Levels of evidence and grading of recommendations  
Strength of recommendation Quality of evidence
A–good I–properly randomized controlled trials
B–moderate II–other published studies
C–poor III–expert opinion
  Carosi G. et al, First Italian Consensus Statement on Diagnosis, Prevention and Treatment of Cardiovascular Complications in HIV-infected Patients in the HAART Era (2006). Infection. 2007 Jun;35(3):134-42.