title: Strength of study evidence examined by the FDA in premarket approval of cardiovascular devices.
abstract: BACKGROUND
  Medical devices are common in clinical practice and have important effects on morbidity and mortality, yet there has not been a systematic examination of evidence used by the US Food and Drug Administration (FDA) for device approval.
  
  
  OBJECTIVE
  To study premarket approval (PMA)--the most stringent FDA review process--of cardiovascular devices and to characterize the type and strength of evidence on which it is based.
  
  
  METHODS
  Systematic review of 78 summaries of safety and effectiveness data for 78 PMAs for high risk cardiovascular devices that received PMA between January 2000 and December 2007 [corrected].
  
  
  METHODS
  Examination of the methodological characteristics considered essential to minimize confounding and bias, as well as the primary end points of the 123 studies supporting the PMAs.
  
  
  RESULTS
  Thirty-three of 123 studies (27%) used to support recent FDA approval of cardiovascular devices were randomized and 17 of 123 (14%) were blinded. Fifty-one of 78 PMAs (65%) were based on a single study. One hundred eleven of 213 primary end points (52%) were compared with controls and 34 of 111 controls (31%) were retrospective. One hundred eighty-seven of 213 primary end points (88%) were surrogate measures and 122 of 157 (78%) had a discrepancy between the number of patients enrolled in the study and the number analyzed.
  
  
  CONCLUSIONS
  Premarket approval of cardiovascular devices by the FDA is often based on studies that lack adequate strength and may be prone to bias.
authors.affiliation: Division of Cardiology, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143-0124, USA.
authors.forename: Sanket S
authors.initials: SS
authors.lastname: Dhruva
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Bero
authors.forename: Rita F
authors.initials: RF
authors.lastname: Redberg
mesh_terms: D015982:Bias; D002309:Cardiology / Q000295:instrumentation*; D002986:Clinical Trials as Topic; D018795:Device Approval; D023381:Endpoint Determination; D004869:Equipment Safety; D006801:Humans; D014481:United States; D014486:United States Food and Drug Administration