Table 1

Summary of prevalence studies of autism spectrum disorders (42 studies)

Ref.	Publ. year	First author	Country	Sample size	Area	Age (years)	Sample screened§	Screen methods¶	Prospective(P)/retrospective (R) assessment	Typical autism		All ASD
Ref.	Publ. year	First author	Country	Sample size	Area	Age (years)	Sample screened§	Screen methods¶	Prospective(P)/retrospective (R) assessment	Diagnostic criteria used	Prevalence estimate (per 10 000) (SE)	Diagnostic criteria used	Prevalence estimate (per 10 000) (SE)
Estimated from number of cases and prevalence estimate; †Cohort first screened at 18 months, followed up until age 7–8 years; ‡Data from an older cohort also included in the study, but excluded from these analyses; §Sample screened: P, whole population; C, general clinical services; S, specialist clinical/educational services; ¶Screen methods: C, routine checks; L, letter to elicit referrals; Q, questionnaires/interview; R, records (CHAT, Checklist for Autism in Toddlers; DAWBA, Development and Well-Being Assessment); *ICD-10 used for analysis; ††DSM-IV used for analysis.
14	1966	Lotter	UK	78 000	Urban	8–10	P	Q	P	Kanner	4.5 (0.76)	–	–
15	1970	Treffert	USA	899 750	Mixed	0–12	C	R	R	Kanner	0.7 (0.09)	–	–
16	1970	Brask	Denmark	46 500	Urban	2–14	S	–	–	Kanner	4.3 (0.96)	–	–
17	1979	Wing	UK	35 000	Urban	0–15	C	R	P	Kanner	4.9 (1.18)	Triad	21.2 (2.46)
18	1982	Hoshino	Japan	609 848	Mixed	0–18	P	L	P	Kanner	2.33 (0.20)	–	–
19	1983	Ishii	Japan	34 987	Urban	6–12	P	L	P	Rutter	16.0 (2.14)	–	–
20	1983	Bohman	Sweden	69 000	Mixed	0–20	P	L	P	Rutter	3.0 (0.66)	Rutter	5.6 (0.9)
21	1984	McCarthy	Ireland	65 000	Mixed	8–10	S	R	R	Kanner	4.3 (0.81)	–	–
22	1984	Gillberg	Sweden	128 584	Mixed	4–18	P	L	P	Rutter	2.0 (0.39)	Rutter	3.9 (0.55)
23	1986	Steinhausen	Germany	279 616	Urban	0–15	S	L	R	Rutter	1.9 (0.26)	–	–
24	1986	Steffenburg	Sweden	42 886	Mixed	0–9	P	L	P	DSM-III	4.7 (1.05)	DSM-III	6.9 (1.27)
25	1987	Burd	USA	180 986	Mixed	2–18	C	L	P	DSM-III	1.2 (0.26)	DSM-III	3.3 (0.43)
26	1987	Matsuishi	Japan	32 834	Urban	4–12	P	R	P	DSM-III	15.5 (2.17)	–	–
27	1988	Tanoue	Japan	95 394	Rural	7	P	C	P	DSM-III	13.8 (1.20)	–	–
28	1988	Bryson	Canada	20 800	Mixed	6–14	P	Q	P	DSM-III	1.9 (0.96)	Denkla Triad	10.1 (2.2)
29	1989	Ritvo	USA	526 514	Mixed	3–17	P	L	P	DSM-III	2.92 (0.24)	–	–
30	1989	Sugiyama	Japan	11 320	Urban	1.5	P	C	P	DSM-III	13.0 (3.37)	–	–
31	1989	Cialdella	France	135 180	Urban	5–9	C	L	R	DSM-III	5.1 (0.61)	DSM-III	10.8 (0.89)
32	1991	Gillberg	Sweden	78 102	Mixed	4–13	C	L	P	DSM-III-R	7.0 (0.95)	DSM-III-R	9.4 (1.1)
33	1992	Ohtaki	Japan	35 366	Mixed	6–14	S	R	P	DSM-III-R	13.9 (1.98)	–	–
34	1992	Fombonne	France	274 816	Mixed	9 & 13	C	R	R	ICD-9	4.9 (0.42)	–	–
35	1993	Herder	Norway	50 909*	–	1–17	C	–	–	DSM-III-R	5.5 (1.04)	–	–
36	1996	Honda	Japan	8 537	Urban	5	P	C	P	ICD-10	21.1 (4.97)	–	–
37	1997	Arvidsson	Sweden	1 941	Mixed	3–6	P	C	P	ICD-10	31 (12.6)	ICD-10	46 (15.36)
38	1997	Webb	UK	73 300	Mixed	3–15	P	L	P	DSM-III-R	7.2 (0.98)	–	–
39	1997	Fombonne	France	325 347	Mixed	6–16	C	R	R	ICD-10	5.35 (0.41)	ICD-10	16.29 (0.71)
40	1998	Sponheim	Norway	65 688	Mixed	3–14	P	L	P	ICD-10	3.8 (0.76)	ICD-10	5.2 (0.89)
41	1999	Kadesjo	Sweden	826	Urban	6–7	P	L	P	ICD-10	60 (26.87)	Gillberg’s criteria	121 (38.04)
42	2000	Powell	UK	16 049*	Mixed	0 to <5	S	R	R	DSM-III-R or ICD-10**	16.2 (3.17)	ICD-10	33.7 (1.48)
43	2000	Kielinen	Finland	152 732	Mixed	3–18	C	R	R	ICD-10	5.6 (0.61)	ICD-10	13.9 (0.95)
44	2000	Baird	UK	16 235	Urban	1.5†	P	Q (CHAT)	P	ICD-10	30.8 (4.35)	ICD-10	57.9 (5.95)
45	2001	Magnusson	Iceland	43 153	Mixed	5–14‡	P	C	R	ICD-10	8.6 (1.41)	ICD-10	13.2 (1.75)
46	2001	Bertrand	USA	8 896	Urban	3–10	P	R	P (where possible)	DSM-IV	40.0 (6.69)	DSM-IV	67 (8.65)
47	2001	Chakrabarti	UK	15 500	Mixed	2.5–6.5	P	C	P	DSM-IV	16.8 (3.29)	DSM-IV	62.6 (6.34)
48	2002	Croen	USA	4 590 333	Mixed	0–12	S	R	R	DSM-III & DSM-IV††	11.0 (0.15)	–	–
49	2003	Lingam	UK	186 206	Mixed	5–14	S	R	R	ICD-10	14.9 (0.89)	ICD-10	30.4 (1.28)
50	2004	Tebruegge	UK	2 536	Mixed	8–9	P	R	R	ICD-10	23.7 (9.7)	ICD-10	82.8 (18.0)
ASD papers
51	2001	Fombonne	UK	10 438	Mixed	5–15	P	Q (DAWBA)	P	–	–	DSM-IV and ICD-10 (excl Rett’s)	26.1 (5.0)
52	2002	Scott	UK	43 472	Mixed	5–11	P	L	R	–	–	ICD-10	57.0 (3.61)
53	2003	Yeargin-Allsopp	USA	289 456	Urban	3–10	C	R	R	–	–	DSM-IV	34 (1.08)