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Table 1
Characteristics of included studies
Study	Country	Number of people with CFS/ME*	CFS/ME illness		Age (years)	Female gender	Ethnicity and Socioeconomic status

			Duration (years)	Severity

Anonymous 1997[13]	United States	1	NR	Moderate to severe	Adult	100%	NR

Asbring 2002[24]; Asbring 2004[21]	Sweden	12	1 to 23	A range: full time employed to sick leave, temporary disability or sickness pensions.	32 to 65	100%	NR

Ashby et al 2006[27]	United Kingdom	10	0.4 to 2	NR	8 to 16	70%	NR

Blake 1993[14]	Canada	1	NR	Severe	29	100%	Caucasian, well educated

Carlsen 2003[22]	Norway	5	NR	NR	23 to 67	80%	NR

Clarke 1999[6]; Clarke & James 2003[7]	Canada	59	A range	80% Severe; 20% moderate	18 to 80	65%	Ethnicity NR; a range of education levels

Denz-Penhey 1993[18]	New Zealand	10	NR	NR	6 to 18	NR	NR

Dumit, 2006[5]	United States	NR (180,000 on-line discussion postings)	NR	NR	NR	NR	NR

Edwards et al 2007[8]	United Kingdom	8	<1	Moderate to severe	18 +	100%	White British, Chinese and mixed; Socioeconomic NR

Garralda & Rangel 2004[10]	United Kingdom	28	NR	Moderate to severe, but all at school or home tuition	10 to 18	78%	A range of ethnicity and social class

Gray & Fossey 2003[35]	Australia	5	2 to 10	Severe	16 to 44	NR	NR

Green et al 1999[11]	United States	44	Mean 4.1	NR	18 to 57	89%	A range of ethnicity; socioeconomic NR

Hammond 2002[34]	United Kingdom	586	NR	NR	NR	NR	NR

Hoad 1994[15]	United Kingdom	1	3	Moderate	fifties	100%	White British; Socioeconomic NR

Horton-Salway 2004[28]	United Kingdom	15	NR	NR	NR	NR	NR

Jackson 1994[31]	United Kingdom	3	2 to 6	Severe	20 to 51	100%	NR

Jason et al 1996[40]	United States, Canada, Mexico	984	NR	A range	18 to 84	99%	NR

Lee et al 2001[30]	Canada	50	NR	Severe	20 to 64	56%	NR

Moore 2001[37]	United States	1	8	Moderate	NR	100%	Ethnicity NR; High education

Ong et al 2005[19]	United Kingdom	1	17	Severe	NR	100%	NR

Prins et al 2004[32]	The Netherlands	268	2 and more	NR	18 to 60	78.5%	NR

Rangel et al 2000[41]	United Kingdom	25	More than 3	Severe	12 to 20	NR	NR

Reynolds and Vivat 2006[26]	United Kingdom	3	16 and more	Moderate to severe	51 to 62	100%	White British; high education and 'home-maker'

Richards et al 2006[33]	United Kingdom	21	More than 3	Moderate to severe	11 to 20	62%	NR

Roche & Tucker 2003[23]	United Kingdom	≈ 474	A range	NR	12 to 20	NR	NR

Schoofs et al 2004[29]	United States	46	NR	NR	18 and more	91%	NR

Schweitzer et al 1995[36]	Australia	47	NR	Moderate to severe	26 to 50	70%	NR

Sutton 1996[17]	United Kingdom	2	15 to 30	Moderate to severe	NR	50%	NR

Taylor & Kielhofner 2003[12]	United States	1	3	Moderate	28	100%	2^ndgeneration Irish immigrants; High education

Taylor 2004[9]	United States	47	NR	Moderate to severe	mean 49	96%	A range of ethnicity and social class

Weisstein, 2006[16]	United States	1	26	Extremely Severe	About 50	100%	Non- minority; High education

Whitehead 2006a[25]; 2006b[20]	United Kingdom	17	A range	Severe	13 to 63	65%	NR

NR: not reported
Drachler et al. BMC Public Health 2009 9:458 doi:10.1186/1471-2458-9-458

Table 1