Effects of time-varying exposures adjusting for time-varying confounders: the case of alcohol consumption and risk of incident human immunodeficiency virus infection.

OBJECTIVE

Discuss issues related to time-varying exposures using as an example the recently meta-analyzed literature (Baliunas et al. in Int J Public Health, 2009) on alcohol consumption and risk of HIV infection.

METHODS

Cataloged sources of bias and imprecision in the context of time-varying exposures.

RESULTS

Confounding, selection, or measurement bias may occur when standard regression approaches are used to estimate effects of time-varying exposures. The reviewed literature on alcohol consumption and HIV infection suffer from one or more of these biases.

CONCLUSIONS

Detailed prospective data and thoughtful implementation of appropriate statistical methods are needed to obtain unbiased estimates of time-varying exposures, such as alcohol consumption.