Evolving Methods for Inference in the Presence of Healthy Worker Survivor Bias

• Published in: Epidemiology (Cambridge, Mass.) Mass.), 2015-03, Vol.26 (2), p.204-212
• Main Authors: Buckley, Jessie P., Keil, Alexander P., McGrath, Leah J., Edwards, Jessie K.
• Format: Article
• Language: English
• Subjects: Bias; Data Interpretation, Statistical; Healthy Worker Effect; Humans; Methods; Models, Statistical; Occupational Diseases - etiology; Occupational Diseases - mortality; Occupational Exposure - adverse effects
• ISSN: 1044-3983; 1531-5487
• DOI: 10.1097/EDE.0000000000000217

Healthy worker survivor bias may occur in occupational studies due to the tendency for unhealthy individuals to leave work earlier, and consequently accrue less exposure, compared with their healthier counterparts. If occupational data are not analyzed using appropriate methods, this bias can result in attenuation or even reversal of the estimated effects of exposures on health outcomes. Recent advances in computing power, coupled with state-of-the-art statistical methods, have greatly increased the ability of analysts to control healthy worker survivor bias. However, these methods have not been widely adopted by occupational epidemiologists. We update the seminal review by Arrighi and Hertz-Picciotto (Epidemiology.1994; 5: 186–196) of the sources and methods to control healthy worker survivor bias. In our update, we discuss methodologic advances since the publication of that review, notably with a consideration of how directed acyclic graphs can inform the choice of appropriate analytic methods. We summarize and discuss methods for addressing this bias, including recent work applying g-methods to account for employment status as a time-varying covariate affected by prior exposure. In the presence of healthy worker survivor bias, g-methods have advantages for estimating less biased parameters that have direct policy implications and are clearly communicated to decision-makers.