Discover PsA

Psoriatic Arthritis (PsA): A Distinct, Complex Disease

Psoriatic arthritis is characterized by stiffness, pain, swelling, and tenderness of the joints and surrounding ligaments and tendons5

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Psoriatic Arthritis Is a Chronic Peripheral Spondyloarthritis5

Psoriatic arthritis is often associated with psoriasis of the skin or nails.5 PsA is characterized by stiffness, pain, swelling, and tenderness of the joints and surrounding ligaments and tendons. Common findings include enthesitis (inflammation of the tendon insertion points on bone) and dactylitis (inflammation of the fingers).5 Severity of disease ranges from mild synovitis to severe, erosive arthropathy.5

≈ 85% of patients with PsA were first diagnosed with PsO6

PsA may develop in up to 30% of patients with PsO7

Undiagnosed PsA was present in 29% of PsO patients enrolled in a single-center dermatology study8

According to estimates, up to ≈750,000 people in the US are living with psoriatic arthritis. It is believed that many cases remain misdiagnosed or undiagnosed.9

According to the recent PsO and PsA survey of the NPF, 31.4% of patients with moderate psoriasis and 46.4% with severe psoriasis also suffered from PsA.10

A multicenter study that recruited 1122 dermatology clinic patients with active PSA found that nearly a quarter of these patients had received their diagnosis of PsA less than a year before baseline.11 This observation suggests that PsA may be under-recognized and undertreated in the general population. Gottlieb et al postulated that the joint disease may have been masked by the severity of the skin disease in these patients.11

Etiology of Psoriatic Arthritis

About 15% of the relatives of an index patient with PsA will also have PsA, and an additional 30% to 45% will have psoriasis.12 Susceptibility to PsA seems to be specified by genes of the class I major histocompatibility complex (MHC), notably HLA-B and HLA-C.12, 13 HLA antigens have also been identified as prognostic markers for the progression of clinical damage in PsA.13 Given the high degree of familial aggregation and the overall heritability of PsA, HLA genes presumably account for only a portion of genetic susceptibility; non-MHC genes may also contribute to the development of PsA.12

Psoriatic Arthritis Is a Distinct Disease

Since at least 1973, when Moll and Wright proposed their subgroups for psoriatic arthritis,16 there has been an ongoing discussion about the classification of the disease.17, 18, 19 The classical description of PsA diagnostic criteria include 5 clinical patterns:18

  • Distal interphalangeal (DIP) arthritis
  • Arthritis mutilans
  • Symmetrical polyarthritis
  • Oligoarticular arthritis
  • Ankylosing spondylitis

Although these criteria are frequently used, they have considerable overlap.18 Furthermore, patterns in disease presentation may change over time; thus, the pattern at presentation may not be useful for classification.13

The typical features of psoriatic arthritis are19, 20:

Clinical Laboratory Radiographic

Psoriasis of skin or nails

Peripheral arthritis

Distal interphalangeal involvement

Dactylitis

Enthesopathy

Absence of rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA)*

Elevated acute phase markers

Erosion and resorptions

Joint space narrowing or involvement of entheseal sites

Bony spurs

Sacroiliitis

* Low levels of RF and ACPA can be found in 5% to 16% of patients20
‡ One study found sacroiliitis in 20% of PsA patients18

Clinical

Psoriasis of skin or nails

Peripheral arthritis

Distal interphalangeal involvement

Dactylitis

Enthesopathy

Laboratory

Absence of rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA)*

Elevated acute phase markers

Radiographic

Erosion and resorptions

Joint space narrowing or involvement of entheseal sites

Bony spurs

Sacroiliitis

* Low levels of RF and ACPA can be found in 5% to 16% of patients20
‡ One study found sacroiliitis in 20% of PsA patients18

Psoriatic arthritis is just one form of spondyloarthritis (SpA). Other subtypes of SpA include ankylosing spondylitis, arthritis/spondylitis with inflammatory bowel disease, reactive arthritis, and undifferentiated spondyloarthritis.21

A Comparison of Typical Features of Psoriatic Arthritis to Rheumatoid Arthritis, Osteoarthritis, and Ankylosing Spondylitis5

PsA RA OA AS
Peripheral disease Asymmetric Symmetric Asymmetric No
Sacroiliitis Asymmetric No No Symmetric
Stiffness In the morning and/or with immobility In the morning and/or with immobility With activity Yes
Female : male ratio 1:1 3:1 Hand/foot more common in female patients 1:3
Enthesitis Yes No No No
High-titer RF No Yes No No
HLA association CW6, B27 DR4 No B27
Nail lesions Yes No No No
Psoriasis Yes Uncommon Uncommon Uncommon

AS, ankylosing spondylitis; OA, osteoarthritis; PsA, psoriatic arthritis; RA, rheumatoid arthritis; RF, rheumatoid factor

PsA RA
Peripheral disease Asymmetric Symmetric
Sacroiliitis Asymmetric No
Stiffness In the morning and/or with immobility In the morning and/or with immobility
Female:male ratio 1:1 3:1
Enthesitis Yes No
High-titer RF No Yes
HLA association CW6, B27 DR4
Nail lesions Yes No
Psoriasis Yes Uncommon

PsA, psoriatic arthritis; RA, rheumatoid arthritis; RF, rheumatoid factor

PsA OA
Peripheral disease Asymmetric Asymmetric
Sacroiliitis Asymmetric No
Stiffness In the morning and/or with immobility With activity
Female:male ratio 1:1 Hand/foot more common in female patients
Enthesitis Yes No
High-titer RF No No
HLA association CW6, B27 No
Nail lesions Yes No
Psoriasis Yes Uncommon

OA, osteoarthritis; PsA, psoriatic arthritis; RF, rheumatoid factor

PsA AS
Peripheral disease Asymmetric No
Sacroiliitis Asymmetric Symmetric
Stiffness In the morning and/or with immobility Yes
Female:male ratio 1:1 1:3
Enthesis Yes No
High-titer RF No No
HLA association CW6, B27 B27
Nail lesions Yes No
Psoriasis Yes Uncommon

AS, ankylosing spondylitis; PsA, psoriatic arthritis; RF, rheumatoid factor

Although psoriatic arthritis and rheumatoid arthritis may share some features, the asymmetric joint involvement, spinal involvement, and nail and/or skin involvement that often occur in PsA are uncommon in RA.5, 22 Unlike RA, PsA is seronegative (ie, not associated with serum rheumatoid factor); and the two disorders are thought to have a different pathophysiology.5 Immunological comparisons of synovial fluid samples taken from the inflamed joints of patients (PsA, n = 15; RA, n = 33) suggest a different environment of proinflammatory cytokines in PsA versus RA.23

Despite its distinctive characteristics, PsA is widely under-recognized and undertreated8, leaving patients at risk of cumulative comorbidities and severe erosive joint damage, which can greatly impact quality of life and reduce work-related productivity.9

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References:

  • 1 Husted JA, Tom BD, Farewell VT, et al. A longitudinal study of the effect of disease activity and clinical damage on physical function over the course of psoriatic arthritis: Does the effect change over time? Arthritis Rheum. 2007;56(3):840‑849.
  • 2 Kane D, Stafford L, Bresnihan B, FitzGerald O. A prospective, clinical and radiological study of early psoriatic arthritis: an early synovitis clinic experience. Rheumatology (Oxford). 2003;42(12):1460‑1468.
  • 3 Brockbank JE, Stein M, Schentag CT, Gladman DD. Dactylitis in psoriatic arthritis: a marker for disease severity? Ann Rheum Dis. 2005;64(2):188‑190.
  • 4 Yamamoto T. Psoriatic arthritis: from a dermatological perspective. Eur J Dermatol. 2011;21(5):660‑666.
  • 5 Gottlieb A, Korman NJ, Gordon KB, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: Section 2. Psoriatic arthritis: overview and guidelines of care for treatment with an emphasis on the biologics. J Am Acad Dermatol. 2008;58:851‑864.
  • 6 National Psoriasis Foundation. Diagnosing psoriatic arthritis. http://www.psoriasis.org/ psoriatic‑arthritis/diagnosis. Accessed September 16, 2013.
  • 7 Boehncke WH, Adebajo A, Cauli A, et al. Initiative for quality in psoriasis and psoriatic arthritis. J Rheumatol. 2008 Jul;35(7):1431‑1433.
  • 8 Haroon M, Kirby B, FitzGerald O. High prevalence of psoriatic arthritis in patients with severe psoriasis with suboptimal performance of screening questionnaires. Ann Rheum Dis. 2013;72:736–740.
  • 9 Lee S, Mendelsohn A, Sarnes E. The burden of psoriatic arthritis: a literature review from a global health systems perspective. P T. 2010;35(12):680‑689.
  • 10 Armstrong AW, Robertson AD, Wu J, et al. Undertreatment, treatment trends, and treatment dissatisfaction among patients with psoriasis and psoriatic arthritis in the United States. JAMA Dermatol. doi:10.1001/jamadermatol.2013.5264.
  • 11 Gottlieb AB, Mease PJ, Mark Jackson J, et al. Clinical characteristics of psoriatic arthritis and psoriasis in dermatologists' offices. J Dermatolog Treat. 2006;17(5):279‑287.
  • 12 Fitzgerald O, Winchester R. Psoriatic arthritis: from pathogenesis to therapy. Arthritis Res Ther. 2009;11(1):214.
  • 13 Gladman DD. Psoriatic arthritis. Dermatol Ther. 2009 Jan‑Feb;22(1):40‑55.
  • 14 Pattison E, Harrison BJ, Griffiths CE, et al. Environmental risk factors for the development of psoriatic arthritis: results from a case‑control study. Ann Rheum Dis. 2008;67(5):672‑676.
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  • 16 Moll JMH, Wright V. Psoriatic arthritis. Semin Arthritis Rheum. 1973;3:55‑78.
  • 17 Gladman DD, Shuckett R, Russell ML, et al. Psoriatic arthritis (PSA)—an analysis of 220 patients. Q J Med. 1987 Feb;62(238):127‑141.
  • 18 Torre Alonso JC, Rodriguez Perez A, Arribas Castrillo JM, et al. Psoriatic arthritis (PA): a clinical, immunological and radiological study of 180 patients. Br J Rheumatol. 1991 Aug;30(4):245‑250.
  • 19 Helliwell PS, Taylor WJ. Classification and diagnostic criteria for psoriatic arthritis. Ann Rheum Dis. 2005;64(suppl 2):ii3‑ii8.
  • 20 Fitzgerald O. Psoriatic arthritis. In: Firestein GS, et al. Kelley's Textbook of Rheumatology. 8th ed. Philadelphia, PA: WB Saunders Co; 2008.
  • 21 Rudwaleit M, van der Heijde D, Landewé R, et al. The development of Assessment of SpondyloArthritis international Society classification criteria for axial spondyloarthritis (part II): validation and final selection. Ann Rheum Dis. 2009;68(6):777‑783.
  • 22 Altman RD. Rheumatoid arthritis (RA). The Merck Manual for Healthcare Professionals. http://www.merckmanuals.com/ home/bone_joint_and_muscle_disorders/ joint_disorders/rheumatoid_arthritis_ra.html?qt=rheumatoid arthritis&alt=sh. Updated May 2013. Accessed September 12, 2013.
  • 23 Vandooren B, Noordenbos T, Ambarus C, et al. Absence of a classically activated macrophage cytokine signature in peripheral spondylarthritis, including psoriatic arthritis. Arthritis Rheum. 2009 Apr;60(4):966‑75.
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