Table 3.
Clinical characteristics of CFS subjects at initial classification (N = 65)
| Characteristic | Description |
| Age at onset (mean, standard deviation, range) in years | 37.1 (11.0, 5–57) |
| Median proportion of life with illness* | 13.0 |
| Self reported onset type (%) | |
| Gradual | 76.9 |
| Sudden | 20.0 |
| Don't know/declined reply | 3.1 |
| Body mass index (%) | |
| 20–24: Normal | 26.2 |
| 25–29: Overweight | 33.8 |
| ≥ 30:Obese | 40.0 |
| Median (interquartile range) | 27 (24–31) |
| Ever been diagnosed or treated by a physician (%) | |
| Fibrositis or fibromyalgia | 32.3 |
| Depression | 30.8 |
| Allergies confirmed by formal testing | 21.5 |
| Irritable bowel syndrome | 18.5 |
| Temporomandibular joint syndrome | 16.9 |
| CFS | 13.9 |
| Environmental sensitivity disease | 1.5 |
| Yeast infection (only females) | 48.2 |
| Diagnostic Interview Schedule (%) | |
| Current/Lifetime somatization | 0 |
| Lifetime major depression disorder | 16.9 |
* Ratio between illness duration (in years) and age (in years)