The aim of the PREDICT-1 study was to determine the clinical utility of the 
pharmacogenetic test identifying HLA-B*5701 to reduce the incidence of 
hypersensitivity reaction to abacavir, diagnosed clinically and with 
immunological confirmation, as well as to reduce unwarranted withdrawal of this 
drug. In the PREDICT-1 study, 1,956 patients were randomized to be screened for 
HLA-B*5701 before starting abacavir treatment (excluding participants who were 
HLA-B*5701-positive) or to receive abacavir without knowing their HLA-B*5701 
status under conventional clinical monitoring. The prevalence of 
HLA-B*5701-positivity was 5.7%. In the group that underwent prospective 
screening, no hypersensitivity tests with immunological confirmation (by 
positive epicutaneous patch testing) were observed compared with an incidence of 
2.7% in the group undergoing standard follow-up. The sensitivity of prospective 
screening in predicting immunologically confirmed hypersensitivity reaction to 
abacavir was 100% and its negative predictive value was 100%. The number of 
clinically suspected hypersensitivity reactions to abacavir was also lower in 
the screened group (3.4% versus 7.8% in the group undergoing conventional 
follow-up). The sensitivity of epicutaneous patch testing for immunological 
confirmation was 100%.