Over the past forty years, NIH funding of prevention research has led to the development of family, school, and community interventions that have vastly increased our ability to prevent virtually all of the most common and costly psychological, behavioral, and physical health problems that undermine
human wellbeing.

Unfortunately, this progress has not contributed to reducing disparities in health. The life expectancy for members of disadvantaged groups, including Black, Hispanic, Native American and rural people is significantly lower than it is for other groups. In fact, these disparities have significantly increased in recent years.

One reason for this state-of-affairs is that not enough research has been conducted to adapt evidence-based preventive interventions for distressed communities and, in turn, test their ability to reduce health disparities. Another is that these disadvantaged communities are harmed by unabated high levels of poverty and discrimination.

To exert a meaningful impact on disparities, we must invest in the development and evaluation of preventive interventions in Black, Hispanic, Native American and rural communities to determine (a) impacts on health outcomes when interventions are appropriately adapted and (b) the extent to which population level disparities narrow.

The Critical Role of Experimental Evaluation

Effective preventive interventions have been developed thanks to hundreds of randomized trials. Researchers have identified at least sixteen different family interventions that can prevent child and adolescent problems including depression, antisocial behavior, and substance use. School based programs have prevented youth smoking, other substance use, as well as antisocial behavior, school dropout, and suicidal behavior. Studies of community-wide interventions have also shown benefit in reducing risk factors for major health disorders such as cancer and diabetes. Additionally, adverse childhood experiences (ACEs), which are denser in disadvantaged communities and mostly preventable, are associated with higher rates of heart disease, stroke, cancer, COPD, diabetes, and suicide.

Randomized trials provide the strongest evidence that a program works because they eliminate the possibility that beneficial effects were due to factors other than the program.

• Unfortunately, NIH funding for randomized trials has declined over the past 15 years.
• In particular, fewer randomized trials are being conducted to evaluate preventive interventions.
• Indeed, only 2.5% of NIH studies involve experimental evaluations of preventive interventions.
• Interventions are often not sufficiently adapted to the needs of disadvantaged communities and, thus, we cannot be sure they will produce the same benefits as have been achieved in more advantaged populations.

Research Needed to Reduce Health Disparities

Differences in life expectancy result from disparities in behavioral and physiological risk factors, such as cigarette smoking, inactivity, hypertension, and diabetes. A vitally important consideration, however, is that these risk factors are more prevalent in disadvantaged communities due to broad social and structural influences on health, including poverty and discrimination. For these reasons, research is needed to develop and experimentally evaluate comprehensive interventions to affect behavioral and physiological risk factors that lead to disparities. At the same time, experimental research is needed to evaluate systems change and policy strategies for reducing poverty, inequities, and discrimination that in large part are the primary determinants of health disparities.

Suggested Policy
The NIH needs to adopt a coordinated, long-term, and trans-institute effort to support extramural research that experimentally develops and evaluates preventive interventions that address the leading risk factors for death and disability that result in health disparities. We recommend the following budgetary emphases for NIH research:

• One line of research to address the above gaps should evaluate the ability of existing research-based interventions to prevent and/or mitigate risk factors for health disparities.
• A second line of research needs to experimentally evaluate strategies for altering the underlying social determinants of health disparities including poverty, discrimination, and economic
  inequality.
• Given the significance of health disparities for the wellbeing of the nation, we recommend to Congress that at least 5% of the NIH research portfolio be devoted to these lines of research.