While common and costly, most chronic diseases are substantially preventable and amenable to improved management for better health outcomes. Behavioral risk factors and clinical precursors for cardiovascular disease and chronic lung disease are well characterized. The major modifiable risk factors for CVD are a diet high in saturated fat and sodium, smoking, high blood cholesterol, high blood pressure, physical inactivity, obesity and overweight, and diabetes mellitus (AHA, 2009; Roger et al., 2010). For COPD, the single most important risk factor is smoking (Ezzati and Lopez, 2003); other risk factors include occupational exposures, environmental tobacco smoke, other indoor air pollutants, outdoor air pollutants, respiratory tract infections, asthma, physical inactivity, poor nutrition, low socioeconomic or educational status, and genetic susceptibility (Eisner et al., 2010; Salvi and Barnes, 2009; Svanes et al., 2010). While a number of sources of data exist, there is no systematic, integrated, and timely tracking and reporting of these behaviors and conditions across different geographic settings or population subgroups in the United States. Additionally, the monitoring of acute clinical events and chronic disease management is fragmented and incomplete. These gaps have detracted from our ability to target focused and effective local and national action to improve health.
Surveillance systems are constructed to routinely inform public health and clinical practitioners, as well as policy makers, other stakeholders, and the general public, of the scope, magnitude, and cost of a health problem in order to regularly influence priority setting, program development, and evaluation of services or policies. The ultimate goal of these monitoring systems is to use information gleaned from surveillance data to take action to reduce morbidity and mortality and improve health, within a framework of finite resources used in an efficient and cost-effective way. Periodic evaluation of the effectiveness and efficiency of surveillance systems in disseminating useful information and impacting decision making is recognized as being intrinsically important (CDC, 2001).
Historically, surveillance systems concentrated on notifiable1 conditions or diseases, for which states required healthcare providers and laboratories to report diseases and conditions of public health interest to a local or state authority (Goodman et al., 2006). Although the quality, cost, and utility of these systems have varied, clear mechanisms for reporting notifiable conditions are typically established in statute, responsibilities are delineated, and the number of involved stakeholders is somewhat circumscribed. In addition, notifiable conditions tend to have characteristics that facilitate easier reporting, such as reliable and specific laboratory tests, discernible communicable threats to public health, and immediately actionable public health interventions. Perhaps most importantly, the objectives of these surveillance systems typically have been quite focused, based on counting cases rather than on estimating rates, and often centered on control of further disease transmission.
In the past 30 years, surveillance systems have expanded in scope and mechanism to also track non-notifiable conditions, particularly cancer registries for surveillance of malignant neoplasms. These surveillance systems have also expanded to include common, multifactorial diseases such as cardiovascular and chronic lung diseases. The tracking of disease events for these diseases is more difficult because of the challenges of disease definition, ascertainment, and differences in access to care, changes in clinical practice, multiple care providers, and lack of perceived threat of disease transmission. Tracking of health events themselves is insufficient because prevention of diseases with complex, multiple contributing factors requires regular collection of surveillance data on the diseases and their multifaceted causes. Prevention efforts require systematically collected information on trends and population distributions of a range of modifiable health behaviors, clinical preventive service use, and disease precursors themselves. Precise information on the denominator population from which the cases occur is also needed, but it is often challenging to obtain. Due to the chronic and debilitating nature of disease, as well as costs of care, indicators tracking the short- and more long-term outcomes of chronic disease management are also critically important.
1 A notifiable disease is “a disease that, by statutory requirements, must be reported to the public health authority in the pertinent jurisdiction when the diagnosis is made. A disease deemed of sufficient importance to the public health to require that its occurrence be reported to health authorities” (Last, 2001). The Council of State and Territorial Health Epidemiologists works with the CDC to regularly update the list of notifiable diseases.