What Is Psoriasis Epidemiology?
Who gets psoriasis more often: women or men? And do your chances of developing this long-term skin condition go up based on your race, ethnicity, or age?
The field of epidemiology can help us answer these questions. It’s a branch of science that looks at how often diseases affect different groups of people and why. Medical experts can then use the information to plan and assess ways to prevent or manage diseases.
Psoriasis affects an estimated 7.5 million to 8 million people in the United States and about 125 million worldwide. Your immune system and your genes both play a role in causing it. Here’s a closer look at who tends to get this condition.
Is Psoriasis More Common in Women or Men?
The answer is neither. The condition seems to affect women and men equally.
Is Psoriasis More Common at Certain Ages?
You can get the condition at any age, but it’s more common in adults than in children. Many people with psoriasis start getting symptoms between the ages of 20 to 30 or between 50 to 60.
It’s not clear why the condition is more common in those two age groups, says Dawn Davis, MD, a professor of dermatology and pediatrics at the Mayo Clinic in Rochester, MN. There are several possible reasons -- with links to the immune system, aging of the skin, genes, health care access, and more -- but the exact reason is unknown, she says.
How Often Does Psoriasis Run in Families?
About 1 in 3 people with psoriasis say they have a relative who does too.
If one of your parents has the condition, you have roughly a 10% chance of getting it. If both of your parents have it, you have about a 50% chance of getting it.
While people who inherit certain genes are more likely to get psoriasis, some people who develop the condition don’t have any genes that raise their chances for it.
But even if you have genes that boost your odds of getting psoriasis, that doesn’t guarantee you’ll get it. Something needs to trigger it, causing it to show up for the first time. Some common psoriasis triggers include things like stress, skin injuries (like a cut or a bad sunburn), an infection (like strep throat), and cold, dry weather.
Things like these can lead your immune system to go haywire and make too much inflammation, bringing on psoriasis symptoms.
How Is Psoriasis Linked to Race and Ethnicity?
In the U.S., more white people tend to get diagnosed with the condition than people of color.
A 2021 study looked at the rate of psoriasis in certain racial and ethnic groups. The percentages of adults 20 years and older who’d been diagnosed with psoriasis in each group were:
- White: 3.6%
- Asian: 2.5%
- Hispanic: 1.9%
- Black: 1.5%
The rate of psoriasis hasn’t changed much in the U.S. since 2003, the researchers said.
Genes may be part of the reason that the condition is more common in white people. But psoriasis might be more common in people of color than research data suggests, experts say.
Some doctors misdiagnose psoriasis as eczema or a drug reaction in people of color, says Raman Madan, MD, a dermatologist in New York. Doctors often mistake it for infections like ringworm, too, Davis says.
Gaps in access to doctors and dermatologists are also an issue, she says. Past research has shown that it’s common for Black and Hispanic people to have worse access to health care than white people. That could also make people of color less likely to get diagnosed with psoriasis.
“We want to make sure that people of color have equal and equitable access to health care providers and specialists, including dermatologists,” Davis says.
Is Psoriasis More Common in Some Parts of the World?
The condition tends to become more common the farther away from the equator you live. It’s not clear why this is, but one study says it may be tied to differences in climate, genetic background, and environment.