March 6, 2013 — To ensure that public health interventions that can save lives and improve overall health actually reach people, epidemiologists must do two things. They must provide clear evidence of the need for such interventions. They must also convince policymakers to then take action on the evidence.
This was the theme addressed at a symposium on “translational epidemiology” on February 20, 2013, hosted by the Harvard School of Public Health (HSPH) Department of Epidemiology.
Speakers included Anna Giuliano, director of the Center for Infection Research in Cancer at the Moffitt Cancer Center in Florida, who spoke about the human papilloma virus (HPV) vaccine and the need to offer it to boys as well as girls; and Cesar Victora, emeritus professor of epidemiology, Federal University of Pelotas, Brazil, and president of the International Epidemiological Association, who discussed the importance of providing better nutrition to young children in low- and middle-income countries.
In his opening remarks, HSPH epidemiology professor George Seage said members of HSPH’s Department of Epidemiology are increasingly focusing on translational work, which aims to apply research findings into real-world public health interventions. The challenge in many cases is to determine the most cost-effective approach to scaling up interventions, and how to best design studies to measure the long-term effectiveness of the interventions, Seage said.
Said Giuliano, “What really needs to drive us is to make sure we’re posing questions and hypotheses that will allow us to do something and make a difference in terms of public health. It’s often very difficult to actually achieve that.”
Using the HPV vaccine to combat multiple diseases
Giuliano described how numerous epidemiological studies in the 1980s and 1990s provided solid evidence pinpointing HPV as the primary cause of cervical cancer. This evidence, in turn, led to the development of the HPV vaccine. The vaccine has been extremely effective in preventing cervical cancer and other diseases; for example, after Australia initiated a vaccination program for girls in 2007, the proportion of women under age 21 with genital warts dropped from about 14% to nearly zero in a five-year period, an outcome Guiliano called “remarkable.” She called the development and use of the vaccine an encouraging example of translational epidemiology in action.
More recent evidence suggests that HPV is as dangerous for men as it is for women, Giuliano said. A number of studies have linked HPV with various cancers in men—penile, anal, and head and neck—and these ailments are on the rise. Giuliano presented data from her landmark randomized trial, published in the New England Journal of Medicine in 2011, showing a dramatic decline in the incidence of anal cancers among men receiving the HPV vaccine. These studies provide “evidence of causality,” which Giuliano said is key to getting policymakers “to finally understand the importance of disseminating vaccine not just to females but also to males.” Scientists continue to gather information toward this end, she said.
The importance of birth cohorts
Victora has overseen long-term data collection from three different birth cohorts in Pelotas, Brazil since 1982. He and colleagues collected periodic data from each cohort about how the children fared in terms of a number of factors, including growth; nutrition and body composition; risk factors for chronic diseases; mental health; and human capital—things like schooling, income, and intelligence.
In 2006—knowing that larger data pools would lend more validity to study results and thus be more likely to influence policy—Victora helped bring together colleagues involved in birth cohort research from four other countries to form COHORTS (Consortium of Health Orientated Research in Transitioning Societies). “There are lots of birth cohort publications in the western countries,” he said. “But the results we get from high-income countries may be different than the ones we get from low-income countries.”
Various analyses using pooled data from the five cohorts showed that undernutrition in utero and in the first two years of life were detrimental to children’s subsequent growth and health in low- and middle-income countries (LMICs), where children are often born underweight. “In LMICs, growth falters in the first two years,” Victora said. “This is the window of opportunity for nutrition interventions.”
Children who didn’t gain enough weight in early life faced an array of negative consequences, including increased risk of chronic diseases, higher blood pressure and BMI, lower income or assets, and less schooling.
Victora said evidence from the birth cohort studies in the Philippines and in Brazil helped convince government officials in those countries to promote breastfeeding. It’s important, he added, to continue to convince governments “that investing in early nutrition will pay off in the long term. It may take 15 or 20 years, but it’s a long-term investment in national economic development.”
photos: Aubrey LaMedica