A developmental pediatrician and medical historian, Brosco, professor of pediatrics and Associate Director of the Mailman Center, refocused his research to find a precise answer to Shiver’s question, which goes to the heart of the current debate on how best to improve health in the 21st century. On April 29, JAMA Pediatrics published part of the answer by highlighting his latest study, which examines the relationship between medical interventions in early childhood and the increasing prevalence of later intellectual disability, as an Online First article.
Building on their previous work, Brosco and his collaborators specifically found that, by the year 2000, low birth weight was associated with approximately 10 percent to 15 percent of the total prevalence of intellectual disability and that, among medical technologies introduced since 1950, the treatment of low birth weight (LBW) babies in neonatal care units was the most significant contributor to the increased prevalence of intellectual disability (ID).
“In the first third of the 20th century the predominant causes of ID were infections and metabolic conditions, and infant mortality was greater than 100 deaths per 1000 live births. By 1960, overall infant mortality dropped to 23.3 per 1000, yet remained high for LBW infants,’’ the study says. “Since 1960, infant mortality rates have declined for all groups, most dramatically for smaller infants, while the number of LBW infants has increased. These trends led, by the year 2000, to an association with LBW in approximately 10% to 15% of children with ID.”
Brosco and his co-authors make it clear they are not impugning the dedicated professionals whose remarkable work in neonatal intensive care units has saved thousands of lives. Rather, they sought to explore the limits of the century-old biomedical model that aimed to reduce intellectual disability – once known as mental retardation – by 50 percent by 2000 with medical interventions that improved the health of individual patients. They suggest that social and public health solutions that address the social determinants of health would improve the aggregate health of the population, and be a more effective approach to curtailing intellectual disability.
“For example, there is evidence in the United States and internationally that broad social interventions, such as lead abatement and improved nutrition, have done more to decrease the prevalence of ID than specific medical interventions,” the authors wrote, concluding that, “The challenge of the 21st century will be to address the factors that improve developmental outcomes for all children.” Among the factors they cite are preconception risks, such as substance abuse.
Titled “Impact of Specific Medical Interventions in Early Childhood on Increasing the Prevalence of Later Intellectual Disability,” the study builds on previous research Brosco and Lee Sanders, M.D., a former Miller School faculty member now at the Center for Health Policy and Primary Care Outcomes Research at Stanford University, published in the Archives of Pediatrics & Adolescent Medicine (now JAMA Pediatrics) in 2006 to answer a single question: What was the impact of the federal government’s commitment to biomedical solutions to prevent new cases of intellectual disability?
Based on a review of medical literature and other data from 1950 through 2000, that study found that specific medical interventions, such as newborn screening for congenital thyroid deficiency and the genetic disorder phenylketonuria, which if detected can be controlled with diet, had decreased intellectual disability by approximately 16 percent. The authors attributed that significant but relatively small improvement to the fact that specific medical conditions account for a relatively small fraction of the total cases of intellectual disability.
In that study, the authors also noted that, since infant and child deaths have become increasingly rare over the past half century, intellectual disability is a more accurate measure of public health than infant mortality. Asking the corollary question – did medical interventions add to the number of cases of intellectual disability? – in the latest study, Brosco, Sanders, and co-authors Monica Dowling, Ph.D., assistant professor of pediatrics, and Ghislaine Guez, M.D., M.B.A., a Miller School graduate, raise the same argument, noting that, today, intellectual disability “may be a more useful indicator of public health in the United States.”
They also renewed the assertion that addressing the social determinants of health is a more effective strategy for curtailing intellectual disability than medical intervention.
“This study and related work also reveal the need to reexamine our nation’s century-long focus on specific medical interventions, as opposed to social or public health interventions, as the key to improving child and maternal health,” the authors wrote.
Brosco’s research was supported by a Robert Wood Johnson Foundation Generalist Scholar Award and an Arsht Distinguished Ethics Faculty Award.
University of Miami