Childhood idiopathic thrombocytopenic purpura in the Nordic countries: epidemiology and predictors of chronic disease.
OBJECTIVE
To describe the epidemiology of idiopathic thrombocytopenic purpura (ITP) in the Nordic countries, to define clinical subgroups and to investigate factors predicting chronic disease.


METHODS
A prospective registration was done from 1998 to 2000, including all children with newly diagnosed ITP aged 0-14 y and at least one platelet count <30 x 10(9)/l.


RESULTS
506 children were registered and 423 followed for 6 mo. The incidence was 4.8/10(5) per year. Most children were aged 0-7 y (78%), with a predominance of boys, while patients aged 8-14 y had equal representation of the two sexes. There were seasonal variations determined by variations in postinfectious cases with sudden onset. The platelet count was <10 x 10(9)/l in 58%, but bleeding manifestations were mild or moderate in 97%. The insidious form (symptoms for more than 2 wk) was more frequent in older children and girls, showed little seasonal variation, had milder manifestations and ran a chronic course in more than half the cases. Intracranial haemorrhages did not occur in the first 6 mo after diagnosis. Chronic ITP developed in 25%. The strongest predictor of chronic disease was insidious onset of symptoms (OR 5.97).


CONCLUSIONS
In the Nordic countries, ITP mainly affects children aged 0-7 y, with a winter bulk of postinfectious cases superimposed on a steady occurrence of non-infectious cases. Clinically, it may be useful to distinguish between children with sudden versus insidious onset of symptoms rather than between different age groups.
Paediatric Department of National Hospital of Norway, Oslo, Norway. bem.zeller@rikshospitalet.no
Bernward
B
Zeller
Jukka
J
Rajantie
Iris
I
Hedlund-Treutiger
Ulf
U
Tedgård
Finn
F
Wesenberg
Olafur G
OG
Jonsson
Jan Inge
JI
Henter
D000208:Acute Disease / Q000453:epidemiology; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease / Q000453:epidemiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D006470:Hemorrhage / Q000453:epidemiology / Q000209:etiology; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011379:Prognosis; D011446:Prospective Studies; D016553:Purpura, Thrombocytopenic, Idiopathic / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology*; D012307:Risk Factors; D012537:Scandinavian and Nordic Countries / Q000453:epidemiology; D018709:Statistics, Nonparametric