Table 6

Proportion of reported symptoms in prevalent cases, according to study case definitionsa

Current symptoms

All cases

(n = 265)

CDC-1994

(n = 258)

Canadian

(n = 142)

ECD

(n = 43)


Sleep dysfunction

Unrefreshing sleep

97.4

97.3

100.0

97.7

Sleep problems

84.9

85.3

94.4

73.0


Neurological/Cognitive manifestations

Memory/concentration problems

94.3

95.3

98.0

95.3

Difficulty thinking

81.5

82.0

93.0

74.4

Unexplained muscle weakness

75.1

74.8

88.0

70.0

Light/noise sensitivity

65.7

66.0

82.4

65.1

Difficulty in understanding things

58.1

59.3

76.1

48.8

Confusion or disorientation

54.7

55.0

78.2

44.2


Pain

Pain in two or more joints

89.8

91.1

94.4

76.7

Muscle pain

88.9

89.5

95.1

74.4

Muscle discomfort

86.8

88.0

94.4

76.7

Migratory joint pain

75.8

76.4

85.2

53.5

Headaches

64.5

65.5

74.6

60.5

Migraine

28.3

28.3

36.6

25.6


Fatigue/tiredness

Fatigue after exercise (> 24 hours)

81.1

80.6

100.0

90.7

Intolerance to exercise

71.7

71.7

85.2

81.4

Malaise after exertion (> 24 hours)

69.1

69.4

85.9

86.0


Psychological

Anxiety

70.9

72.5

83.1

39.5

Depression

55.8

56.2

67.6

11.6


Autonomic

Sweatiness/cold hands and feet

66.4

67.4

88.0

55.8

Intolerance to be on your feet

61.1

60.8

79.6

55.8


Immunological

Sore throat

57.0

56.7

71.8

60.5

Tender glands in the neck/armpits

57.0

57.7

74.6

55.8

Mild fever or chills

52.8

52.7

75.3

46.5


aAll cases complying with each of the definitions are shown in the columns; therefore cases meeting more than one diagnostic criterion appear more than once.

Nacul et al. BMC Medicine 2011 9:91   doi:10.1186/1741-7015-9-91

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