statistics review 11 assessing risk统计回顾11风险评估.pdf

Available online /content/8/4/287 Review Statistics review 11: Assessing risk 1 1 2 Viv Bewick , Liz Cheek and Jonathan Ball 1Senior Lecturer, School of Computing, Mathematical and Information Sciences, University of Brighton, Brighton, UK 2Senior Registrar in ICU, Liverpool Hospital, Sydney, Australia Corresponding author: Viv Bewick, v.bewick@brighton.ac.uk Published online: 30 June 2004 Critical Care 2004, 8:287-291 (DOI 10.1186/cc2908) This article is online at /content/8/4/287 © 2004 BioMed Central Ltd Abstract Relative risk and odds ratio were introduced in earlier reviews (see Statistics reviews 3, 6 and 8). This review describes the calculation and interpretation of their confidence intervals. The different circumstances in which the use of either the relative risk or odds ratio is appropriate and their relative merits are discussed. A method of measuring the impact of exposure to a risk factor is introduced. Measures of the success of a treatment using data from clinical trials are also considered. Keywords absolute risk reduction, attributable risk, case–control study, clinical trial, cross-sectional study, cohort study, incidence, number needed to harm, number needed to treat, odds ratio, prevalence, rate ratio, relative risk (risk ratio) Introduction unexposed group. For the data given in Table 1, if the As an example, we shall refer to the findings of a prospective presence of the C allele is regarded