Table 5.
Prevalence of Institute of Medicine ME/CFS criteria.
| ME/CFS (n = 55)(%) | HC (n = 55)(%) | P | |
|---|---|---|---|
| 1. Substantially impaired function | |||
| Fatigue (several times/week or | |||
| more) | 100 | 5 | <0.001 |
| FDI or PedsQL >2 SD worse | |||
| than mean scores for HC* | 96 | 7 | |
| 2. Unrefreshing sleep (most/all of | |||
| the time) | 98 | 18 | <0.001 |
| 3. Post-exertional malaise (at | |||
| least once in 2 weeks) | 95 | 7 | <0.001 |
| 4.a. Cognitive impairment | |||
| Trouble thinking and | |||
| concentrating (several | |||
| times/week or more) | 82 | 2 | <0.001 |
| Symptom frequency plus | |||
| WMFI or | |||
| MFS cognitive subscale >2 | |||
| SD worse than mean for HC* | 93 | 11 | |
| 4.b. Orthostatic intolerance | |||
| LH (several times/week or | |||
| more) | 76 | 15 | <0.001 |
| LH frequency plus pre-study | |||
| diagnosis/treatment of OI | 84 | 15 | <0.001 |
*
P-values not computed because of the >2SD method of operationalizing the criterion.
HC, healthy controls; FDI, Functional Disability Inventory; PedsQL, Pediatric Quality of Life Inventory; WMFI, Wood Mental Fatigue Inventory; MFS, PedsQL Multidimensional Fatigue Scale; LH, lightheadedness; OI, orthostatic intolerance.