Evidence based medicine: concerns of a clinical neurologist

Level of evidence: Level 1 Data from randomised trials with low false positive ( ) and low false negative ( ) errors Level 2 Data from randomised trials with high false positive ( ) or high false negative ( ) errors Level 3 Data from randomised concurrent cohort studies Level 4 Data from randomised cohort studies that use historical controls Level 5 Data from anecdotal case series Strength of treatment recommendations: Grade A Supported by level 1 evidence Grade B Supported by level 2 evidence Grade C Supported by level 3, 4, or 5 evidence www.jnnp.com