammatory arthritis that can affect some of the millions of Americans who have psoriasis. Psoriasis is a skin disease that causes a red, scaly rash, most commonly over the elbows, knees, ankles, feet, hands, and other areas.
Are there different types of psoriatic arthritis?
There are five types of psoriatic arthritis. It is important to know which type of psoriatic arthritis you have and to understand the characteristics so that it may be treated properly.
Symmetric psoriatic arthritis: Symmetric arthritis affects the same joints -- usually in multiple matching pairs -- on opposite sides of the body. Symmetric psoriatic arthritis can be disabling, causing varying degrees of progressive, destructive disease and loss of function in 50% of people with this type of arthritis. Symmetric psoriatic arthritis resembles rheumatoid arthritis.
Asymmetric psoriatic arthritis: Asymmetric arthritis typically involves one to three joints in the body -- large or small -- such as the knee, hip, or one or several fingers. Asymmetric psoriatic arthritis does not affect matching pairs of joints on opposite sides of the body.
Distal interphalangeal predominant (DIP): Distal interphalangeal predominant psoriatic arthritis involves primarily the small joints in the fingers and toes closest to the nail. DIP psoriatic arthritis is sometimes confused with osteoarthritis, a chronic disease that causes the deterioration of joint cartilage and bone as well as bone spurs at the joints.
: Spondylitis affects the spinal column and may cause inflammation and stiffness in the neck, lower back, spinal vertebrae, or sacroiliac region (pelvic area), making motion difficult. Spondylitis also can attack connective tissue, such as ligaments, or cause arthritic disease in the joints of the arms, hips, legs, or feet.
Arthritis mutilans: Arthritis mutilans is a severe, deforming, and destructive form of psoriatic arthritis that primarily affects the small joints in the fingers and toes closest to the nail. This leads to lost function of the involved joints. It also is frequently associated with lower back and neck pain. Fortunately, this type of psoriatic arthritis is rare.
Who is at risk for psoriatic arthritis?
Affecting men and women equally, about 10% to 30% of people with psoriasis develop psoriatic arthritis. Psoriatic arthritis may develop at any age, but usually affects people between the ages of 30 and 50. While the cause is not known, genetic factors, along with the immune system, likely play a role in determining who will develop the disorder.
As many as 40% of people with psoriatic arthritis have a family history of skin or joint disease. Having a parent with psoriasis triples the chance of getting psoriasis yourself and thus increases the chance of developing psoriatic arthritis.
What triggers psoriatic arthritis?
Certain factors may trigger psoriasis, including the following:
Injury to the skin: Injury to the skin has been associated with plaque psoriasis. For example, a skin infection, skin inflammation, or even excessive scratching can trigger psoriasis.
Sunlight: Most people generally consider sunlight to be beneficial for their psoriasis. However, a small minority find that strong sunlight aggravates their symptoms. A bad sunburn may worsen psoriasis.
Streptococcal infections: Some evidence suggests that streptococcal infections may cause a type of plaque psoriasis. These bacterial infections have been shown to cause guttate psoriasis, a type of psoriasis that looks like small red drops on the skin.
: Psoriasis typically worsens after an individual has been infected with HIV. However, psoriasis often becomes less active in advanced HIV infection.
: A number of medications may aggravate psoriasis. Some examples are as follows:
- Lithium: Drug used to treat bipolar disorder
- Beta-blockers: Drugs used to treat high blood pressure
- Antimalarials: Drugs used to treat malaria
Emotional stress: Many people see an increase in their psoriasis when emotional stress is increased.
: Cigarette smokers have an increased risk of chronic plaque psoriasis.
Alcohol: Alcohol is considered a risk factor for psoriasis, particularly in young to middle-aged men.
Hormone changes: The severity of psoriasis may fluctuate with hormonal changes. The disease frequency peaks during puberty and menopause. A pregnant woman's symptoms are more likely to improve than worsen during pregnancy, if any changes occur at all. In contrast, symptoms are more likely to flare in the period after childbirth, if any changes occur at all.