Table 1.

Symptoms Included in Case Definition Algorithms

Symptom	Fukuda	Canadian	IOM
Fatigue	X	X	X
Minimum exercise makes you physically tired	X	X	X
Next-day soreness/fatigue after everyday activities	X	X	X
Physically drained or sick after mild activity	X	X	X
Dead, heavy feeling after starting to exercise	X	X	X
Mentally tired after the slightest effort	X	X	X
Unrefreshed after you wake up in the morning	X	X	X
Problems staying asleep		X	X
Problems falling asleep		X	X
Need to nap daily		X	X
Waking up early in the morning (e.g. 3am)		X
Sleeping all day and staying awake all night		X	X
Pain or aching in your muscles	X	X
Pain/stiffness/tenderness in >1 joint	X	X
Headaches	X	X
Bloating		X
Abdomen/Stomach pain		X
Eye pain		X
Chest pain		X
Difficulty paying attention for a long period of time	X	X	X
Problems remembering things	X	X	X
Only able to focus on one thing at a time		X	X
Difficulty expressing thoughts	X	X	X
Muscle weakness		X
Absent-mindedness or forgetfulness	X	X	X
Sensitivity to noise		X
Slowness of thought	X	X	X
Sensitivity to bright lights		X
Difficulty understanding things	X	X	X
Unable to focus vision and/or attention		X
Muscle twitches		X
Loss of depth perception		X
Irritable bowel problems		X
Feeling unsteady on your feet, like you might fall		X	X
Shortness of breath or trouble catching your breath		X	X
Dizziness or fainting		X	X
Bladder problems		X
Nausea		X
Irregular heart beats		X	X
Cold limbs		X
Feeling hot or cold for no reason		X
Losing or gaining weight without trying		X
Chills or shivers		X
Night sweats		X
Alcohol intolerance		X
Feeling like you have a high temperature		X
Feeling like you have a low temperature		X
No appetite		X
Sweating hands		X
Flu-like symptoms		X
Some smells/foods/meds/chemicals make you feel sick		X
Tender/Sore lymph nodes	X	X
Sore throat	X	X
Fever		X

X: Indicates that items are included in the original, full-form DSQ case definition algorithms

Shaded boxes: Indicate that the item is included in the DSQ-SF case definition algorithms