Surveillance of acute complications of new therapies

In its essence, surveillance is the continuous gathering, analysis, and dissemination of data to those who need to know for the purposes of disease control. To understand the complications of new therapies, data concerning the type and number of complications (numerator) and the population at risk for complications (denominator) must be gathered. Information about the expected rates of complications among comparison populations must be known to place the observed rates into perspective. Such data may be developed through active or passive reporting systems, clinic-based surveillance, follow-up of sentinel events, and registries. An investigation of mortality among users of continuous subcutaneous insulin infusion (CSII) pumps is used as an example.