Table 2.

Comparison of ITP period prevalence estimates by age categories and years of data^*

Patients	10-year period prevalence 1995–2004	5-year period prevalence 2000–2004	2-year period prevalence 2003–2004	Average annual prevalence**
Children <16 years	43.6 (39.0, 48.2)	27.4 (23.7, 31.1)	13.6 (11.1, 16.2)	8.1 (6.7, 9.5)
Adults ≥16 years	30.6 (28.5, 32.7)	26.9 (24.9, 28.8)	19.3 (17.6, 21.0)	12.1 (11.1, 13.0)
All Patients	33.2 (31.3, 35.2)	26.7 (25.0, 28.5)	18.0 (16.6, 19.4)	11.2 (10.4, 12.0)

^*Prevalence estimates, with 95% confidence intervals in parentheses, are per 100,000 children for children, per 100,000 adults for adults, and per 100,000 population for all patients.

^**Average annual prevalence was calculated from the 2003 and 2004 one-year ITP prevalence estimates.