Table 1.

Severity (mean ± SD) of 48 symptoms at time 1 and time 2 for highly symptomatic and mildly symptomatic clusters and overall means.

	Mild		High
Symptom	Time 1 (n = 242)	Time 2 (n = 242)	Time 1 (n = 148)	Time 2 (n = 148)	Overall mean Time 1/time 2
Headaches	0.85 ± 0.98	0.85 ± 0.97	2.11 ± 0.91	1.77 ± 0.98*	1.33/1.20
Eyes or vision	0.51 ± 0.79	0.67 ± 0.83	1.36 ± 0.94	1.45 ± 0.94	0.83/0.96
Ears or hearing	0.55 ± 0.83	0.69 ± 0.89	1.37 ± 1.05	1.30 ± 1.01	0.86/0.93
Nose or sinuses	0.86 ± 1.02	0.94 ± 1.01	1.86 ± 1.07	1.74 ± 1.11	1.24/1.25
Multiple chemical sensitivities	0.39 ± 0.74	0.51 ± 0.86	1.51 ± 1.12	1.57 ± 1.17	0.81/0.92
Mouth, teeth, and gums	0.41 ± 0.75	0.50 ± 0.83	1.25 ± 1.11	1.22 ± 1.08	0.73/0.77
Ability to taste	0.06 ± 0.26	0.12 ± 0.39	0.69 ± 0.90	0.70 ± 0.89	0.30/0.34
Difficulty swallowing	0.11 ± 0.41	0.21 ± 0.56	0.72 ± 0.85	0.73 ± 0.93	0.34/0.41
Throat problems	0.22 ± 0.55	0.26 ± 0.64	1.03 ± 1.04	0.84 ± 0.94	0.53/0.48
Swollen glands	0.18 ± 0.46	0.25 ± 0.58	1.01 ± 1.05	0.79 ± 0.94	0.49/0.46
Difficulty breathing	0.33 ± 0.66	0.36 ± 0.69	1.45 ± 1.00	1.03 ± 0.95*	0.75/0.62
Coughing	0.38 ± 0.65	0.46 ± 0.74	1.39 ± 1.07	1.21 ± 1.06	0.76/0.74
Chest discomfort	0.43 ± 0.74	0.48 ± 0.75	1.56 ± 0.94	1.33 ± 1.01	0.86/0.80
Irregular heartbeat	0.16 ± 0.52	0.29 ± 0.62	0.71 ± 1.03	0.71 ± 0.91	0.37/0.45
Arms, hands, and shoulders	0.55 ± 0.87	0.67 ± 0.87	1.82 ± 1.08	1.63 ± 1.03	1.03/1.03
Back problems	0.70 ± 0.90	0.86 ± 0.98	1.78 ± 1.01	1.75 ± 1.11	1.11/1.20
Nausea	0.18 ± 0.45	0.21 ± 0.56	0.99 ± 0.95	0.84 ± 0.93	0.49/0.45
Vomiting	0.05 ± 0.25	0.09 ± 0.40	0.47 ± 0.77	0.39 ± 0.73	0.21/0.20
Stomach or digestive problems	0.52 ± 0.86	0.69 ± 0.93	1.59 ± 1.07	1.53 ± 1.08	0.93/1.01
Diarrhea	0.39 ± 0.73	0.48 ± 0.80	1.29 ± 1.08	1.21 ± 1.08	0.73/0.76
Constipation	0.17 ± 0.51	0.24 ± 0.57	0.61 ± 0.85	0.74 ± 0.95	0.33/0.43
Abdominal gas	0.54 ± 0.81	0.72 ± 0.95*	1.74 ± 1.05	1.54 ± 1.10	0.99/1.03
Abdominal pain	0.29 ± 0.66	0.42 ± 0.74	1.41 ± 0.98	1.26 ± 1.04	0.72/0.74
Frequent or painful urination	0.16 ± 0.46	0.24 ± 0.66	0.74 ± 0.95	0.69 ± 0.90	0.38/0.41
Muscle aches or cramps	0.57 ± 0.81	0.82 ± 0.93*	1.95 ± 0.86	1.81 ± 1.06	1.09/1.19
Sexual or genital problems	0.21 ± 0.52	0.28 ± 0.67	0.97 ± 1.12	0.93 ± 1.10	0.50/0.53
Numbness or tingling	0.47 ± 0.73	0.70 ± 0.86*	1.80 ± 0.89	1.72 ± 1.08	0.97/1.08
Pain in arms and legs	0.57 ± 0.82	0.79 ± 0.95*	2.11 ± 0.87	1.88 ± 1.06	1.15/1.20
Pain in more than one joint	0.71 ± 0.92	0.86 ± 0.99	2.17 ± 0.88	2.05 ± 1.00	1.27/1.31
Skin (including rashes)	0.74 ± 0.95	0.68 ± 0.98	1.69 ± 1.12	1.37 ± 1.15	1.10/0.94
Hair problems	0.18 ± 0.51	0.21 ± 0.61	0.81 ± 1.03	0.72 ± 1.00	0.42/0.40
Cuts or sores	0.34 ± 0.66	0.33 ± 0.70	1.04 ± 1.06	0.91 ± 1.06	0.61/0.55
Fainting spells	0.05 ± 0.26	0.06 ± 0.29	0.32 ± 0.73	0.24 ± 0.56	0.15/0.13
Losing balance/dizziness	0.38 ± 0.64	0.52 ± 0.77	1.43 ± 1.04	1.27 ± 0.93	0.78/0.80
Difficulty concentrating	0.62 ± 0.81	0.81 ± 0.89*	1.99 ± 0.90	1.87 ± 0.91	1.14/1.21
Difficulty remembering	0.81 ± 0.90	1.04 ± 0.94	2.13 ± 0.88	2.11 ± 0.94	1.31/1.45
Feeling sickly	0.31 ± 0.59	0.42 ± 0.74	1.59 ± 0.98	1.37 ± 0.99	0.80/0.78
Unrefreshing sleep	1.01 ± 0.95	1.14 ± 0.97	2.48 ± 0.73	2.26 ± 0.83*	1.57/1.57
Sleeping more than usual	0.54 ± 0.82	0.54 ± 0.86	1.62 ± 1.21	1.28 ± 1.20*	0.95/0.82
Fatigue (not from exercise)	0.92 ± 0.87	1.04 ± 0.98	2.34 ± 0.81	2.18 ± 0.81	1.46/1.47
Fatigue after exercise	0.37 ± 0.71	0.55 ± 0.86	1.82 ± 1.06	1.74 ± 1.13	0.92/1.00
Unexplained weakness	0.39 ± 0.64	0.48 ± 0.79	1.91 ± 0.98	1.72 ± 1.04	0.96/0.95
Feeling anxious	0.61 ± 0.76	0.71 ± 0.91	2.00 ± 0.95	1.74 ± 1.01	1.14/1.10
Sudden mood changes	0.64 ± 0.81	0.72 ± 0.90	2.11 ± 1.02	1.80 ± 1.07*	1.20/1.13
Sensitivity to heat or cold	0.37 ± 0.71	0.44 ± 0.80	1.49 ± 1.18	1.34 ± 1.18	0.79/0.78
Fever or chills	0.14 ± 0.42	0.19 ± 0.52	1.09 ± 1.05	0.84 ± 0.92	0.50/0.44
Sweating	0.31 ± 0.73	0.48 ± 0.84	1.39 ± 1.10	1.28 ± 1.11	0.72/0.79
Feeling depressed or blue	0.59 ± 0.80	0.71 ± 0.98	1.95 ± 1.00	1.61 ± 1.09*	1.11/1.05

^*Significantly different from time 1 to time 2 within highly symptomatic and mildly symptomatic clusters.