Table 1 The CDC standard performance indicators to assess the usefulness of surveillance system [12]
Indicator | Definition |
|---|---|
Data quality | depends on the completeness and validity of eDEWS data, and the accuracy of its reports. |
Timeliness | refers to the speed or interval between steps in the eDEWS. The time interval between any two sequential steps can be assessed. |
Simplicity | refers to the simple structure and ease in applying the procedure to improve the timeliness of the eDEWS. |
Positive predictive value (PPV) | reflects the proportion of confirmed cases or alerts from the condition under surveillance. eDEWS allows for the calculation of a PPV at the level of case detection depending on the number of alerts generated and the proportion of confirmed alerts as truly under surveillance. |
Sensitivity | The sensitivity of a surveillance system can be considered on two levels. At the level of case reporting, sensitivity refers to the proportion of cases of a disease detected by the surveillance system. Sensitivity also can refer to the system’s overall ability to detect outbreaks, including the ability to monitor changes in the number of cases in a population over time. |
Acceptability | indicates the willingness of health workers and partners to participate in the surveillance system. |
Flexibility | means the ease with which a) information or conditions can be changed as needed, b) eDEWS can accommodate a new disease, c) changes can be made in case definitions, and d) variations can be made in reporting sources. |
Representativeness | defines disease occurrence over time and the characteristics of a covered population. |