Power and sample size calculations for case-control studies of gene-environment interactions with a polytomous...

Area of Science:

• Epidemiology
• Genetic Epidemiology
• Biostatistics

Background:

• Genetic polymorphisms influence individual susceptibility to environmental exposures.
• Gene-environment interactions are crucial for understanding disease etiology.
• Epidemiologic studies often investigate heterogeneity in exposure susceptibility.

Purpose of the Study:

• To develop a general approach for power and sample size calculations in case-control studies.
• To address scenarios with polytomous exposure variables and non-independent genotype distributions.
• To provide tools for estimating gene-environment interaction parameters.

Main Methods:

• Utilized a general approach for power and sample size calculations.
• Explored various scenarios with polytomous exposure and gene-environment interaction.
• Developed a user-friendly Fortran program for specific calculations.

Main Results:

• Power calculations were insensitive to certain odds ratio assumptions but sensitive to gene frequency.
• Low gene frequency particularly impacts power calculations.
• Detecting small to moderate gene-environment interaction effects necessitates large sample sizes.

Conclusions:

• Accurate power and sample size calculations are vital for gene-environment interaction studies.
• Gene frequency is a critical factor influencing study power.
• Researchers are encouraged to use the provided Fortran program for tailored sample size determination.