We also performed subgroup meta - analyses by type of prevention (primary v secondary: in this study, trials involving healthy populations or patients with any specific disease except for cardiovascular disease were classified
as primary prevention trials, and trials involving patients with cardiovascular disease were classified
as secondary prevention trials), type of supplement by quality and dose (each supplement, vitamins only, antioxidants only, or antioxidants excluding vitamins), type of outcome (cardiovascular death, angina, fatal or non-fatal myocardial infarction, stroke, or transient ischaemic attack), type of outcome in each supplement, type of study design (randomised, double blind,
placebo controlled trial v open
label, randomised controlled trial), methodological quality (high v low), duration of treatment (< 5 years v ≥ 5 years), funding source (pharmaceutical industry v independent organisation), provider of supplements (pharmaceutical industry v not pharmaceutical industry), type of control (
placebo v no
placebo), number of participants (≥ 10000 v < 10000), and supplements given singly or in combination with other vitamin or antioxidant supplements by quality.
In another example of
placebos and meds interacting in curious ways, one study found that when patients took a migraine drug that was
labeled «
placebo,» it worked half
as well
as it did for patients who took the same drug, properly
labeled.
Antidepressants such
as Prozac and Celexa have been shown to be better than
placebo at treating hot flashes, and doctors sometimes prescribe these and other antidepressants for hot flashes «off -
label» (i.e., without the FDA's official OK).