Healthy user bias explained
The healthy user bias or healthy worker bias is a bias that can damage the validity of epidemiologic studies testing the efficacy of particular therapies or interventions.
Specifically, it is a sampling bias or selection bias: the kind of subjects that take up an intervention, including by enrolling in a clinical trial, are not representative of the general population. People who volunteer for a study can be expected, on average, to be healthier than people who don't volunteer, as they are concerned for their health and are predisposed to follow medical advice,[1] both factors that would aid one's health. In a sense, being healthy or active about one's health is a precondition for becoming a subject of the study, an effect that can appear under other conditions such as studying particular groups of workers. For example, someone in ill health is unlikely to have a job as manual laborer. As a result, studies of manual laborers are studies of people who are currently healthy enough to engage in manual labor, rather than studies of people who would do manual labor if they were healthy enough.
References
- Shrank. William H.. Patrick. Amanda R.. Alan Brookhart. M.. May 2011. Healthy User and Related Biases in Observational Studies of Preventive Interventions: A Primer for Physicians. Journal of General Internal Medicine. 26. 5. 546–550. 10.1007/s11606-010-1609-1. 0884-8734. 3077477. 21203857.
Further reading
- 10.1093/occmed/49.4.225. A review of the healthy worker effect in occupational epidemiology. 1999. Li . C. -Y. . Sung . F. -C. . Occupational Medicine. 49. 4. 225–9 . 10474913.
- 10.2203/dose-response.09-019.Fornalski. The Healthy Worker Effect and Nuclear Industry Workers. Dose-Response. 8. 2. 125–147. 2010 . Fornalski . K. W. . Dobrzyński . L.. 20585442 . 2889508.
- McMichael, A. J. (1976). Standardized mortality ratios and the “healthy worker effect”: Scratching beneath the surface. Journal of Occupational Medicine, 18, 165–168. doi:10.1097/00043764-197603000-00009
- Tabuchi T., Nakayama T., Fukushima W., Matsunaga I., Ohfuji S., Kondo K., Oshima A. . 2015 . Determinants of participation in prostate cancer screening: A simple analytical framework to account for healthy-user bias . Cancer Science . 106 . 1. 108–114 . 10.1111/cas.12561 . 25456306 . 4317786 .
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