Which bias is most specifically associated with loss to follow-up in studies?

Which bias is most specifically associated with loss to follow-up in studies?

• A. Selection bias
• B. Information bias
• C. Confounding bias
• D. Attrition bias

Answer: (D)

When participants who discontinue participation differ in important ways from those who continue, the study’s effect estimates can be distorted. This situation defines attrition bias, which happens specifically due to loss to follow-up. If the people who drop out have different outcomes or exposures than those who stay, the observed association may not reflect the true effect in the full population. This differs from selection bias, which is about how participants are chosen or enrolled in the study from the start; information bias, which involves errors in measuring exposure or outcome; and confounding bias, which arises when an extraneous variable related to both exposure and outcome distorts the observed relationship. Attrition bias is the loss-to-follow-up form of bias, making it the best answer for this scenario.

When participants who discontinue participation differ in important ways from those who continue, the study’s effect estimates can be distorted. This situation defines attrition bias, which happens specifically due to loss to follow-up. If the people who drop out have different outcomes or exposures than those who stay, the observed association may not reflect the true effect in the full population.

This differs from selection bias, which is about how participants are chosen or enrolled in the study from the start; information bias, which involves errors in measuring exposure or outcome; and confounding bias, which arises when an extraneous variable related to both exposure and outcome distorts the observed relationship. Attrition bias is the loss-to-follow-up form of bias, making it the best answer for this scenario.