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87 lines
2.9 KiB
Plaintext
87 lines
2.9 KiB
Plaintext
8 months ago
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help for ^metannt^
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Estimates of absolute benefit or risk from meta-analysis
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--------------------------------------------------------
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^metannt , measure(^or|rr|rd^) size(^#^) confint(^#,#^) baseline(^#[,#...#]^)^
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Description
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-----------
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This program is intended to aid interpretation of meta-analyses of binary
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data by presenting the effect sizes in absolute terms. Both the number
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needed to treat (NNT) and the number of events avoided (or added) per
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1000 are presented.
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The ^Number Needed to Treat (NNT)^ is the number of individuals required
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to experience the intervention in order to expect there to be one
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additional event to be observed. Assuming the event is undesireable, this
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is termed the "number needed to treat to benefit" (NNTB). If the
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intervention arm experiences more events, this is commonly refered to as
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the "number needed to treat to harm" (NNTH).
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^metannt^ calculates this by deriving an effect size (e.g. a risk ratio),
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applying it to a population with a given event prevalance, and from this
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deriving a projected event rate if the population were to receive the
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intervention. The NNT is equal to
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1/(control group event rate - treatment group event rate).
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The ^number of avoided or excess events (respectively) per 1000 population^
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is the difference between the two event rates multiplied by 1000. The
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intervention group event rate is calculated in the same manner as with
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the NNT. Optionally a confidence interval is also presented, using the
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confidence limits of the effect size applied to the control group event
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rate.
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Options for ^metannt^
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-------------------
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^baseline()^ specifies the baseline (ie. control group) event rates, from
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which the NNT and number of events avoided are computed from. More than
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one baseline event rate may be specified.
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^measure(^rr|or|rd^)^ specifies whether the estimated effect size pooled is
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a risk ratio, odds ratio or (absolute) risk difference.
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^size(^#^)^ denotes the size of the effect
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^confint(^#,#^)^ denotes the confidence interval around the effect size.
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By default the saved results from the r() macros within @metan@ are used to
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derive the control group event rate, the effect measure, the effect size and
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its confidence interval. However, unless a recent version of metan (1.71
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onwards) was used immediately beforehand, the first three options must be
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specified. The confidence interval is optional.
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Examples
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--------
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. ^metannt , measure(rr) size(0.2) baseline(0.1,0.2,0.3)^
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. ^metan tdeath tnodeath cdeath cnodeath, or^
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. ^metannt , baseline(0.15)^
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Authors
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-------
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Michael J Bradburn, Jonathan J Deeks, Douglas G Altman.
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Centre for Statistics in Medicine, Institute of Health Sciences,
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Old Road, Headington, Oxford OX3 7LF, UK.
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email mike.bradburn@@cancer.org.uk
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Also see
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--------
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On-line: help for @metan@ (if installed), @meta@ (if installed)
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