The US National Children's Study must have more funds

Abstract

Environmental factors have a crucial role in determining the health of the world's 2·3 billion children. But exactly which risk factors contribute to childhood chronic disease is unknown. For this reason, US Congress passed the Children's Health Act 2000, which asked for a large national prospective cohort study of environmental influences—including physical, chemical, biological, and psychosocial factors—on children's health and development. The result, the National Children's Study, is an ambitious project that aims to track the health of 100 000 children from birth to their 21st birthday. To do this, the study organisers estimate they will need US$2·7 billion over 25 years, but they have already hit problems securing the necessary funds. The plan is for 101 research centres, located throughout the USA, to recruit 100 000 children from birth. 75 of the centres are in urban locations and 26 are in rural ones; they were selected with a probability-based sampling strategy to ensure that children from a wide variety of social and ethnic backgrounds are included in the study. Eight vanguard centres have been chosen to pilot the study protocol. Assuming everything goes to plan, households near the vanguard centres will start to be screened in 2007. The researchers will identify women who are pregnant, or who are likely to become so by the end of 2011. Each of the centres has been given the target of recruiting 250 newborns a year for 4–5 years. The researchers plan to collect data every 3 months until the child is 5 years old, by phone, email, post, and diaries. They will take samples of blood, urine, hair, saliva, and nail from the child and parents, and will collect air, water, soil, paint, and dust from the local environment. In total, every child will be examined by one of the study staff members on 15 occasions. The first results are expected within 2–3 years. The benefits of such a labour-intensive and expensive process are potentially huge. American children are more likely than ever to develop chronic diseases such as obesity, diabetes, asthma, and behavioural disorders. According to one estimate, the annual disease burden from the ten most common health problems that afflict children is around $400 billion a year in the USA alone. From a purely economic point of view, therefore, the National Children's Study could pay for itself many times over if it reduces this burden by as little as 1% a year. The Framingham Heart Study, on which the National Children's Study is modelled, made a huge contribution to the 42% decrease in mortality rates from cardiovascular disease seen between 1970 and 1990. Identifying the factors that slow down the intellectual development of children could be even more valuable. The National Children's Study is not the first longitudinal cohort study to track childhood development. The Danish National Birth Cohort has recruited 100 000 women early in pregnancy and plans to continue follow-up for decades. However, every mother has been interviewed by telephone only four times, the last interview when the child was 18 months old. Additional follow-up information will be obtained through individual records in population-based disease registries. A similar approach is being used by the Norwegian Mother and Child Cohort Study, in which postal questionnaires and blood samples are used to study 100 000 mothers and their offspring. By contrast, the National Children's Study is far more ambitious: taking samples from children and the environment gives a much greater chance of detecting risk factors for childhood chronic disease. Indeed, WHO is exploring the possibility of doing long-term cohort studies in other countries, including some in the developing world. Healthy children are more likely to attend school and to develop into productive members of society than are children struggling to cope with obesity, asthma, diabetes, and attention-deficit disorders. Unfortunately, because of a lack of funding, the National Children's Study has already been delayed by a year. For the 2005 fiscal year, Congress appropriated less than half the $27 million researchers were counting on, and for the fiscal year 2006 President Bush has requested that Congress appropriate only $12 million—far less than the study needs to stay on track. This shortfall means that up to eight vanguard centres can start recruiting children, but the study is unlikely to expand to include the other 93 centres. This outcome would hamstring the study, the main strength of which is its size and comprehensive sampling strategy. US Congress needs to have the long-term vision to leave a legacy to help future generations of children, not just in the USA but throughout the world.