, the study found that during the past three decades, high rates of incarceration of black men may have accounted for up to 65% of the loss of follow-up among this group. Conditions such as cardiovascular disease and sickle cell disease are more common among black men than in white men, and have complex factors that influence illness and death. This makes it important for analysts to have access to a large number of cases so that they can draw statistically significant conclusions, say the researchers.
"A black man who begins a research study is less likely to follow up because he is statistically more likely to be jailed or imprisoned during the study than his white counterpart," said the study's first author Emily Wang, M.D., assistant professor at Yale School of Medicine. The impact of incarceration on health outcome studies was far less among white men, white women, and black women.
Government regulations bar study subjects from participating once they are incarcerated, unless the study investigators apply for special permission through their institutional review board (IRB). If studies do not specify otherwise, community-recruited participants who enroll in studies cannot be followed while they are incarcerated. In certain jurisdictions, they cannot be followed after their release.
Wang and her co-authors examined the protocols of a group of studies funded by the National Heart, Lung, and Blood Institute. They looked for studies that had received IRB protocols to follow prisoners, and also looked at how much loss to follow-up there was. They found that none of the studies received IRB approval for prisoner follow up; so the team then estimated how many individuals may have been incarcerated during the time period based on national imprisonment rates.
"We are missing opportunities to study the outcomes of research on this population so treatments can be tailored," Wang added. "It is important that research subjects who are incarcerated be allowed to continue participating in observational research that poses minimal risk to the participants."
Under current circumstances, Wang said the results of longitudinal studies may fail to accurately represent the experience of black populations and may bias estimates of racial disparities by either excluding people in jail or prison or discontinuing longitudinal follow-up at the time of incarceration.