NEW YORK – For the skin component of psoriatic arthritis, consensus about how high to set the bar for disease control continues to elude experts, judging from a debate about the value of "clear" or "almost clear" as the most acceptable treatment endpoints.
Current therapies in psoriatic arthritis (PsA) are sufficiently effective to support a treat-to-target approach for both skin lesions and joint inflammation, but there is lack of consensus about which metrics should be employed to define any specific target for skin lesions, according to Dr. Joel Gelfand, medical director of the clinical studies unit in the department of dermatology at the University of Pennsylvania, Philadelphia. He noted that even if the goal is the absence of skin involvement, no one agrees on what method should be used to document this endpoint.
Dr. Joel M. Gelfand
"No one in clinical practice uses PASI," maintained Dr. Gelfand, referring to the Psoriasis and Area and Severity Index, which is one of the most widely accepted standards for judging efficacy in treatment trials. Speaking at the joint meetings of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA) and the Spondyloarthritis Research & Treatment Network, Dr. Gelfand said most objective scoring systems, such as PASI, are too labor intensive. Clinicians tend to use their own system for documenting relative control of skin lesions in the medical record.
Evaluating disease control without applying a reproducible, broadly used metric has numerous potential problems, according to Dr. Gelfand. Most importantly, it prevents objective evaluation of whether treatment targets are being met. This obscures efforts to document benefit relative to either clinical goals or optimal care. Dr. Gelfand made the analogy to the treatment goals created for blood pressure, blood glucose, or cholesterol, where the targets are clear and a change in treatment is warranted if the target is not reached.
This point of view resonated with the audience of dermatologists, rheumatologists, and PsA patients attending the meeting. In an electronic audience poll, there was nearly 100% agreement that a treat-to-target approach is appropriate for skin lesions but no strong consensus on what the target should be. In the poll attempting to define consensus, 32% agreed with a target of less than 3% body surface area (BSA) while 48% agreed the BSA target should be less than 1%. It is notable that dermatologists were more likely to accept a less rigorous BSA than rheumatologists. The majority of patients agreed the target should be less than 1% BSA, although this group represented less than 10% of the audience.
Not surprisingly, health-related quality of life studies show measurable differences between "clear" and "almost clear" skin lesions in PsA patients whether measured by PASI, BSA, or other measures, according to Dr. Gelfand, but he cautioned that it is important to be realistic about goals. He suggested that a target that exposes patients to unacceptable side effects is the wrong target, and this may be the source of dissension among experts.
Asked for a comment, Dr. Wolf-Henning Boehncke, professor and chair of the department of dermatology at the University of Geneva agreed in principle with the treat-to-target approach. However, Dr. Boehncke, who is the current president of GRAPPA, also emphasized simple and practical assessment tools and achievable endpoints.
"We must define targets that are reasonable," Dr. Boehncke said. While complex patient assessment tools are not likely to be widely used by clinicians, unrealistic targets can be counterproductive if they are not considered in the overall context of tolerability and patient satisfaction.
Dr. Gelfand has or has had financial relationships with AbbVie, Amgen, Celgene, Eli Lilly, Genentech, Janssen, Merck, Novartis, and Pfizer.