A special Lancet series focused on the health of Americans provides a closer look at the state of health in the U.S., particularly the growing challenge of curbing chronic diseases, the slowing of health expenditure in the U.S., and the potential opportunities afforded by the Affordable Care Act (ACA) to improve public health.

In comparison with other high-income countries, the U.S. is less healthy in areas such as heart disease, diabetes, obesity and chronic lung disease, according to a report on chronic diseases by researchers at the Centers for Disease Control and Prevention (CDC). Half of all adults in the U.S. suffer from at least one chronic condition such as heart disease, obesity and diabetes, with over a quarter of adults suffering from two or more. The report highlights the fact that the majority of these chronic conditions are caused by largely preventable risk factors including the use of tobacco and alcohol, poor diet, physical inactivity and uncontrolled high blood pressure. The report also notes that Medicare enrollees – many of whom are over 65-years-old – account for $300 billion in health care spending, with 90 percent accounted by people with two or more chronic conditions.

Despite the large number of people with chronic diseases, the extent of fragmentation of the U.S. system, the power of vested interests, and other factors, a separate report suggests that that growth in U.S. health expenditures slowed significantly between 2000 and 2011, bringing the growth rate of the country's health budget closer in line with other high-spending countries. The results of the study show health expenditure growth in the U.S. was around seven percent in 2002 compared to an average of just over three percent in other countries. By 2011 however, health expenditure growth in the U.S. declined to about one percent. The report authors note that such a decrease is particularly striking considering U.S. health reform efforts have expanded health care coverage to a wider proportion of the population. However, while progress has been made in reducing the disparity between the country's health care spending, the authors warn that any future economic recovery might reverse the course that has been made in recent years.

Meanwhile, in another report, researchers found that the ACA has the potential to advance public health in the U.S. by supporting increased emphasis on prevention and reversing the division between public health and private health care services. In addition to the ACA increasing the proportion of people in the U.S. covered by medical insurance, the authors of the report argue that the structural and financing reforms introduced in the law will be able to help U.S. health care transition from a system largely focused on treatment of illness to a system that includes disease prevention, health promotion, early detection and public health as integral components. Andrew Rein, formerly of the CDC, and a study co-author notes, "The new law represents a historic opportunity for prevention and public health by establishing the first National Prevention Strategy, adding substantial new funding for prevention and public health programs, and promoting the use of proven clinical preventive services by removing barriers."

Finally, a corresponding viewpoint explores the role of the CDC in promoting and improving global health. The authors describe the CDC's long-standing engagement in global health and its focus on strengthening global health capacity, improving global health security, and broadening the organization's capacity. They explain, "the CDC focuses on the protection of Americans and improvements in the health and capacity of people worldwide through partnerships with ministries of health, other U.S. Government agencies, nongovernmental organizations, and multilateral organizations. The goal of these efforts is to improve health and strengthen capacity while striving for a world more secure from emerging threats."