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Is Using PASI 100 Realistic in a Real-Life Setting?


More real-world evidence is needed to determine what role a score of 100 on the Psoriasis Area and Severity Index (PASI) might have in daily clinical practice, according to a recent review.

A score of 100 on the Psoriasis Area and Severity Index (PASI)—representing complete resolution of a patient’s lesions—is achievable in the controlled environment of clinical trial settings, but more real-world evidence is needed to determine what role it might have in daily practice, according to a literature review.

Even in randomized clinical trials (RCTs) of drug therapies, PASI 100 response rates vary widely, according to a recent article published in The Journal of Dermatological Treatment. There are also numerous instances, particularly with classical systemic therapies like methotrexate, where data on PASI 100 scores are scarce. Still, given that achieving completely clear skin is clinically meaningful in terms of disease severity and patient-reported health reported quality of life, the score has found utility in the research context. It is considered the gold standard for both research and daily practice and is recommended for clinical trials by regulatory agencies.

The impact of psoriasis, which affects approximately 100 million people worldwide, on quality of life is comparable to that of heart disease or diabetes. Approximately 20% of patients have moderate to severe disease.

Response treatments can be assessed using the PASI 50, 75, 90, or 100 responses. PASI 75 refers to 75% improvement, which denotes substantial improvement in affected skin. But even with improvement, patients’ quality of life may still be significantly impacted.

The authors analyzed 65 studies; inclusion criteria were other phase 3 or phase 4 RCTs, other systematic literature reviews, and other observational prospective studies with more than 300 patients. Patient response to treatment for psoriasis or plaque psoriasis)was analyzed based on the PASI 100 score, compared with any treatment or placebo.

The researchers also reviewed several national and international consensus and clinical practice guidelines to look for recommendations or comments regarding the use of of PASI 100.

The study found great variability in PASI 100 response rates in RCTs of systemic therapies—nearly all of which were biologics—depending on the drug and the point in time of treatment.

The highest PASI 100 response rates were obtained with interleukin-17 (IL-17), IL-12, and IL-23 inhibitors. These studies illustrated the drugs’ superiority over tumor necrosis factor (TNF) inhibitors adalimumab and entanercept. However, there was no data regarding infliximab , likely because any studies precluded usage of the PASI 100 tool.

Patients on methotrexate achieved PASI 100 at 16 weeks at 7.3% of the time. TNF inhibitor rates reached as high as 21.8%-34.8% at 1 year. IL-17 inhibitors reached 41.4%-67.5% at 1 year. IL-12/23 inhibitors were 41.8%-56.3% at 1 year.

The authors said the issue with using PASI 100 in daily practice, however, is that clinical practice guidelines barely comment on it as a treatment goal. Criticisms of PASI are that the measure is too complex and resource intensive for use. There are also difficulties with low response distribution as well as in assessing patients who are affected on less than 10% of their body surfaces.

The authors found PASI 100 to be a useful measure of the efficacy of biologic therapies, keeping in mind that the findings are obtained in the ideal conditions of RCTs.

“As a consequence, more research, especially more real world evidence is needed in order to determine the role and applicability of PASI 100 in daily practice,” the authors wrote.

PASI 90 to 100 scores should be considered an ideal target in real-life conditions, the authors said, because they represent real improvement in quality of life.


Belinchón I, Dauden E, Ferrándiz C, et al. PASI 100 response rates in moderate to severe psoriasis: A systematic literature review and analysis of clinical practice guidelines. J Dermatolog Treat. Published online February 21, 2021. doi:10.1080/09546634.2021.1890683

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