The purpose and significance of prevalence survey

The prevalence rate, also called the prevalence rate, is the same as the incidence rate, and the score is also used to reflect the prevalence rate. Different from the incidence rate, the molecule of the incidence rate is the number of new and old cases of a certain disease in a certain population at a certain time. Whether it is a new disease or an old disease, as long as the disease does not heal within a certain period of time, it is recorded as the number of cases. However, the molecule of the incidence rate is the number of new cases in the exposed population in a certain period of time. Anyone who has new diseases in the exposed population is called "new cases".

The prevalence rate refers to the old and new cases of a disease in the total population in a specific event. According to the different observation time, it can be divided into two types: period prevalence rate and time-point prevalence rate. In the investigation of chronic diseases, people often think that the prevalence rate is the most suitable index for calculation.

The difference between prevalence rate and incidence rate is that the prevalence rate is the frequency of diseases obtained from cross-sectional surveys, which is usually used to reflect the prevalence rate of chronic diseases with a long course of disease and its impact on people's health. However, incidence refers to the frequency of diseases obtained from incidence reports or cohort studies, which is usually used to reflect the emergence of new cases.

Among them, the two-week prevalence rate, also known as the two-week prevalence rate, is an indicator of health service demand, which has certain guiding significance in clinic: the two-week prevalence rate = the ratio of the number of patients or the number of people/the total number of people surveyed within two weeks (percentage or thousandth rate).

Generally speaking, the two-week prevalence rate = the number of patients or the ratio of patients to the total number of people surveyed within two weeks (percentage or thousandth rate). The reason for setting the two-week prevalence rate is mainly to reduce this inevitable memory bias due to retrospective investigation.