es_from_cases_time function

Convert the number of cases and the person-time of disease-free observation in two independent groups into an incidence rate ratio (IRR)

es_from_cases_time(n_cases_exp, n_cases_nexp, time_exp, time_nexp, reverse_irr)

Arguments

• n_cases_exp: number of cases in the exposed group
• n_cases_nexp: number of cases in the non-exposed group
• time_exp: person-time of disease-free observation in the exposed group
• time_nexp: person-time of disease-free observation in the non-exposed group
• reverse_irr: a logical value indicating whether the direction of the generated effect sizes should be flipped.

Returns

This function estimates IRR.

natural effect size measure	IRR
converted effect size measure	N/A
required input data	See 'Section 5. Incidence Ratio Ratio'
	https://metaconvert.org/input.html

Details

This function estimates the incidence rate ratio from the number of cases and the person-time of disease-free observation in two independent groups.

The formula used to obtain the IRR and its standard error are (Cochrane Handbook (section 6.7.1):

$$logirr = log(\frac{n\_cases\_exp / time\_exp}{n\_cases\_nexp / time\_nexp)}$$ $$logirr\_se = \sqrt{\frac{1}{n\_cases\_exp} + \frac{1}{n\_cases\_nexp}}$$

Examples

es_from_cases_time(
  n_cases_exp = 241, n_cases_nexp = 554,
  time_exp = 12.764, time_nexp = 19.743
)

References

Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (editors). Cochrane Handbook for Systematic Reviews of Interventions version 6.3 (updated February 2022). Cochrane, 2022. Available from www.training.cochrane.org/handbook.