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Evidence found and GRADE certainty

4,756 questions · 13,493 findings · 1,305 reviews · Headline outcomes only

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No studies found 2,594 · 19.2%GRADE not reported 728 · 5.4%Very low 2,868 · 21.3%Low 3,777 · 28%Moderate 2,620 · 19.4%High 906 · 6.7%

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Levetiracetam vs placebo

Adverse effects: headache · people with drug‐resistant focal epilepsy

Levetiracetam showed no clear difference in adverse effects: 5 most common adverse effects (any age) – headache compared with placebo (low certainty).

1 finding from 1 review

Levetiracetam vs placebo

Adverse effects: 5 most common adverse effects (any age) – dizziness · people with drug‐resistant focal epilepsy

Levetiracetam showed no clear difference in adverse effects: 5 most common adverse effects (any age) – dizziness compared with placebo (moderate certainty).

1 finding from 1 review

Levetiracetam vs placebo

Adverse effect: fatigue · people with drug‐resistant focal epilepsy

Levetiracetam showed no clear difference in adverse effects: 5 most common adverse effects (any age) – fatigue… compared with placebo (moderate certainty).

1 finding from 1 review

Levetiracetam vs placebo

Adverse effects: 5 most common adverse effects (any age) – accidental injury · people with drug‐resistant focal epilepsy

Levetiracetam showed no clear difference in adverse effects: 5 most common adverse effects (any age) –… compared with placebo (low certainty).

1 finding from 1 review

Vitamin A vs placebo

Incidence: lung cancer · healthy people and healthy male physicians

Vitamin A showed no clear difference in incidence: lung cancer compared with placebo (high certainty).

1 finding from 1 review

Vitamin C vs placebo

Incidence: lung cancer ‐ women · healthy male physicians, period: 1997 to 2007 and female health professionals, period: 1998 to 2005

Vitamin C leads to higher incidence: lung cancer ‐ women compared with placebo (high certainty).

1 finding from 1 review

Vitamin C vs placebo

Mortality: lung cancer ‐ men · healthy male physicians, period: 1997 to 2007 and female health professionals, period: 1998 to 2005

Vitamin C showed no clear difference in mortality: lung cancer ‐ men compared with placebo (high certainty).

1 finding from 1 review

Vitamin C vs placebo

Incidence: all cancers · healthy male physicians, period: 1997 to 2007 and female health professionals, period: 1998 to 2005

Vitamin C showed no clear difference in incidence: all cancers compared with placebo (high certainty).

1 finding from 1 review

Vitamin C vs placebo

Mortality: all cancers · healthy male physicians, period: 1997 to 2007 and female health professionals, period: 1998 to 2005

Vitamin C showed no clear difference in mortality: all cancers compared with placebo (high certainty).

1 finding from 1 review

Vitamin D plus calcium vs placebo

Adverse events: serum calcium above normal · relatively healthy postmenopausal women

Vitamin D plus calcium showed no clear difference in adverse events: serum calcium above normal compared with placebo (low certainty).

1 finding from 1 review

Vitamin A vs placebo

Mortality: lung cancer · healthy people and healthy male physicians

Vitamin A showed no clear difference in mortality: lung cancer compared with placebo (high certainty).

1 finding from 1 review