Psoriasis affects each patient differently; the scaly patches can grow in various areas and it is unique to the individual. The severity of psoriasis can also vary from patient to patient. For some patients, it is a tiny patch on the arm, but for others it is itchiness on the scalp that can affect their entire day, or it may even cover their entire body.
Understanding the severity of psoriasis is an important step in every psoriasis patient’s journey, it can help them identify the progression of their condition as well as help their doctors provide them with the optimum treatment. However, there are still patients out there who are unaware of the importance of understanding the severity and are not sure how to determine the severity.
One of the simplest ways to determine the severity of psoriasis is by understanding how much of the total body surface area (BSA) is covered with psoriasis patches. Patients can use their hand for the estimation. One hand is generally equivalent to 1% of the BSA1.
The severity of psoriasis based on BSA:
- Mild psoriasis is when less than 3% of the BSA is affected.
- Presence ofisolated patches
- Little impact on the quality of life
- Moderate psoriasis is when 3% to 10% of the BSA is affected
- May affect the arms, legs, torso, and scalp
- Significant impact on their quality of life
- Severe psoriasis is when more than 10% of the BSA is affected
- Affects large areas on the face, palms or soles of the feet have patches
- Severe impact on their quality of life
Another way to measure the severity of Psoriasis is through PASI, acronym for Psoriasis Area Severity Index. The severity and body surface area are used together to calculate the PASI score.
The PASI looks at several factors to determine the score:
- redness of skin
- thickness of lesions
- the extent of scaling
- and the percentage of the body’s surface that is affected
In PASI, each area of the body (head and neck, arms and hands, trunk and lower body) is assessed and then assigned a severity score. The overall scores will be calculated to get the final PASI score2.
A score below ten means that the psoriasis may be ‘mild’. But this also depends on the location of the psoriasis patches. The first line treatments such as emollients and topical lotions might be all that is required to manage the condition.
PASI scores above ten may be considered ‘moderate to severe’. In this case, lotions may not be sufficient and more powerful forms of treatment might be required for the patient3.
Knowing whether the psoriasis is mild, moderate, or severe can aid doctors in figuring out the most appropriate treatment for patients. With PASI/BSAscore, doctors can gauge whether the psoriasis is getting better or worse and if the treatment is working. These scores are useful for disease monitoring.
Patients can speak to their doctors if they are unsure of their psoriasis severity and start tracking their psoriasis progression.
This article was inspired by Ask Alia.
- How Severe Is Your Psoriasis?. WebMD. Accessed 11 August 2020 https://www.webmd.com/skin-problems-and-treatments/psoriasis/how-severe-your-psoriasis
- The Psoriasis and Psoriatic Arthritis Alliance. Psoriasis Area & Severity Index. Accessed 17 July 2019 http://www.papaa.org/articles/psoriasis-area-severity-index
- Responsiveness to change and interpretability of the simplified psoriasis index. Chularojanamontri L, Griffiths CE, Chalmers RJ. J Invest Dermatol. 2014 Feb;134(2):351-8. http://www.ncbi.nlm.nih.gov/pubmed/?term=23897275 http://www.nature.com/jid/journal/v134/n2/full/jid2013318a.html