Healthy worker effect in cohort studies on chronic bronchitis

Pesticide use and chronic bronchitis among farmers in the agricultural health study

“…Tupi and colleagues showed that farmers with chronic bronchitis planned to reduce, finish, or change the line of farm production more than twice as often as healthy farmers and that 37% considered health reasons to be the main determinant of a change in future activities . In a meta-analysis of longitudinal occupational studies of lung function, individuals with chronic bronchitis at enrollment were more likely to leave their occupational cohort than were other members [Radon, et al 2002]. Thus, our results may underestimate the impact of farming exposures, if individuals changed their farm exposures as a result of diagnosis before enrollment.…”

Adolescents’ jobs and the course of dermatitis symptoms throughout puberty

“…Even though only about one-third of the population already had an employment history, the decreasing odds ratio for a new onset of symptoms of dermatitis with longer duration of exposure might already indicate a healthy worker selection bias (34). Therefore, this study shows the necessity to start cohort studies at the beginning of occupational life and take holiday jobs and vocational training on the job into account.…”

Life-expectancy estimations and the determinants of survival after 15 years of follow-up for 81 249 workers with permanent occupational disabilities

“…First of all, all of the cases were actively employed prior to their injury or were healthy workers (34), who would have longer life expectancies in the absence of work-related disability. As the Monte Carlo simulation used the national vital statistics as the reference population, life-expectancy losses would be underestimated.…”