Australian Doctor Australian Doctor 15th December 2017 | Page 18

from page 16 arthritis . Disease is often subclinical .

Comorbidities Psoriasis and psoriatic arthritis are associated with obesity , type 2 diabetes , hypertension , metabolic syndrome and fatty liver . The presence of these co-factors is important , restricting treatment choices and blunting response to therapy in some subgroups . 14

Psoriatic arthritis imposes considerable morbidity on the affected patient . These include functional disability and psychological burden . 6

Juvenile psoriatic arthritis This is divided into two subtypes .

• Oligoarticular psoriatic arthritis is associated with uveitis and dactylitis , ANA positive , peak onset is in one- to two-year-olds and occurs predominantly in females .

• The second subtype ’ s peak onset is in 6-12-year-olds , has an equal gender distribution , is ANA negative , and is associated with dactylitis , enthesitis and axial involvement . 5

Joint pattern

Oligoarticular subtype

Four or fewer joints Asymmetrical Small and large joint

Table 2 . Subtypes of psoriatic arthritis

Polyarticular subtype

Symmetrical small and large joint

Sacroiliitis and spinal involvement

Severe involvement of DIP joints

Uncommon

Severe destructive / telescoping and flail digits

Rare

A . Pitting and discolouration of the nails .

Figure 4 . Symptoms of psoriatic arthritis

C and D . Ssausage finger and toe ( dactylitis )

B . Swollen finger joints

Normal

Affected

E . Sswollen heel at the Achilles tendon

Box 1 . Clinical features of the spondyloarthropathies The most commonly recognised joint manifestations are :

• Dactylitis – reported in 40-50 % of patients Prevalent second to third toes , may involve fingers . May be acute ( swelling , redness and pain ) or chronic ( swelling without pain ).

• Enthesitis – reported in 30-50 % of patients Achilles tendonitis ( bilateral or unilateral , recurrent ), involvement of patella ligament insertion , supraspinatus insertions , refractory epicondylitis

• Monoarthritis Typically large joint ; for example , chronic pain and swelling of the knee

• Oligaoarthritis Four or fewer joints , asymmetrical , small or large joint

• DIP involvement Usually associated with nail disease , can mimic primary generalised osteoarthritis ( PGOA )

• Symmetrical polyarthritis Acute or subacute onset of small- and large-joint polyarthritis

• Axial disease Sacroiliitis and / or spinal involvement 11

The clinical manifestations are represented in figure 4 .

F . Monoarthritis knee G . Axial symptoms

Figure 4 . Clinical manifestations of psoriatic arthritis Using these manifestations , five distinct presentations of psoriatic arthritis have been proposed ( see table 2 ). 12 It is essential to recognise that while these presentations are a useful guide , patients with psoriatic arthritis can exhibit a range of manifestations from each group and that the pattern can change in an individual over time . Adapted from : bit . ly / 2zrzMgl

THE classification criteria for psoriatic arthritis ( CASPAR ) provide a framework to assist in the diagnosis of psoriatic arthritis . 15 Psoriatic arthritis is likely if the score is equal to or greater than three . The CASPAR score parameters are presented in table 3 . 15

Clinical The diagnosis of psoriatic arthritis is based upon the recognition of clinical and imaging features . The personal and family history is important as this is helpful if it yields a positive finding in patients presenting with inflammatory joint pain . New onset morning joint stiffness , unexplained chronic knee swelling , refractory tendonitis ( enthesitis ) and dactylitis all provide important clues to the presence of the disease .

Psoriasis is often mild and has not been diagnosed previously . It is important to examine the nails ( pitting , hyperkeratosis ) and skin areas such as the hairline , postauricular region , natal cleft and umbilicus for any evidence of psoriasis .

Symptoms can often be present on a low fluctuating basis for months to years before an acute

episode brings the diagnosis to the surface .

Patient questionnaires Screening questionnaires developed for general practice and dermatologists have high sensitivity . 16 The major questionnaires are the PASE ( psoriatic arthritis and evaluation questionnaire ), the PEST ( psoriasis epidemiology screening tool ) and the EARP ( early arthritis for psoriatic patients ). Of the three , EARP ( see figure 5 ) is the fastest and simplest to administer and has high sensitivity and specificity . 17 A score of three or more indicates possible psoriatic arthritis and referral is recommended .

Table 3 . Classification Criteria for Psoriatic Arthritis ( CASPAR ) Criterion Explanation Points

Psoriasis

• Current

• Personal history

• Family history

• Current psoriatic skin or scalp disease

• History of psoriasis in the patient

• In a first- or second-degree relative

Rheumatoid factor negative

Dactylitis

• Current

• History of dactylitis

Radiographs – new bone formation

RF negative by ELISA or nephelometry

• Entire digit swelling on examination

• Confirmed on past history

Ossification near joint margins hands or feet

Psoriatic arthritis is considered to be present if score is more than or equal to 3 ( specificity 98.7 %, sensitivity 91.4 %).

18 | Australian Doctor | 15 December 2017 www . australiandoctor . com . au

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1

1

1 1

Questions Yes No

1 . Do your joints hurt ?

2 . Have you taken anti-inflammatory medication more than twice a week for joint pain in the last 3 months ? 3 . Do you wake up at night because of low back pain ? 4 . Do you feel stiffness in your hands for more than 30 minutes in the morning ? 5 . Do your wrists and fingers hurt ? 6 . Do your wrists and fingers swell ?

7 . Does one finger hurt and swell for more than 3 days ?

8 . Does your Achilles tendon swell ?

9 . Do your feet or ankles hurt ?

10 . Do your elbows or hips hurt ?

Score ( 1 point for every “ Yes ”)

Figure 5 . Early Arthritis for Psoriatic Patients ( EARP ) questionnaire . cont ’ d page 20