The influence of heredity for psoriasis on the ILAR classification of juvenile idiopathic arthritis.
OBJECTIVE
To evaluate how heredity for psoriasis influences classification according to the International League of Associations for Rheumatology (ILAR). Heredity for psoriasis is currently both an exclusion and an inclusion criterion for different types of childhood arthritis according to ILAR classification criteria.


METHODS
Twenty physicians in 5 Nordic countries prospectively collected data from the incident cases in their catchment areas over an 18 month period beginning July 1, 1997. Clinical and serological data from the first year of disease were collected.


RESULTS
Of the 321 patients included who could be classified according to ILAR criteria for childhood arthritis, 50 (15.6%) patients were excluded from 55 classification events and fulfilled criteria for "other arthritis 1" i.e., did not fulfill criteria for any of the other classification categories, primarily because of heredity for psoriasis. If psoriasis in second degree relatives was disregarded as an exclusion criterion, only 8.7% of the patients remained in the "other arthritis 1" subgroup. For 20.6% of the whole group, heredity for psoriasis in a first or second degree relative (or both) and its distribution among arthritis subgroups did not differ except for juvenile psoriatic arthritis.


CONCLUSIONS
We suggest that second degree heredity for psoriasis be withdrawn as an exclusion criterion from the ILAR criteria.
Berntson
Lillemor
L
Department of Pediatrics, Falun Hospital and Göteborg University, Göteborgm, Sweden. lillemor.bernston@falun.mail.telia.com
Fasth
Anders
A
Andersson-Gäre
Boel
B
Herlin
Troels
T
Kristinsson
Jon
J
Lahdenne
Pekka
P
Marhaug
Gudmund
G
Nielsen
Susan
S
Pelkonen
Pirkko
P
Rygg
Marite
M
D001171:Arthritis, Juvenile / Q000145:classification* / Q000235:genetics*; D015535:Arthritis, Psoriatic / Q000145:classification* / Q000235:genetics*; D002648:Child; D015331:Cohort Studies; D006801:Humans; D011446:Prospective Studies