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IRRAD is an Excel spreadsheet that extends the “Axelson adjustment” for binary variables to adjust observed RRs for a (measured or unmeasured) confounding variable when exposure and confounder have multiple categories. IRRAD allows the User to designate a multiplicative or an additive relative risk (RR) model for the joint association of exposure (X) and confounder (C). Additionally, the spreadsheet solves linear equations to define those characteristics that a confounder must have to explain fully or partially an observed association.

- License Agreement
- IndirectRRAdjustment(IRRAD)_NCI_DCEG_ 2018_v1.3.xlsm
- Note: End users will need to enable macros, which are used throughout to create an interactive user interface. All calculations however, are done within the excel worksheets.
*Updated: December, 2018*

- Note: End users will need to enable macros, which are used throughout to create an interactive user interface. All calculations however, are done within the excel worksheets.

The spreadsheet incorporates four approaches to assess confounder effects under either a multiplicative or additive model. These include:

**Binary exposure and binary confounder**: a) find the adjusted RR given the observed RR, P(C=1|X=1) and P(C=1|X=0) [or equivalently the observed RR, P(C=1|X=0) and the odds ratio OR(X,C)]; and b) solve for the necessary OR(X,C) given the observed, adjusted and confounder RRs and P(C=1|X=0);**Categorical exposure and categorical confounder**: find the adjusted RRs for each level of exposure given the observed RRs, the confounder distribution at each level of exposure P(C|X) and confounder RRs at the reference level of exposure;**Categorical exposure and binary confounder**: solve for the conditional distribution of the confounder at each level of X, P(C=1|X), given the observed, adjusted and confounder RRs and P(C=1|X=0);**Categorical exposure and catgorical confounder**: solve for the confounder RRs given the observed RRs, the adjusted RRs and P(C|X).

IRRAD includes the data used for the examples in Lubin et al.

Email: Contact DCEG

- Lubin JH, Hauptmann M, Blair A. Indirect adjustment of relative risks of an exposure with multiple categories for an unmeasured confounder. Ann Epidemiol 2018 In Press

**Note**: IRRAD is currently under review and development for 508-compliance.

U.S. Department of Health and Human Services | National Institutes of Health | National Cancer Institute | USA.gov

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