Abstract
Psoriasis is a multisystem disease. The cutaneous and musculoskeletal manifestations (psoriatic arthritis) are well recognized. However, the other manifestations of psoriatic disease including metabolic syndrome, atherosclerotic cardiovascular disease, depression, poor self-esteem, and self-destructive habits including obesity, smoking and excess alcohol consumption are underappreciated. At the 2012 annual meeting of the Group for Research and Assessment of Psoriasis and Psoriatic Arthritis (GRAPPA), members addressed the need to develop uniform, validated, standardized outcome measures for psoriatic disease, measures that are useful to all stakeholders including patients, physicians, regulators, and payers.
Over the years, several differing models of psoriasis care have emerged: (1) Primary care physicians manage all aspects of psoriatic disease; (2) single specialists manage all aspects of psoriatic disease; (3) multiple specialists work independently on different aspects of psoriatic disease [patient sees a dermatologist for psoriasis and a rheumatologist for psoriatic arthritis (PsA)];(4) multidisciplinary clinics where specialists from different fields work together to care for the patient; and (5) patients drop out of the system, receive no psoriasis care from established medical facilities, or seek over-the-counter and/or alternative care.
While the optimal model would be multiple specialists contributing to care of patients with psoriasis, the reality is that many patients receive no care, or care only from primary care physicians.
We need better psoriasis outcome measures that are useful in the clinic setting and that satisfy the needs of physicians, regulators, payers, and patients, because access is the major obstacle to optimal psoriasis care (Tables 1, 2, 3). In the United States, patients have limited ability to see doctors offering the full repertoire of treatments. Only 25% of US dermatologists use methotrexate, which has been approved for use in psoriasis for decades1. In a National Psoriasis Foundation (NPF) survey, about 50% of patients with severe psoriasis are treated only with topical therapies2.
Physician-reported disease severity measures in psoriasis.
Patient-reported disease severity measures in psoriasis.
Patient-reported quality-of-life measures in psoriasis.
Many dermatologists do not inquire about signs and symptoms of PsA, nor the other manifestations of psoriatic disease, primarily because of economic disincentives3,4. Treating moderate to severe psoriasis patients who require systemic treatment increases office overhead and decreases revenue, especially when compared to treating patients in need of surgical or cosmetic interventions. Payers often stratify physicians based on their cost efficiency (physician tiering), which could appear less cost effective if they offer a full spectrum of therapies for patients with psoriasis. Primary care physicians (PCP) may not refer their patients to specialists who offer a full range of treatments because PCP are financially rewarded for not referring to specialists (e.g., capitation, accountable care organizations). Additionally, patients may be levied high copays or coinsurances to obtain expensive drugs or see physicians offering expensive treatments. Many primary care physicians receive limited training during residency and therefore have inadequate knowledge about the serious aspects of dermatologic diseases. Many patients are not aware of the natural history of their psoriatic diseases or the range of treatment options, and they may not have appropriate expectations regarding the benefits and risks of these treatments. Importantly, patients may not be aware that physicians differ widely in their expertise with regard to psoriasis care. If patients lack access to a comprehensive psoriasis care center or specialists experienced in treating psoriasis, their likelihood of achieving significant improvement in psoriasis severity and their quality of life (QOL) is lower than those with such access. Most patients with moderate to severe psoriasis do not know that they bear an increased risk of dying prematurely due to their psoriasis.
Current psoriasis outcome measures lack aspects of truth, discrimination, and feasibility. They do not measure key aspects of psoriatic disease and are not useful in clinical practice. Further, psoriasis-specific outcomes are not currently captured in routine clinical databases. When payers make decisions on psoriasis treatment algorithms and which physicians to favor for their quality and cost effectiveness, the decision makers do not have available data outside of clinical trials. Psoriasis outcome measures may partially address the needs of clinical researchers and regulators but often do not address the needs of patients or payers, and may not be practical to use in the clinic setting (Tables 1, 2, 3). Many aspects of psoriatic disease are not addressed at all, e.g., QOL, PsA, nail disease, metabolic syndrome, cardiovascular morbidity and mortality, and cost efficacy. Too often, psoriasis is viewed by payers and regulators as largely a cosmetic problem, i.e., not as serious as the rheumatologic disorders.
Table 1 shows the physician-based disease severity outcome measures used currently for regulatory approval and their limitations. The Psoriasis Area and Severity Index (PASI) has been validated in multiple phase 2 and 3 clinical trials5,6,7,8. It has acceptable intraobserver variability but falls short with respect to interobserver variability. It lacks sensitivity, especially in patients with milder disease. It is impractical to use in the clinic setting. It does not measure patient symptoms, e.g., itch, and measures only severity of skin disease. It measures none of the other aspects of psoriatic disease listed above.
The Physician Global Assessment (PGA)5,7,9, although relatively easy to use, with acceptable intra- and interobserver variability, and practical for use in the clinic, fails on multiple levels. It is not standardized (it has both 5-point and 6-point scales), which make the results difficult to compare. PGA measures only lesion morphology and not body surface area (BSA) (Table 1). Investigators are often confused or inconsistent about assessing current lesions or describing them. Partially cleared lesions are difficult to assess. PGA assumes all lesions clear identically at the same rate; in reality this often does not happen. Like PASI, it does not address patient symptoms, QOL, nail disease, or the multisystem expression of psoriatic disease.
While BSA is practical to use in the clinic setting10, it too fails in multiple ways. There is a large degree of interobserver variability. It does not measure the quality or morphology (scaling, erythema, thickness) of lesions. Like PASI and PGA, it does not measure nail changes, QOL, patient symptoms, or other aspects of psoriatic disease. Recently the product of BSA plus PGA has been suggested as a better alternative to the use of BSA and PGA separately7. PASI, BSA, and PGA have been the 3 most common efficacy measures used in phase 2 and 3 clinical trials.
Dermatology Life Quality Index (DLQI) is the most common QOL instrument used in phase 2 and 3 clinical trials of psoriasis (Table 3)11,12. However, DLQI is a generic dermatology QOL measure that is not specific to psoriasis and does not adequately identify the unique QOL of psoriatic disease.
Nail disease has been measured most often in clinical trials by the Nail Psoriasis Severity Index (NAPSI)13. Advantages include being simple to calculate, sensitive to change, and reproducible in clinical trials. However, practicing dermatologists will not be likely to include it in their health records.
Other, less commonly used skin symptom measurement tools include Overall Lesion Assessment14, Overall Lesion Severity Scale15,16, Psoriasis Severity Index17, Psoriasis Assessment Severity Score18,19, Simplified PASI20, Psoriasis Log-based Area and Severity Index19,21, Psoriasis Exact Area and Severity Index19,21, Copenhagen Psoriasis Severity Index22, National Psoriasis Score14,23, Lattice System Physician’s Global Assessment7, Salford Psoriasis Index24, and Dermatology Index of Disease Severity25,26,27 (Table 1). Other patient-assessed disease severity measures are summarized in Table 216,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45. Use of QOL measures is described in Table 311,33,34,35,43,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63.
Dermatologists need to develop uniform, validated, standardized outcome measures for psoriatic disease that are useful to all stakeholders including patients, physicians, regulators, and payers. These measures need to be applicable not only to clinical researchers but also to practicing dermatologists. They have been discussed at an international meeting in January 2013 where attendees determined whether an OMERACT (Outcome Measures in Rheumatoid Arthritis)-like approach will improve the culture of assessment in dermatology. Participants included representatives from OMERACT, GRAPPA, the NPF, patient leaders, payers, regulators, clinical researchers, and epidemiologists/statisticians. Pharmaceutical industry sponsors were invited to attend as observers. A review was conducted of how OMERACT identified which domains to measure for fibromyalgia and PsA and how they designed and validated specific outcome measurement tools for those diseases. Representatives from all attending groups discussed the benefits and shortfalls of current psoriasis outcome measurement instruments and provided their perspectives on what these tools should measure.
The group used techniques similar to those used by OMERACT to identify which disease domains to study64. The group discussed whether to focus solely on the cutaneous manifestations, or if outcome tools should include other aspects of psoriatic disease (e.g., patient-related symptoms, QOL, nail disease, PsA, metabolic syndrome, cardiovascular morbidity and mortality, cost efficacy, and comparative efficacy). Additionally, the group discussed creation and maintenance of an outcomes website for posting key articles and providing a forum for online debate. A Delphi process is being conducted over the following 6 months in order to pick domains to assess with outcome measurement tools. A second psoriasis outcomes meeting is planned to coincide with the GRAPPA annual meeting in Toronto, Canada, in July 2013. Proceedings of all meetings will be submitted for publication.
In conclusion, in order to improve the access of patients to optimal care we need new psoriasis outcome measures that meet the needs of all stakeholders and are feasible to use in clinical practice. It is hoped that improved outcome measures will lead to improved access for patients. The finish line is not at regulatory approval or when an article is published in the New England Journal of Medicine or The Lancet. It is when patients lead their daily lives free from psoriasis, psoriatic arthritis, and their associated comorbidities.
Footnotes
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Supported in part by a grant from the Advancing Innovation in Dermatology Foundation.
