ERA

Question 1

ILAR definition of ERA

Answer 1

Arthritis and enthesitis or
Arthritis or enthesitis with at least 2 of the following
- SI joint tenderness and or inflammatory lumbosacral pain
- Presence of HLA B27
- Onset of arthritis in a boy after 6 years of age
- Family history of HLA B27 associated disease in a first degree relative
- Acute anterior symptomatic uveitis

Question 2

Exclusion criteria

Answer 2

Presence of IgM RF
Psoriasis in patient or first degree relative
Systemic JIA
Arthritis fulfilling two JIA categories

Question 3

ERA includes

Answer 3

1. JAS–> HLA B27 positive and axial disease
2. SEA–> seronegative enthesitis and arthritis (neg ANA and RF), may be HLA B27 positive
3. JpSA–> HLA b27 and axial involvement

Question 4

New York criteria for diagnosis AS

Answer 4

Clinical Criteria

1. Limitations in spinal motion in all three planes
2. Unable to expand chest past 2.5 cm at the level of the 4th intercostal
3. Pain or history of pain at the dorsolumbar junction or lumbar spine

Definite AS- Grade 3-4 b/l SI on X ray with at least one clinical criteria OR Grade 3-4 unilaterally or grade 2 B/l with clinical criteria one or 2 and 3

Probable: Grade 3-4 b/l SI arthritis without clinical criteria

Question 5

Heritablity due to HLA b27

Answer 5

20 percent

Question 6

Risk of developing some form of SpA in an HLA b27 positive individual

Answer 6

around 5%

Question 7

Penetrance of an individual with a familial AS inheritance of autosomal dominant pattern

Answer 7

20 percent

Question 8

3 theories by which HLA B27 promotes disease

Answer 8

1. Molecular mimicry–> HLA b27 is targeted by Cd8 T cells because it presents self peptides that resemble peptides from micro organisms
2. Misfolding in the ER leads to activation of inflammatory cascade, can lead to overproduction of Il23
3. HLA B27 expression can render cells defective in killing intracellular bacteria

Question 9

Most common sites for enthesitis

Answer 9

Insertonal sites of the patella (10, 2 and 6)

Heel and plantar fascial attachments to the heads of the metatarsals

Question 10

Predictors of progression to AS

Answer 10

HLA B27
DRB1*04
Male sex
older age at onset of symptoms 
family history of AS
Arthritis 
Poly arthritis 
enthesitis 
tarsi's 
hip involvement 
early axial involvement 
Psoriasis

Question 11

Schober test

Answer 11

Draw a line connecting the dimples of Venus
Draw a vertical line 5 cm below, and ten cm above
Have them bend over
Measurement of less than 6 cm is abnormal (going from 15 to 21)

Question 12

What is considered abnormal chest expansion?

Answer 12

Any thoracic excursion of less than 5 cm (max expiration to max inspiration measured at the 4th intercostal space) is abnormal

Question 13

Poor prognostic factors associated with a failure to achieve remission

Answer 13

Presence of AS In first degree relative
HLA DRB1*08, ankle or hip arthritis within the first 6 months of onset, development of SI and persistently elevated inflammatory markers with the first 6 months of disease onset

Question 14

Poor prognostic factors associated with poor physical health

Answer 14

Female sex
Family history of AS
High number of affected joints within the first 6 months of onset

Question 15

Risk of a heterozygous HLA B27 positive parent with AS having a male child with disease if they HLA B27 negative or positive

Answer 15

If negative, 5-10 percent, if positive 20%

Question 16

Tarsitis

Answer 16

Occurs in 1/3

Results in characteristic forefoot adduction deformity