Objective-To evaluate the link between antidepressants and suicidal behavior and ideation (suicidality) in youth, adverse events from pediatric clinical trials were classified in order to identify suicidal events. The authors describe the Columbia Classification Algorithm for Suicide Assessment (C-CASA), a standardized suicidal rating system that provided data for the pediatric suicidal risk analysis of antide-pressants conducted by the Food and Drug Administration (FDA).Method-Adverse events (N=427) from 25 pediatric antidepressant clinical trials were systematically identified by pharmaceutical companies. Randomly assigned adverse events were evaluated by three of nine independent expert suicidologists using the Columbia classification algorithm. Reliability of the C-CASA ratings and agreement with pharmaceutical company classification were estimated.Results-Twenty-six new, possibly suicidal events (behavior and ideation) that were not originally identified by pharmaceutical companies were identified in the C-CASA, and 12 events originally labeled as suicidal by pharmaceutical companies were eliminated, which resulted in a total of 38 discrepant ratings. For the specific label of "suicide attempt," a relatively low level of agreement was observed between the C-CASA and pharmaceutical company ratings, with the C-CASA reporting a 50% reduction in ratings. Thus, although the C-CASA resulted in the identification of more suicidal events overall, fewer events were classified as suicide attempts. Additionally, the C-CASA ratings were highly reliable (intraclass correlation coefficient [ICC]=0.89).Address correspondence and reprint requests to Dr. Posner, Division of Child Psychiatry, Columbia University/New York State Psychiatric Institute, 1051 Riverside Dr., Unit 74, New York, NY 10032; posnerk@childpsych.columbia.edu. CME Disclosure Dr. Posner has received funding from the FDA to develop the suicidality classification system used in their antidepressant safety analysis. Subsequently, as part of an effort to help execute the FDA adult suicidality classification mandates that followed this FDAsponsored pediatric study, Dr. Posner has had research support from GlaxoSmith-Kline, Forest Laboratories, Eisai, Inc., AstraZeneca, Johnson and Johnson, Abbott Laboratories, Wyeth, Organon USA, Bristol-Myers Squibb, Sanofi-Aventis, Cephalon, Novartis, Shire Pharmaceuticals, and UCB Pharma. Dr. Oquendo has received funding from NIMH, National Institute on Alcohol Abuse and Alcoholism, Moody's Foundation, American Foundation for Suicide Prevention, and Eli Lilly (unrestricted educational grant); she has also served as a consultant to Pfizer. Dr. Stanley has received fluoxetine/placebo for a randomized controlled trial from Eli Lilly. Mr. Davies is a shareholder with Merck, Pfizer, Wyeth, GlaxoSmithKline, Johnson and Johnson, Amgen, and Bard. Dr. Gould reports no competing interests. APA policy requires disclosure by CME authors of unapproved or investigational use of products discussed in CME programs. Offlabel use of m...