The natural progression of disease over time is a consequence of inherited susceptibility (genetic inheritance) and exposure to environmental factors, including lifestyle. As individuals age, depending on their genetic inheritance along with what they do and what they are exposed to, they may develop a chronic disease which progresses over time. It is becoming more widely understood that chronic disease is often the result of multiple factors rather than one single factor.
Different diseases (i.e., cardiovascular disease, metabolic disease, cancers) have different rates of development. In any case, for a long portion of its development, a disease is not clinically apparent although in many cases it could be detected with appropriate attention and diagnostics. Once signs and symptoms develop, it is generally late in the disease development process and the degree of reversibility is reduced and the cost of treatment is increased compared to interventions at an earlier time.
Trajectory of Chronic Disease
There are three time periods over the trajectory of chronic disease.
The right portion of the curve is what we hope to avoid; it is when the burden and cost of poor health takes its toll on individuals and society. Early 21st century health care has made great strides in being able to treat disease once it occurs. Our medical technologies are far better than before, but once disease manifests, intervention is often expensive and minimally effective at reversing the underlying problem. For some people, disease development is unavoidable and here personalizing therapy and disease management can substantially improve health outcomes. But for many, the burden of established chronic disease can be greatly mitigated if it is addressed proactively before it develops.
The middle of the curve is the period during which primary prevention is most important. If an individual’s health risks are known, their providers can begin working with them on what is preventable. This can be done through education about lifestyle changes for health enhancement (like healthy diet and exercise), engaging individuals in their health, continuously monitoring risk markers for disease progression, and at times, medications to minimize disease development.
Furthest to the left of the curve is where the greatest opportunities lie. It is the period before a disease begins to develop and provides the greatest opportunity for improving health. Based on an individual’s characteristics, genetics, and environment, one can begin to quantify his or her disease risks and develop a plan to prevent them. At this point, engaging the individual in lifestyle changes to minimize their disease risks can have the greatest impact. By doing so, health care can focus on shifting the interventions to the left of the curve resulting in a far more efficient and effective health care delivery model.
Proactive, personalized intervention, at any point in the curve should minimize ramification of disease progression. The concept of “shifting the arrow to the left” provides great opportunities for the development of more rational approaches to health care.