Table 2: Newer epidemiological surveys of PDDs.

References	Country	Size	Age	Prevalence/10,000	95% CI
Baird et al, 2000 (58)	UK	16,235	7	57.9	46.8 – 70.9
Bertrand et al, 2001 (60)	USA	8,896	3-10	67.4	51.5 – 86.7 *
Chakrabarti & Fombonne, 2001 (37)	UK	15,500	4-7	61.9	50.2 – 75.6
Madsen et al, 2002 (11)	Denmark	---	8	30.0	---
Scott et al, 2002 (70)	UK	33,598	5-11	58.3 *	50 -67 *
Yeargin-Allsopp et al, 2003 (72)	USA	289,456	3-10	34.0	32 – 36
Gurney et al, 2003 (8)	USA	---	8 – 10	52.0 † 66.0	--- ---
Icasiano et al, 2004 (73)	Australia	≈ 54,000	2-17	39.2	---
Tebruegge et al., 2004 (62)	UK	2,536	8-9	82.8	51.3 – 126.3
Chakrabarti & Fombonne, 2005 (38)	UK	10,903	4-6	58.7	45.2 – 74.9
Baird et al, 2006 (20)	UK	56,946	9-10	116.1	90.4 – 141.8
Fombonne et al, 2006 (9)	Canada	27,749	5–17	64.9	55.8 – 75.0
Harrison et al, 2006 (34)	UK	134,661	0-15	44.2‡	39.5 – 48.9
Gillberg et al, 2006 (69)	Sweden	32,568	7 12	80.4	71.3 – 90.3
CDC, 2007a (12)	USA	187,761	8	67.0	---§
CDC, 2007b (13)	USA	407,578	8	66.0	63 – 68
Ellefsen et al, 2007 (66)	Denmark	7,689	8-17	53.3	36 – 70
Latif & Williams, 2007 (68)	UK	39,220	0-17	61.2	54 – 69 *
Wong et al, 2008 (74)	China	4,247,206	0-14	16.1 (1986-2005) 30.0 (2005)	--- ---
Nicholas et al, 2008 (75)	USA	47,726	8	62.0	56 – 70
Kawamura et al, 2008 (21)	Japan	12,589	5-8	181.1	158.5 – 205.9 *
Williams et al, 2008 (69)	UK	14,062	11	61.9	48.8 – 74.9
Lazoff et al, 2009 (9)	Canada	23,662	5-17	80.3	68.9-91.7

^*calculated by the author

^†these are the highest prevalences reported in this study of time trends. The prevalence in 10 year olds is for the 1991 birth cohort, and that for 8 year olds for the 1993 birth cohort. Both prevalences were calculated in the 2001-2002 school year.

^‡estimated using a capture-recapture analysis, the number of cases used to calculate prevalence was estimated to be 596.

^§specific values for % with normal IQ and confidence intervals are available for each state prevalence