Formulary Decisions and the Evolution of Psoriasis Treatment


William Malatestinic: Eli Lilly and Company, Indianapolis, IN

David Amato: Eli Lilly and Company, Indianapolis, IN

Steven R. Feldman: Wake Forest Baptist Medical, Winston-Salem, NC


William Malatestinic, PharmD, MBA, Eli Lilly USA, LLC, Indianapolis, IN 46225, Phone: 317-997-2005, Email:


Dr. Malatestinic is an employee and stockowner of Eli Lilly and Company. Dr. Amato is an employee and stockowner of Eli Lilly and Company. Dr. Feldman is a consultant for Novartis, Amgen, AbbVie, Celgene, Janssen, Galderma, and Eli Lilly and Company with research grants from Novartis, Amgen, AbbVie, Janssen, and Galderma. He is also a patent holder at Wake Forest University School of Medicine. 

Acknowledgements: Appreciation is expressed to Tamara Ball, MD, for writing and editorial contributions. Dr. Ball is employed by inVentiv Health Clinical, who contracted with Eli Lilly and Company for the technical writing of this manuscript.

Key Words

Abstract: Psoriasis is a common and significant illness characterized by systemic inflammation. In its mildest form, psoriasis can often be managed with relatively low-cost topical therapies; but for moderate-to-severe disease, which affects 20% of psoriasis patients, these solutions are neither very effective nor practical. Treatments that provide excellent outcomes for many patients with more severe disease are now available. The development of medications specifically targeting the inflammatory process associated with psoriasis has the potential to change the lives of patients with moderate-to-severe disease. However, access to medications can be challenging due to step-therapy protocols and limited formulary options. Specifically, formulary options for biologic use in psoriasis are often based on a product’s market share across multiple indications and resulting rebates. This article provides a comprehensive review of psoriasis and of the practical obstacles encountered in optimizing care of patients with moderate-to-severe disease. Implementing psoriasis-centered coverage policies may give psoriasis patients better access to safer, more clinically effective, and possibly more cost-effective treatment options.

Key Words: psoriasis, biologics, access, formulary, efficacy, safety.

Citation: Journal of Clinical Pathways. 2015;1(2):43–47. 

Received September 25, 2015; accepted November 16, 2015.


Psoriasis is an often-debilitating, chronic condition characterized by systemic inflammation that causes thick, red, and scaly skin lesions. Psoriasis affects up to 125 million people worldwide, and its prevalence varies by geography. In the United States, psoriasis affects upwards of 3% of the population. A recent population-based study found that the incidence of psoriasis in the United States is rising and has doubled within the last several decades. Psoriasis often arises in patients between the ages of 15 years and 35 years, although it can occur at any age and affects infants and older adults as well.1-3 Costs of psoriasis totaled $112 billion in 2013;4 approximately half of costs were due to direct costs (medication, photo therapy, provider visits, etc), whereas half were due to indirect costs (co-morbid illness, societal productivity, etc).

Genetics play an important and complex role in the etiology of psoriasis, with numerous genes identified as being associated with the presence of disease.5,6 As an inflammatory disease, multiple cell types and cytokines are involved in the pathogenesis of psoriasis. Recent research has identified that activation of a particular T-helper cell, the TH17 cell, is a key process in the development of psoriasis.7,8 Specific cytokines, notably interleukin 23 (IL-23) and IL-17A, are essential components of this inflammatory cascade.9

Psoriasis can be local in distribution, commonly affecting elbows, knees, or scalp, but it can appear in any location (Figure 1). A Psoriasis Area and Severity Index (PASI) score10 is a commonly used tool to measure the severity and extent of psoriasis in clinical trials. PASI combines an assessment of the severity of lesions (redness, thickness, scaling) and the percentage of affected area into a single score in the range of 0 (no disease) to 72 (maximal disease). Psoriasis causes itch and pain, with up to 90% of patients experiencing itch10 and up to 43% of patients experiencing pain.12 Mild disease (less than 3% of body surface area [BSA] affected) occurs in approximately 80% of patients, while moderate (3–10% BSA) to severe (>10% BSA) disease is present in 20% of patients.1 Psoriasis impacts quality of life, physical, psychological, and social functioning, regardless of the extent of involvement.13-16

plaque psoriasis

Psoriasis is associated with an increased prevalence of co-morbidities affecting different organ systems (Figure 2), resulting in a decline in overall health and increased risk of early mortality.17 Aside from cutaneous lesions and associated co-morbidities, psoriasis has a significant impact on patients’ mental health and quality of life. Patients with psoriasis suffer a higher prevalence of depression, anxiety, and thoughts of suicide compared with patients in a general medical population.15 If complete resolution of psoriasis is achieved, improvements in self-consciousness, perceived quality of life measures, social activity, relationships, and sexual function occur.18 In a Phase 3 trial, patients who achieved 90% and 100% improvement in their PASI scores (PASI 90 and PASI 100, respectively) had improvements in quality of life measures that exceeded those of patients with 75–89% or less improvement in their PASI scores.19

disease state


Dermatologists provide the majority of patient treatment for psoriasis, with rheumatologists providing some overlapping treatment to patients with psoriatic arthropathy. For many years, providers treated patients with more severe disease with systemic drugs, such as cyclosporine and methotrexate, which had significant side effects and only partial, and often variable, efficacy.20 Advances in psoriasis therapy began with the approval of the tumor necrosis factor (TNF) inhibitor etanercept in 2004.21 Several TNF inhibitors were subsequently approved for moderate-to-severe disease, and initial treatment guidelines were published to assist the practitioner in management of the disease.

Advances in therapy have been associated with an increase in the ability to achieve complete clearance of psoriasis in patients (Figure 3). When methotrexate was the gold standard of treatment, achieving an improvement in baseline PASI of 50% (PASI 50) was considered “clinically meaningful,” and a 25% response (PASI 25) was considered “minimal.”22 With the approved use of  TNF inhibitors for the treatment of moderate-to-severe psoriasis, the primary clinical study objective was to achieve a 75% improvement from baseline PASI score (PASI 75). PASI 75 became the benchmark for adequate response in most studies.23-25 More recently, molecules that directly target the key cytokines IL-23 and IL-17A have been approved. These more specific, targeted therapies are associated with higher rates of near complete or complete skin clearance (PASI 90, PASI 100) than was previously possible with methotrexate.26,27 This has led to ongoing consideration of what the benchmark level of response should be (Figure 4).

PASI Improvement Scores

Before the 1990s, the primary unmet need for patients with psoriasis (especially in patients with moderate-to-severe disease) was developing drugs potent and safe enough to control patients’ disease. Now that more potent drugs with favorable safety profiles are available, these medications must be made available to patients in order to provide the best quality of care.

historical view

Guidelines for therapy selection are available from organizations such as the American Academy of Dermatology (Figure 5).28 In its mildest form, psoriasis can be managed with relatively low-cost therapies. Often, dermatologists treat patients with limited psoriasis with topical agents or phototherapy. However, for moderate-to-severe disease, which affects 20% of psoriasis patients, these solutions are neither very effective nor practical. Those with more extensive disease may receive phototherapy, systemic agents, or biologics.29

algorithm for treating psoriasis


The development of medications specifically targeting the inflammatory process associated with psoriasis has the potential to change the lives of patients with moderate-to-severe disease. However, cost remains an impediment for patients and the insurance companies that support them.

Unfortunately, it is not always easy to obtain medications that can lead to better outcomes. Payers currently utilize a number of strategies to encourage health care providers to select drugs that provide the best outcomes while minimizing the overall costs of treatment. These strategies include the application of evidence-based guidelines, increasing patient cost-sharing, requiring prior authorization, incorporating step-therapy protocols, and excluding some medications from coverage plans.30 When incorporating these strategies, the need to assure optimal treatment outcomes in a timely manner has not been a primary consideration. A recent review of patient surveys from the National Psoriasis Foundation over an 8-year period found that the inability to obtain adequate insurance coverage was among the top reasons for under-treatment and patient dissatisfaction for those with moderate-to-severe disease.31 As signs point to a future of health care in the United States in which treatment value is based on an emerging pool of high-quality evidence,32 present strategies will need to be reassessed for value. Such reassessments will likely reveal that higher initial treatment cost results in lower global costs in the long-term.

Given the associated comorbidities and the multi-faceted ways psoriasis impacts every aspect of a patient’s life, it is inappropriate to categorize this unique, debilitating condition beneath the larger rubric of inflammatory disease. Presently, biologic formularies and step-therapy decisions are often made based on market share, meaning that those agents with a greater number of indications, regardless of efficacy within a specific disease state, are the primary agents of choice.33 Hence, the needs of patients with psoriasis may not be met by policies and incentives that are largely derived from the care of disease states other than psoriasis (eg, rheumatoid arthritis). Such policies are unlikely to give patients with psoriasis optimal outcomes. Recent studies have demonstrated improved outcomes with newer, more targeted agents compared to a first generation TNF alpha antagonist.27,34,35


Formulary decision-makers, employers, and patients may benefit from consideration of pricing models beyond drug cost that include total cost for disease treatment, direct and indirect (additional provider visits, follow-up labs, quality of life, decreased work productivity, etc). As an example, a recent study considered the cost per patient to achieve PASI 75 and a minimally important difference in quality of life after 12 weeks of treatment. The authors utilized models that included medication dosage, route of administration, laboratory monitoring, and clinical visits per manufacturing guidelines. Non-medical costs and indirect costs to patients were not incorporated into the model. Prices were based on the wholesale price of the drug in 2010, and all FDA-approved biologics for psoriasis at that time were considered.36

With near-complete resolution (PASI 90) as an accepted improvement goal,37 the cost to achieve that goal using earlier biologics versus newer agents that specifically target psoriasis will need to be explored. The final cost to achieve a specific outcome is dependent on the number needed to treat (NNT) with an agent to achieve one such outcome. One pharmacoeconomic study examined the NNT to achieve PASI improvements of 75%, 90%, and 100% using four FDA-approved biologics. Though the study was limited by lack of PASI 100 data, there was a consistent increase in price to achieve greater levels of clearance using those agents.38 Understanding pharmacoeconomic implications of more effective treatments, including the relationship between cost and NNT, may be valuable as an alternative method of evaluation for medications used in psoriasis.


Significant breakthroughs in our understanding of psoriasis have led to a new generation of highly effective therapies. Treatments now exist to provide excellent outcomes, including complete clearance, for many patients with more severe disease. Given the high direct physical, mental, and social costs of this illness and given the potential indirect costs from co-morbid illness, psoriasis treatment decisions should not be made based primarily on disease states other than psoriasis. A formulary limited by decisions regarding the best treatment for inflammatory disorders (e.g. rheumatoid arthritis, Crohn’s disease) may not adequately address the needs of the psoriasis patient. 



1.    Van Voorhees A, Feldman SR, Koo JYM, Lebwohl MG, Menter A. The Psoriasis and Psoriatic Arthritis Pocket Guide, 3rd edition. 2015. Accessed Novermber 3, 2015.

2.    Parisi R, Symmons DP, Griffiths CE, Ashcroft DM, Identification and Management of Psoriasis and Associated ComorbidiTy (IMPACT) project team. Global epidemiology of psoriasis: a systematic review of incidence and prevalence. J Invest Dermatol. 2013;133(2):377–385.

3.    International Federation of Psoriasis Association. Profile of Psoriasis. Accessed November 3, 2015. 

4.    Huerta C, Rivero E, Rodriguez LA. Incidence and risk factors for psoriasis in the general population. Arch Dermatol. 2007;143(12):1559–1565.

5.    Tsoi LC, Spain SL, Knight J, et al. Identification of 15 new psoriasis susceptibility loci highlights the role of innate immunity. Nat Genet. 2012;44(12):1341–1348.

6.    Lowes MA, Kikuchi T, Fuentes-Duculan J et al. Psoriasis vulgaris lesions contain discrete populations of Th1 and Th17 T cells. J Invest Dermatol. 2008;128(5):1207–1211.

7.    Jariwala SP. The role of dendritic cells in the immunopathogenesis of psoriasis. Arch Dermatol Res. 2007;299(8):359–366.

8.    Piskin G, Sylva-Steenland RM, Bos JD, Teunissen MB. In vitro and in situ expression of IL-23 by keratinocytes in healthy skin and psoriasis lesions: enhanced expression in psoriatic skin. J Immunol. 2006;176(3):1908–1915.

9.    Fredriksson T, Pettersson U. Severe psoriasis—oral therapy with a new retinoid. Dermatologica. 1978;157(4):238–244.

10.    Yosipovitch G, Goon A, Wee J, Chan YH, Goh CL. The prevalence and clinical characteristics of pruritus among patients with extensive psoriasis. Br J Dermatol. 2000;143(5):969–973.

11.    Ljosaa TM, Stubhaug A, Mork C, Moum T, Wahl AK. Improvement in Psoriasis Area and Severity Index score predicts improvement in skin pain over time in patients with psoriasis. Acta Derm Venereol. 2013;93(3):330–334.

12.    Bhosle MJ, Kulkarni A, Feldman SR, Balkrishnan R. Quality of life in patients with psoriasis. Health Qual Life Outcomes. 2006;4:35.

13.    Daudén E, Castañeda S, Suárez C, et al. Clinical practice guideline for an integrated approach to comorbidity in patients with psoriasis. J Eur Acad Dermatol Venereol. 2013;27(11):1387–1404.

14.    McDonough E, Ayearst R, Eder L, et al. Depression and anxiety in psoriatic disease: prevalence and associated factors. J Rheumatol. 2014;41(5):887–896.

15.    Finlay AY, Coles EC. The effect of severe psoriasis on the quality of life of 369 patients. Br J Dermatol. 1995;132(2):236–244.

16.    Gelfand JM, Troxel AB, Lewis JD et al. The risk of mortality in patients with psoriasis: results from a population-based study. Arch Dermatol. 2007;143(12):1493–1499.

17.    Mattei PL, Corey KC, Kimball AB. Psoriasis Area Severity Index (PASI) and the Dermatology Life Quality Index (DLQI): the correlation between disease severity and psychological burden in patients treated with biological therapies. J Eur Acad Dermatol Venereol. 2014;28:333–337.

18.    Revicki DA, Willian MK, Menter A, Saurat JH, Harnam N, Kaul M. Relationship between clinical response to therapy and health-related quality of life outcomes in patients with moderate to severe plaque psoriasis. Dermatology. 2008;216(3):260–270.

19.    Brezinski EA, Dhillon JS, Armstrong AW. Economic burden of psoriasis in the United States: a systematic review. JAMA Dermatol. 2015;151(6):651–658.

20.    Warren RB, Smith RL, Campalani E, et al. Outcomes of methotrexate therapy for psoriasis and relationship to genetic polymorphisms. Br J Dermatol. 2009;160(2):438–441.

21.    Leonardi CL, Powers JL, Matheson RT, et al. Etanercept as monotherapy in patients with psoriasis. N Engl J Med. 2003;349(21):2014–2022.

22.    Carlin CS, Feldman SR, Krueger JG, Menter A, Krueger GG. A 50% reduction in the Psoriasis Area and Severity Index (PASI 50) is a clinically significant endpoint in the assessment of psoriasis. J Am Acad Dermatol. 2004;50(6):859–866.

23.    Gottlieb AB, Matheson RT, Lowe N, et al. A randomized trial of etanercept as monotherapy for psoriasis. Arch Dermatol. 2003;139(12):1627–1632.

24.    Gordon KB, Langley RG, Leonardi C, et al. Clinical response to adalimumab treatment in patients with moderate to severe psoriasis: double-blind, randomized controlled trial and open-label extension study. J Am Acad Dermatol. 2006;55(4):598–606.

25.    Reich K, Nestle FO, Papp K, et al. Infliximab induction and maintenance therapy for moderate-to-severe psoriasis: a phase III, multicentre, double-blind trial. Lancet. 2005;366(9494):1367–1374.

26.    Papp KA, Langley RG, Lebwohl M, et al. Efficacy and safety of ustekinumab, a human interleukin-12/23 monoclonal antibody, in patients with psoriasis: 52-week results from a randomised, double-blind, placebo-controlled trial (PHOENIX 2). Lancet. 2008;371(9625):1675–1684.

27.    Langley RG, Elewski BE, Lebwohl M, et al. Secukinumab in plaque psoriasis—results of two phase 3 trials. N Engl J Med. 2014;371:326–338.

28.    The American Academy of Dermatology. Treatment of Psoriasis Decision Tree. Accessed November 3, 2015.

29.    Menter A, Gottlieb A, Feldman SR, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis. J Am Acam Dermatol. 2008;58(5):826–850.

30.    Pharmaceutical Strategies Group. Understanding Specialty Pharmacy Management and Cost Control. Accessed November 3, 2015.

31.    Armstrong AW, Robertson AD, Wu J, Schupp C, Lebwohl MG. Undertreatment, treatment trends, and treatment dissatisfaction among patients with psoriasis and psoriatic arthritis in the United States: findings from the National Psoriasis Foundation surveys, 2003-2011. JAMA Dermatol. 2013;149(10):1180–1185.

32.    McCauley JL. Guidelines and value-based decision making: an evolving role for payers. N C Med J. 2015;76(4):243–246.

33.    U.S. payers intend to limit preferred coverage to only one immune biologic [press release]. PR Newswire; August 6, 2009. Accessed November 3, 2015.

34.    Goren A, Carter C, Lee S. Patient reported health outcomes and non-adherence in psoriasis patients receiving adalimumab or ustekinumab for moderate to severe plaque psoriasis. J Dermatolog Treat. 2015;19:1–8.

35.    Griffiths CE, Reich K, Lebwohl M, et al. Comparison of ixekizumab with etanercept or placebo in moderate-to-severe psoriasis (UNCOVER-2 and UNCOVER-3): results from two phase 3 randomised trials. Lancet. 2015;386(9993):541–551.

36.    Ahn CS, Gustafson CJ, Sandoval LF, Davis SA, Feldman SR. Cost effectiveness of biologic therapies for plaque psoriasis. Am J Clin Dermatol. 2013;14(14):315-326.

37.    Puig L. PASI90 response: the new standard in therapeutic efficacy for psoriasis. J Eur Acad Dermatol Venereol. 2015;29(4):645–648.

38.    Foster SA, Zhu B, Al Sawah S. Cost per additional responder associated with biologic use in psoriasis [PSY31-Q7]. Poster presented at: International Society for Pharmacoeconomic Research 20th Annual International Meeting; May 16-20, 2015; Philadelphia, PA.