2.2.2 Bottom-up studies

Bottom-up COI studies review all relevant individual illnesses and then estimate the total socioeconomic cost of these illnesses for the given nation. These studies use the medical records of individual patients to estimate the costs for individual patients and then expand those estimates to arrive at the total cost for the entire group of patients affected. While this method affords relatively greater accuracy in estimation than the top-down method, it is, realistically, quite difficult to estimate the national socioeconomic cost due to the sheer volume and complexity of the data on individual patients. There may also be regional disparities in the availability and use of healthcare services, meaning that the resulting data may fail to represent the entire given society.

## 2.3 Value assessment

In general, there are two ways to evaluate and estimate the indirect socioeconomic costs of illnesses (namely, losses of labor and productivity). These are the human capital approach and the willingness-to-pay (WTP) approach [6, 7].
