If you have psoriasis or a family history of psoriasis and you are experiencing joint pain and swelling, you could have psoriatic arthritis, a serious disease that may lead to joint destruction and disability.

New research from the National Psoriasis Foundation reveals that nearly one in four people with psoriasis -- the most common autoimmune disease in the country, affecting as many as 7.5 million Americans -- may have undiagnosed psoriatic arthritis, a type of inflammatory arthritis that affects the joints and tendons. This is in addition to the up to 2 million people already diagnosed with the disease.

The Psoriasis Foundation study found that 22 percent of psoriasis-only participants had significant symptoms of psoriatic arthritis, such as joint pain, pain that moved from one joint to the other; joints that were hot to the touch; and swollen, sausagelike fingers and toes. For the full data snapshot, see: www.psoriasis.org/survey

Other key findings revealed that people with psoriatic arthritis are not being diagnosed in a timely manner. Forty-four percent of these respondents said they experienced symptoms for a year or longer before being diagnosed. Nearly one in three reported a delay of two years or longer to receive diagnosis.

"It's vital to diagnose and treat psoriatic arthritis early in order to prevent or slow joint damage. Yet, nearly 30 percent of psoriatic arthritis patients said it took more than two years for a diagnosis," said Dr. Mark Lebwohl, chair of the National Psoriasis Foundation Medical Board.

In response to these findings, the Psoriasis Foundation Medical Board issued a set of recommendations for both people with psoriasis and medical professionals who treat them to evaluate for symptoms of psoriatic arthritis.

For people with psoriasis and/or a family history of the disease, the medical board recommends watching for the following symptoms, and if they experience one or more, to call their physician:

Pain, swelling or stiffness in one or more joints;

Joints that are red or warm to the touch;

Frequent joint tenderness or stiffness;

Sausagelike swelling in one or more of the fingers or toes;

Pain in and around the feet and ankles;

Changes to the nails, such as pitting or separation from the nail bed;

Pain in the lower back, above the tailbone.

"Up to 30 percent of people with psoriasis develop psoriatic arthritis," said Dr. Elaine Husni, a rheumatologist and psoriatic arthritis expert with the Cleveland Clinic in Ohio. "These guidelines could help millions of Americans with psoriasis recognize the signs of psoriatic arthritis early, so they can seek medical attention for a diagnosis and begin treatment. If untreated, the joint damage can be disabling."

Additionally, the findings show that psoriatic arthritis significantly impacts quality of life: 63 percent say they are unable to be as active as they once were, nearly half (47 percent) say the disease impacts their ability to work, 34 percent report difficulty getting in and out of a car and 34 percent have stiffness for more than two hours after waking.