Data should be entered directly into an electronic database as this is the most efficient method of collating data. If this is not possible, paper data registration forms can be used to enter data initially so that the data can be subsequently entered into a computerized system. Data elements should be coded (e.g. 1=female, 2=male).
To monitor repetition, a surveillance system should record data according to events/presentations/episodes as well as persons. A unique person identification number is necessary to ensure accurate calculation of the number of persons presenting to hospitals after a suicide attempt or self-harm. A unique event number is required to calculate the number of total presentations in a given time period (since several presentations may be made by the same person). In the case of a repeated presentation, a new event number should be generated but the same unique person identification number should be used.