TABLE 3—
Means and Standard Deviations of Symptom Rating by Cluster
| Cluster (Mean [Standard Deviation]) | ||||
| Symptom | 1 | 2 | Mean Difference | T valuea |
| Unexplained weakness | .60 (.79) | 2.12 (.88) | 1.52 | 28.12 |
| Pain in arms or legs | .73 (.90) | 2.23 (.83) | 1.50 | 26.28 |
| Prolonged fatigue after mild exercise | .58 (.84) | 2.08 (.94) | 1.50 | 26.14 |
| Pain in more than 1 joint | .88 (.94) | 2.29 (.84) | 1.42 | 24.01 |
| Sudden mood changes | .95 (.98) | 2.36 (.91) | 1.41 | 22.71 |
| Muscle aches or cramps | .73 (.83) | 2.14 (.78) | 1.41 | 26.54 |
| Feeling anxious or upset | .81 (.91) | 2.20 (.93) | 1.40 | 23.29 |
| Fatigue not due to exercise | 1.13 (.93) | 2.48 (.69) | 1.34 | 24.29 |
| Feeling sickly | .47 (.72) | 1.80 (.92) | 1.33 | 25.37 |
| Pain in arms, hands, or shoulders | .67 (.89) | 1.99 (1.02) | 1.32 | 21.36 |
| Feeling depressed or blue | .80 (.91) | 2.10 (.97) | 1.30 | 21.23 |
| Numbness or tingling sensations | .60 (.81) | 1.86 (.94) | 1.26 | 22.45 |
| Sensitivity to heat or cold | .49 (.85) | 1.74 (1.15) | 1.25 | 19.46 |
| Unrefreshing sleep (waking up tired) | 1.32 (1.00) | 2.55 (.69) | 1.23 | 21.12 |
| Abdominal pain | .39 (.71) | 1.63 (.99) | 1.23 | 22.59 |
| Difficulty concentrating | .87 (.91) | 2.09 (.87) | 1.22 | 20.81 |
| Stomach or digestive system problems | .63 (.90) | 1.85 (.98) | 1.22 | 19.89 |
| Back problems | .80 (.95) | 1.98 (.99) | 1.18 | 18.59 |
| Abdominal gas | .68 (.87) | 1.85 (.97) | 1.17 | 19.62 |
| Difficulty remembering | 1.08 (.94) | 2.25 (.81) | 1.17 | 20.04 |
| Chest discomfort or pain | .56 (.78) | 1.72 (.91) | 1.17 | 21.42 |
| Difficulty breathing | .51 (.78) | 1.62 (.93) | 1.11 | 20.14 |
| Losing balance or feeling dizzy | .47 (.70) | 1.55 (.94) | 1.08 | 20.49 |
| Extra sensitivity to chemicals | .57 (.89) | 1.64 (1.11) | 1.07 | 16.66 |
| Headaches | 1.06 (1.05) | 2.12 (.88) | 1.06 | 16.50 |
| Nausea | .26 (.56) | 1.30 (.96) | 1.04 | 21.39 |
| Fever or chills | .22 (.56) | 1.25 (1.06) | 1.02 | 19.78 |
| Coughing | .52 (.76) | 1.53 (.98) | 1.02 | 18.32 |
| Sleeping more than usual | .65 (.91) | 1.64 (1.23) | .99 | 14.48 |
| Diarrhea | .55 (.84) | 1.50 (1.05) | .95 | 15.68 |
| Sweating (not due to exercise) | .47 (.86) | 1.42 (1.12) | .95 | 14.95 |
| Mouth, teeth, or gum problems | .52 (.83) | 1.44 (1.11) | .93 | 14.85 |
| Nose or sinus problems | 1.07 (1.06) | 2.00 (1.02) | .93 | 13.62 |
| Skin problems (including rashes) | .92 (1.03) | 1.82 (1.05) | .90 | 13.21 |
| Ear or hearing problems | .61 (.83) | 1.47 (1.01) | .86 | 14.57 |
| Throat problems | .29 (.63) | 1.14 (1.00) | .85 | 16.22 |
| Eye or vision problems | .66 (.83) | 1.48 (.96) | .82 | 14.22 |
| Swollen glands | .29 (.61) | 1.08 (1.05) | .80 | 14.87 |
| Cuts or sores that heal slowly | .38 (.71) | 1.17 (1.12) | .79 | 13.56 |
| Sexual or genital problems | .34 (.72) | 1.09 (1.15) | .76 | 12.64 |
| Difficulty swallowing | .17 (.49) | .87 (.94) | .70 | 15.32 |
| Hair problems | .28 (.70) | .95 (1.09) | .67 | 11.71 |
| Reduced ability to taste | .13 (.41) | .78 (.94) | .65 | 14.73 |
| Irregular heartbeat | .25 (.60) | .87 (1.04) | .63 | 11.95 |
| Constipation | .22 (.54) | .83 (1.01) | .61 | 12.34 |
| Frequent or painful urination | .24 (.59) | .85 (.99) | .61 | 12.02 |
| Vomiting | .09 (.38) | .69 (.91) | .61 | 14.39 |
| Fainting spells | .05 (.25) | .42 (.81) | .38 | 10.68 |
Note. Factor values are on a scale of 0 (not present), 1 (mild), 2 (moderate), and 3 (severe).
aAll T values significant at P < .0001.