The incidence of immune thrombocytopenic purpura in children and adults: A critical review of published reports.

Reports of the incidence of ITP are few and their methodology is variable. Accurate estimates of the incidence of immune thrombocytopenic purpura (ITP) are important to understand the medical and public health impact of the disease. To critically review all published reports on the incidence of ITP in children and adults, all articles identified on the Medline database (searched January 1, 1966-August 7, 2009) that reported data on the incidence of ITP were retrieved. Articles which directly estimated the incidence of ITP were selected for review. Eight articles reported the incidence of acute ITP in children. After review, four were determined to have the strongest estimates, based on the method of patient identification and study design. The lowest incidence estimate in these four studies was 2.2 per 10(5) children/year (95% confidence interval 1.9, 2.4) and the highest incidence estimate was 5.3 per 10(5) children/year (95% confidence interval 4.3, 6.4). Three studies reported the incidence of ITP in adults. The estimate from the article with the strongest methodology reported an incidence estimate of 3.3 per 10(5) adults/year. The current strongest estimate of the incidence of acute ITP in children is between 1.9 and 6.4 per 10(5) children/year; for adults the current strongest estimate of the incidence of ITP is 3.3 per 10(5) adults/year. An important limitation of these studies is that they are primarily from Europe and may not be generalizable to all regions.