for the main comparison.

Amitriptyline compared with placebo for fibromyalgia
Patient or population: adults with fibromyalgia Settings: community Intervention: amitriptyline 25 to 50 mg daily Comparison: placebo
Outcomes	Probable outcome with intervention	Probable outcome with placebo	NNT or NNH and/or relative effect (95% CI)	No of Participants (studies)	Quality of the evidence (GRADE)	Comments
At least 50% reduction in pain or equivalent (substantial)	360 in 1000	110 in 1000	RR 2.9 (1.7 to 4.9) NNT 4.1 (2.9 to 6.7)	4 studies, 275 participants	Very low	Small number of studies and participants
At least 30% reduction in pain or equivalent (moderate)	no data
Adverse event withdrawals	80 in 1000	90 in 1000	RR 1.03 (0.49 to 2.2) NNTp not calculated	4 studies, 298 participants	Very low	Small number of studies and participants
Serious adverse events	none reported
Death	none reported
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.