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Table 1 Characteristics of studies on the prevalence of CFS/ME (± SD)

From: Systematic review and meta-analysis of the prevalence of chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME)

Group Community Primary care Total
Number of articles included (%) 30 (67) 15 (33) 45 (100)
Number of studies includeda(%) 30 (65) 16 (35) 46 (100)
Prospective 25 (54) 16 (35) 41 (89)
Retrospective 4 (9) 1 (2) 5 (11)
Number of prevalence datab (%) 33 (59) 23 (41) 56 (100)
Total number of participants 540,901 545,075 1085,976
Mean N. of participants 18,030 ± 38,094 34,067 ± 61,325 23,608 ± 48,092
Total number of known sexc 120,765 10,077 130,842
 Male 58,752 3318 62,070
 Female 62,013 6759 68,772
 M:F ratio 48:52 25:75 45:55
Mean age of participantsd 41.1 ± 11.3 38.0 ± 6.5 40.0 ± 9.9
 Male 41.1 ± 11.3 38.0 ± 6.8 39.9 ± 10.0
 Female 41.2 ± 11.4 38.1 ± 6.1 40.0 ± 9.8
N. of (studies)/prevalence data by subgroup (N. of participants)
 Publication year
  1990–2000 8 (177,201) 15 (318,391) (18)/23 (495,592)
  2001–2010 19 (86,512) 4 (9895) (20)/23 (96,407)
  2011–2018 6 (277,188) 4 (216,789) (8)/10 (493,977)
 Population group
  General population (≥ 18 years) 24 (489,961) 20 (466,565) (34)/44 (956,526)
  Children/adolescents (< 18 years) 6 (43,671) 1 (73,636) (7)/7 (117,307)
  Specific populatione 3 (7269) 2 (4874) (5)/5 (12,143)
 Case definition (8 case definitions) 23 (339,192) 11 (298,739) 34 (637,931)
  CDC-1994 [22] 4 (20,037) 4 (27,454) 8 (47,491)
  Holmes [23] 2 (116,520) 2 (2980) 4 (119,500)
  Australian [25] 2 (3215) 2 (2980) 4 (6195)
  Oxford [24] 1 (10,396) 3 (505,299) 4 (515,695)
  CCC [27] ECD [26] PVES [28] NICE [29] f N/Ag 1 (59,101) 1 (1874) 2 (60,975)
 Country (13 countries)   
  Western 27 (516,617) 17 (473,009) (34)/44 (989,626)
  Asian 5 (23,197) 5 (70,192) (10)/10 (93,389)
  Othersh 1 (1087) 1 (1874) (2)/2 (2961)
 Diagnostic method   
  Interview (medical test −) 19 (111,943) 3 (68,848) (19)/22 (180,791)
  Interview (medical test +) 9 (57,339) 14 (17,445) (18)/23 (74,784)
  Physician diagnosis 1 (114,000) 5 (435,782) (4)/6 (549,782)
  Medical records 4 (257,619) 1 (23,000) (5)/5 (280,619)
  1. aThe number of studies is larger (n = 46) than the number of article as one article included two studies
  2. bSome articles included multiple applications of case definitions; thus, the number is larger than the total number of studies
  3. cTwenty-one studies (24 prevalence data points) included information about participant sex
  4. dThe mean age of the participants whose sex was known (12 studies) was estimated using either the reported mean age for each sex or the mean age for both. Children and adolescents were excluded
  5. eSpecific groups included nurses, Gulf War veterans, livestock workers, company employees, etc
  6. fCCC, Canadian Consensus Criteria; ECD, epidemiological case definition; PVES, post viral exhaustion syndrome; and NICE, National Institute for Health and Care Excellence guideline 2007
  7. gTwo N/A cases had no verification of case definition or defined criteria
  8. hOther countries included India and Nigeria