The Pediatric Drug Surveillance ("PeDS") Program is an epidemiologic study of the clinical effects of drugs in hospitalized children. The objectives of this research project are to study the acute and long-term clinical effects of drugs in the pediatric population; in particular, we intend to identify previously unsuspected acute effects of drugs and previously unsuspected relationships between specific diseases and drugs used on an out-patient basis. In addition, the project seeks to evaluate patient factors that may influence the outcome of drug therapy. Given the relative lack of information about drug effects in the newborn, this project intends to study the effects of drugs in the newborn with particular emphasis. This project also seeks to address certain methodologic issues related to intensive drug surveillance; for example, we intend to evaluate both the feasibility and utility of conducting drug surveillance in community hospitals. Finally, to increase the efficiency of in-hospital intensive drug surveillance, the project will develop methods that utilize existing hospital computer files to obtain information currently obtained through other means.