Document Type

Capstone Experience

Graduation Date


Degree Name

Master of Public Health



First Committee Member

Dr Edward Peters

Second Committee Member

Dr Ariane Rung

Third Committee Member

Dr Kendra Ratnapradipa


The cohort study is an essential design for investigating associations between a variety of risk factors or exposures and a plethora of health outcomes. However, one of their biggest weaknesses is participant attrition, which can introduce bias and impact validity. Understanding whether this attrition is related to exposure and outcome is a critical aspect of assessing the potential for selection bias. The Women and Their Children's Health (WaTCH) study is a prospective cohort study designed initially to examine the health impacts of exposure to the Deepwater Horizon oil spill. The study has undergone two waves of data collection and is in the middle of a third round of interviews and blood collection. Therefore, examining how loss to follow-up is affected by key baseline characteristics is essential to understand the potential for bias in subsequent analyses. This capstone project sought to examine the association between baseline demographic characteristics, mental health markers (CES-D and K6), physical health, multimorbidity, and exposure to the oil spill with loss to follow-up at Wave 2 of the WaTCH study. We analyzed data from 2,769 Wave 1 participants. Age, race, marital status, income, education and multimorbidity were significantly associated with loss to follow-up between Wave 1 and 2 of the study. High depressive symptoms and high psychological distress were not statistically significantly associated with a higher likelihood of dropping out of the study. These results suggest the possibility that attrition patterns in the WaTCH study may be affected by various demographic factors, which warrants additional research. For a valid longitudinal research design with an accurate interpretation of results, it is essential to comprehend the dynamics of participant retention.

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