Finding the right psoriasis treatment for you depends on how bad your symptoms are. To determine if psoriasis is mild, moderate, or severe, a dermatologist relies on several criteria, from what it looks and feels like to how it affects your life.

For people like Phyllis Spool, tracking psoriasis symptoms can be a real challenge. A retired preschool teacher in Worcester, Massachusetts, Spool remembers how psoriasis made her ankles bleed when she was in kindergarten. Now she feels like she wakes up to “a new patch in a different spot every morning.”

At each visit, Spool’s doctor will take pictures of her psoriasis patches. At the following visit, they compare pictures to determine how the condition has changed, and evaluate her treatment going forward.

Body Surface Area

One of the key factors in diagnosing and treating psoriasis is assessing how much of a patient’s body surface area (BSA) is affected by the condition. The area covered by the palm of your hand and fingers, for instance, equals 1 percent of your BSA.

Based on BSA alone, psoriasis severity level is characterized as:

  • Mild, if the affected BSA is less than 3 percent
  • Moderate, if it’s between 3 and 10 percent
  • Severe, if it’s greater than 10 percent

The Psoriasis Area and Severity Index (PASI) is a scoring system used to calculate severity based on the amount of body surface area affected as well as the combined redness, thickness, and scaling of the psoriasis lesions.

Another method of scoring used by dermatologists is the Investigator’s Global Assessment (IGA) or the Physician Global Assessment (PGA). This is a 5-point scale on which clear skin is scored as a 0 and severe patches are rated a 5.

“I go over the BSA and IGA every time I see a patient,” says Jerry Bagel, MD, director of the Psoriasis Treatment Center at Windsor Dermatology in East Windsor, New Jersey.

The location of the psoriasis is a factor, too. Your dermatologist may characterize the condition as more severe, regardless of your BSA, if you have:

  • Patches in visible or sensitive places, like your face, genitals, hands, or nails
  • Patches that make it hard for you to walk or use your hands

How Psoriasis Affects Your Life

Dr. Bagel sometimes asks patients to answer a questionnaire known as the Dermatology Life Quality Index (DLQI) to measure how much psoriasis affects their lives. The DLQI assesses a skin condition’s impact on a person’s work, relationships, ability to do things, and mood.

Spool discusses her condition’s emotional and physical toll with her doctor. She describes being embarrassed in her own house whenever skin flakes fall onto the floor, or being troubled at night if she can’t bend her arms “because the skin feels too tight.”

Bagel says that your doctor doesn’t know how much psoriasis impacts your life at any given time unless you share your thoughts and feelings. “You may have felt like it was routine to treat a patch on your face before,” he explains. “But if it’s time for your prom or wedding, you may feel a new urgency.”

How Sick Is Psoriasis Making You?

Having psoriasis puts you at risk for other medical conditions, too, from psoriatic arthritis to cardiovascular disease. In evaluating your condition and treatment plan, your doctor looks at complications or comorbidities you already have, as well as others that are considered a risk.

“I tell all my patients to see their primary doctor to get a physical each year,” Bagel says.

Jashin Wu, MD, director of dermatology research at Kaiser Permanente Los Angeles Medical Center in California, stresses the importance of factoring in emotional and mental health issues, such as depression, when evaluating the effects of psoriasis. Dr. Wu refers patients to the National Psoriasis Foundation to learn about support groups.

As Bagel puts it, “comorbidities change the algorithm of treatment plans.”

All of these factors, from the direct effects that psoriasis has on your skin to other emotional and physical complications, contribute to the management strategy that you and your doctor work out.