R: Transform Odds Ratio to Relative Risk

ORToRelRisk {DescTools} | R Documentation

## Transform Odds Ratio to Relative Risk

### Description

Transform a given odds-ratio (OR) to the respective relative risk (RR).

### Usage

    ORToRelRisk(or, p0)

### Arguments

`or` | numeric vector: OR (odds-ratio).
`p0` | numeric vector: incidence of the outcome of interest in the nonexposed group.

### Details

The function transforms a given odds-ratio (OR) to the respective relative risk (RR). It can also be used to transform the limits of confidence intervals.

It uses the formula of Zhang and Yu (1998).

### Value

relative risk.

### Author(s)

Matthias Kohl <matthias.kohl@stamats.de>

### References

Zhang, J. and Yu, K. F. (1998). What's the relative risk? A method of correcting the odds ratio in cohort studies of common outcomes. JAMA, 280(19):1690-1691.

### Examples

    ## We use data from Zhang and Yu (1998)

    ## single OR to RR
    ORToRelRisk(14.1, 0.05)

    ## OR and 95% confidence interval
    ORToRelRisk(c(14.1, 7.8, 27.5), 0.05)

    ## Logistic OR and 95% confidence interval
    logisticOR <- rbind(c(14.1, 7.8, 27.5),
                        c(8.7, 5.5, 14.3),
                        c(27.4, 17.2, 45.8),
                        c(4.5, 2.7, 7.8),
                        c(0.25, 0.17, 0.37),
                        c(0.09, 0.05, 0.14))
    colnames(logisticOR) <- c("OR", "2.5%", "97.5%")
    rownames(logisticOR) <- c("7.4", "4.2", "3.0", "2.0", "0.37", "0.14")
    logisticOR

    ## p0
    p0 <- c(0.05, 0.12, 0.32, 0.27, 0.40, 0.40)

    ## Compute corrected RR
    ## helper function
    ORToRelRisk.mat <- function(or, p0){
      res <- matrix(NA, nrow = nrow(or), ncol = ncol(or))
      for(i in seq_len(nrow(or)))
        res[i,] <- ORToRelRisk(or[i,], p0[i])
      dimnames(res) <- dimnames(or)
      res
    }
    RR <- ORToRelRisk.mat(logisticOR, p0)
    round(RR, 2)

    ## Results are not completely identical to Zhang and Yu (1998)
    ## what probably is caused by the fact that the logistic OR values
    ## provided in the table are rounded and not true values.

[Package DescTools version 0.99.24 Index]