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Supplements Easing the Economic and Clinical Burden of Psoriasis and Psoriatic Arthritis: The Role of Managed Ca

Psoriasis and Psoriatic Arthritis Overview

Alan Menter, MD
the presence and severity of each of 3 components of psoriatic plaques (erythema, induration, and desquamation) within each of 4 regions of the body (head/neck, trunk, upper extremities, and lower extremities). Second, clinicians estimate the extent of skin involvement by assigning a grade from 0 (no psoriasis) to 6 (90%-100% involvement) to estimate the BSA within each of the 4 body regions. Utilizing a complex algorithm, the individual scores are used to calculate a total PASI score that can range from 0 to 72. In real-world clinical practice, PASI scores higher than 36 are rare.8

     Critics of the PASI argue that the tool does not correspond well with the patient’s experience of psoriasis severity. The PASI algorithm assigns equal weight to lesions occurring anywhere on the body; however, plaques that affect the face, hands, and anogenital area are considered by patients to be more severe than those located elsewhere.8 Furthermore, the PASI does not capture other aspects of psoriasis that are important to patients. When patients with psoriasis (N = 1005) were asked to rank the top 5 most important factors contributing to disease severity, more than one-third (36.1%) ranked itching as the most important factor. Additional factors included location/size of lesions (21.8%), flaking (11.4%), scaling (8.3%), and pain/swelling of joints (5.4%). Despite being the most important symptom for many patients, itching is not captured in the PASI or other instruments such as the Physician Global Assessment. Therefore, current tools may underestimate the true burden of psoriasis on patients.6

     New options for assessing the severity of psoriasis, with an emphasis on patient-reported outcomes, have recently been implemented. These tools facilitate an improved understanding of the impact of psoriasis on patients’ lives, and provide better instruments for measuring the efficacy of powerful new treatments in clinical practice.8

Differential Diagnosis

     Not all cases of psoriasis present with characteristic erythematous, scaling, or silvery plaques. When lesions are misleading, the differential diagnosis of psoriasis can be challenging, and it may vary by psoriasis subtype.Plaque type psoriasis is often confused with eczema, fungal infections such as tinea corporis, squamous cell carcinoma (Bowen’s disease), cutaneous T-cell lymphoma

(CTCL) and subacute cutaneous lupus erythematous.Pustular psoriasis should be differentiated from candidiasis and acute generalized exanthematic pustulosis. Guttate psoriasis can appear similar to secondary syphilis or pityriasis rosea. Erythrodermic psoriasis should be differentiated from pityriasis rubra pilaris, Sézary syndrome, drug eruptions, and even Norwegian scabies. Finally, inverse

psoriasis can have a similar presentation to intertrigo, candidiasis, or tinea cruris.3

Comorbidities

     
Patients with psoriasis, particularly those who are already burdened with moderate to severe skin disease and those with PsA, face a high risk of comorbidities.Approximately 75% of patients with psoriasis have at least 1 comorbid condition.6

      
A recent analysis of a large US administrative claims database revealed the scope and prevalence of comorbidities in patients with psoriasis. The study compared healthcare utilization patterns among patients with moderate to severe psoriasis (N = 5492) and controls without psoriasis or PsA matched by age, gender, and geographic region (N = 5492). The most common comorbidities in patients with psoriasis were cardiometabolic risk factors such as hyperlipidemia, hypertension, and diabetes. These, as well as multiple other comorbidities including obesity and the metabolic syndrome, occurred with significantly greater frequency among patients with psoriasis than among controls. Hyperlipidemia was present in 33% versus 27%, hypertension in 33% versus 24%, and diabetes in 16% versus 10% of psoriasis versus non-psoriasis patients, respectively; in addition, 22.1% of patients with psoriasis also had a diagnosis of PsA.10

     Given their high burden of comorbidities, patients with psoriasis have many interactions with the healthcare system. During the 12-month study period, patients with psoriasis were more likely than individuals without psoriasis to have any prescription medications filled (98.8% vs 76.6%; odds ratio [OR], 27.5; P <.001) and had a higher number of distinct medications filled (10.9 vs 5.2; incident

rate ratio [IRR], 2.1; P <.001). In addition to utilizing a range of psoriasis treatments, including biologic therapy (65.2%), nonbiologic systemic therapy (27.3%), and phototherapy (16.5%), patients with psoriasis were more likely than controls to fill prescriptions for antidepressants (25% vs 13.9%; OR, 2.1; P <.001), antidiabetic drugs (11.3% vs 6.8%; OR, 1.7%; P <.001), and cardiovascular drugs (47.9% vs 36.1%; OR, 1.7%; P <.001). Furthermore, patients with psoriasis were significantly more likely than non-psoriasis controls to utilize medical services during the 12-month observational period. This included a higher likelihood of outpatient visits (99.0% vs 84.5%; OR, 29.3; P < .001), emergency department visits (21.4% vs 16.4%; OR, 1.3; P <.001), and hospital admissions (9.3% vs 6.4%; OR, 1.3; P = .001).10 These findings highlight the economic implications of comorbidity management in patents with psoriasis.

Patient Expectations

     In addition to having medical comorbidities, patients with psoriasis may experience a range of profound psychosocial and behavioral challenges throughout the course of their disease. Each life stage is associated with a different mix of predominant concerns from the patient’s perspective (Table 111). The optimal management of psoriasis should address all aspects of disease burden through appropriate interventions or referrals.11

Quality of Life

     Across the lifespan, quality of life is of particular concern. Patients with moderate to severe psoriasis commonly report negative social, emotional, and other life experiences that they attribute to their disease. Suicidal ideation is significantly increased in younger psoriasis patients. Table 212 describes the scope and frequency of these adverse experiences. Addressing these patient-reported outcomes is a key component of comprehensive psoriasis care.12

Treatment

     Psoriasis management has undergone a major paradigm shift from older therapies to newer biologic agents. With this change in focus, managed care organizations face new challenges in balancing the benefits, limitations, and pharmacoeconomics of current and emerging therapies. See Part 2 of this continuing education supplement for a review of current local and systemic options for psoriasis treatment.

PSORIATIC ARTHRITIS OVERVIEW

     PsA is an underdiagnosed and undertreated inflammatory joint disease that develops in a substantial minority of patients with psoriasis. Although the clinical course is variable, many patients with PsA can experience progressive joint disease, impaired physical function, and decreased quality of life.13

Prevalence and Epidemiology

     Among patients with psoriasis, the prevalence of PsA in recent US cohort studies ranged from 22% to 27%.6,10 Overall, PsA affects approximately 0.1% to 0.2% of the general population.14 The clinical manifestations of PsA tend to emerge 5-12 years after initial skin presentation (ie, between the ages of 30 and 50 years in affected individuals). As with psoriasis, men and women are equally likely to develop PsA.15

Pathophysiology

     
Although the etiology of PsA remains still to be completely understood, multiple immune system cell types and cytokines have been implicated in PsA disease activity.14,15 The synovial fluid of joints affected by PsA shows increased levels of T-cells and cytokines such as TNF, IL-6, IL-12/IL-23, and IL-17.15 Together, these cytokines drive joint inflammation and other downstream biological effects, such as osteoblast and osteoclast activation, which further contributes to joint damage.16 Biologic therapies targeting these aberrant signaling pathways have emerged as key treatment options for PsA, particularly for patients with moderate to severe disease.13

Presentation and Prognosis

     The classic clinical manifestations of PsA include swelling, tenderness, stiffness, and pain of the joints and surrounding tissues.15 Dactylitis (“sausage digit”) is a hallmark feature of PsA that involves swelling of the joints, tendons, ligaments, and synovial tissue in the hands and/or feet (Figure 7).15,17 Enthesitis is tenderness and swelling where tendon, ligament, or joint capsule fibers insert into the bone; it is particularly common within the plantar fascia, Achilles’ tendons, ribs, spine, and pelvis (Figure 8).15

      
Joint involvement in PsA can include peripheral and/or axial joints. Most patients (95%) show some degree of peripheral joint involvement, whereas only 5% have exclusively axial joint involvement (spondyloarthritis). Up to 50% of patients with PsA will have symptoms in both the spine and peripheral joints. In addition to experiencing joint symptoms, approximately 90% of patients with PsA will exhibit characteristic psoriatic nail disease, particularly in those with distal interphalangeal involvement.1 Of note, there is no correlation between the severity of skin and joint symptoms in PsA. Patients with PsA may have very mild skin disease with severe arthritis, or vice versa.15

     The clinical course of PsA is characterized by a series of remissions and disease flares, with fewer than 20% of patients experiencing prolonged remissions.13 Prognosis is unpredictable and varies from mild joint disease to severe and debilitating outcomes.15 Approximately 25% to 30% of patients will experience relatively benign joint inflammation, with limited disability over time. For up to 60% of patients, however, PsA is associated with progressive, erosive, and deforming joint damage. Severely deforming arthritis (arthritis mutilans) affects approximately 5% of patients with PsA.17

     One of the major barriers to improved prognosis involves widespread undertreatment.6 Many patients with PsA do not receive the recommended systemic therapies to slow disease progression.13 In the Multinational Assessment of Psoriasis and Psoriatic Arthritis (MAPP) survey (N = 1005), only half of patients were being treated with conventional oral therapy (24%) or biologic therapy (26%) to address their joint symptoms.6 Without recommended treatment, a significant portion of patients with PsA will experience ongoing systemic inflammation, progressive joint damage, severe disability, multiple comorbidities, and increased mortality.15,18-20

Diagnosis

 
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