Prison inmates are not just at increased risk for infectious diseases like HIV, as previous studies have shown, but also for heart-related conditions, new Yale research has found.
The study, published last week in Archives of Internal Medicine, found that former inmates are more likely to suffer from high blood pressure or hypertension, a dangerous thickening of the heart’s left ventricle, in young adulthood than those with no history of incarceration. This association persisted even after adjusting for confounding factors such as substance abuse, race, poverty and prior health conditions, the team found; in fact, the normal risk factors for high blood pressure, such as smoking, alcohol and drug use, and obesity, were found to be unrelated to the high blood pressure observed among the study’s participants.
“It’s not that they’re black or poor or uneducated,” said Dr. Emily Wang, professor at the Yale School of Medicine and lead author on the study. “The association between jail time and hypertension is significant.”
To conduct the study, Wang, in collaboration with researchers from University of California San Francisco, analyzed data from the Coronary Artery Risk Development in Young Adults (CARDIA) study — a cohort of 4,350 young adults, aged 18 to 30 years. Of the participants, black men and less educated participants, who were most likely to have history of prior incarceration, showed the most pronounced association between hypertension and incarceration, according to the study.
Considering that the association cannot be explained by prior health history, race or poverty, the next step is explain this counter-intuitive result, Wang said.
“Our next step is to look into the mechanism behind this association,” she said. “Anecdotally, from patients’ stories, who were incarcerated and released, it might be that stress or a disregulation of stress hormones over time might be driving this association.”
Dr. Kirsten Bibbins-Domingo, a professor at UCSF and co-author on the study, said the team is now investigating this hypothesis.
“We are examining the contribution of the stress of incarceration and other psychosocial factors as an explanation of these findings,” she said.
The study also found inmates had a slightly greater risk for developing left ventricular hypertrophy, a thickening of the wall of the heart’s left ventricle, which can lead to heart failure. Although it was found that 2 percent of participants with a history of incarceration developed left ventricular hypertrophy compared to 0.6 percent among those with no history of incarceration, these results were not statistically significant, Wang said.
“That’s not to say that they aren’t associated,” Wang argued. “We just don’t have the numbers to determine that yet.”
Another important factor driving the study was availability of health care in prison.
Wang said she intends to use the findings to inform a public intervention that would provide prisoners with the necessary resources to reduce their risk for hypertension.
“For me, one obvious intervention point would be when people are initially incarcerated,” she said. “That’s the time to teach people about chronic medical conditions — how to diet, exercise, and give them the tools for risk reduction so that they can take them back to their communities when they are released.”
Wang and Bibbons-Domingo said they hope to continue their research to determine whether repeated exposure to incarceration has an even stronger correlation with hypertension than the one observed in the study.