Absolute risk reduction: Difference between revisions
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:<math>\mbox{Absolute risk reduction} =\left (\mbox{CER - EER}\right)</math> | :<math>\mbox{Absolute risk reduction} =\left (\mbox{CER - EER}\right)</math> | ||
===Confidence intervals=== | |||
The confidence intervals can be calculated using the method of Daly:<ref name="pmid9554420">{{cite journal| author=Daly LE| title=Confidence limits made easy: interval estimation using a substitution method. | journal=Am J Epidemiol | year= 1998 | volume= 147 | issue= 8 | pages= 783-90 | pmid=9554420 | |||
| url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&retmode=ref&cmd=prlinks&id=9554420 }} <!--Formatted by http://sumsearch.uthscsa.edu/cite/--></ref> | |||
:<math>\mbox{Standard error} =\sqrt{\left(R_1 \times\frac{1-R_1}{N_1}\right) + \left(R_2 \times\frac{1-R_2}{N_2}\right)}</math> | |||
:<math>\mbox{Confidence intervals} = \mbox{Absolute risk reduction} \pm 1.96 \times \mbox{Standard error}</math> | |||
==References== | ==References== |
Revision as of 00:59, 23 November 2009
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In clinical epidemiology and evidence-based medicine, the absolute risk reduction is a measure that compares the frequency of a clinical outcome in group of patients exposed to a factor compared to a control group of patients.[1] This measure should be contrasted with the relative risk reduction.
Most scientific journal articles fail to report absolute measures which may lead to exaggerated perceptions of results.[2]
Calculations
Outcome | ||||
---|---|---|---|---|
Present | Absent | |||
Experimental group | Cell A | Cell B | Total in the experimental group | |
Control group | Cell C | Cell D | Total in the control group | |
Total with the outcome | Total without the outcome |
Confidence intervals
The confidence intervals can be calculated using the method of Daly:[3]
References
- ↑ Barratt A, Wyer PC, Hatala R, et al (2004). "Tips for learners of evidence-based medicine: 1. Relative risk reduction, absolute risk reduction and number needed to treat". CMAJ 171 (4): 353–8. DOI:10.1503/cmaj.1021197. PMID 15313996. Research Blogging.
- ↑ Welch HG et al.Ratio measures in leading medical journals: structured review of accessibility of underlying absolute risks.BMJ. 2006 Dec 16;333(7581):1248. Epub 2006 Oct 23. PMID 17060338
- ↑ Daly LE (1998). "Confidence limits made easy: interval estimation using a substitution method.". Am J Epidemiol 147 (8): 783-90. PMID 9554420.