Subclinical disease is another concept of health, also known as "asymptomatic disease". It is believed that disease is a process of life phenomenon that changes conditions. In the process of disease, not only the body is damaged and disordered, but also the physiological reaction of defense, adaptation and compensation will appear. This kind of pathological reaction and physiological reaction are inevitably combined in the process of disease, which is a process and outcome that is difficult to be divided artificially.
The difference between "subclinical disease" and "sub-health state" is that the former has no clinical symptoms and signs, but there is clinical evidence of physiological compensation or pathological changes. For example, "asymptomatic ischemic heart disease" can have no clinical symptoms, but there are diagnostic basis such as ECG changes.