In a prospective cohort study of adults in Germany, investigators found that sedentary individuals (“exposed) were at greater risk of incident cardiovascular disease over the next 10 years as compared to those that exercised regularly (the unexposed).

 In a prospective cohort study of adults in Germany, investigators found that sedentary individuals (“exposed) were at greater risk of incident cardiovascular disease over the next 10 years as compared to those that exercised regularly (the unexposed). The risk ratio observed for this association was 2.3. However, in this study 20% of cohort members were lost to follow-up over the course of the 10-year study, with rates of loss to follow-up higher among those that are both sedentary and more likely to develop cardiovascular disease. Would you expect the results of this study to be biased? Which would you expect the bias to be; a) upward or downward (but not sure which), b) towards the null, or c) not present.