Low frequency of hypersensitivity reactions to abacavir in HIV infected patients in a referral center in Bahia, Brazil

Abacavir can cause a multi-systemic hypersensitivity reaction (HSR) in 5–8% of the patients, which is related to HLA-B*57-01 allele. In Brazil, the HLA-B*57-01 screening test became available only in March 2018, several years after abacavir was in use. In this retrospective study we reviewed medical charts of all patients receiving an abacavir-containing regimen to evaluate the frequency of HSR in patients followed at a referral center in Salvador, Brazil. A total of 192 patients who received abacavir were identified, most male (67.1%), black or racially mixed (77.8%), and having diagnosis of a previous AIDS defining conditions (83.7%). Only one patient developed HSR (incidence: 0.52%). The main reasons for abacavir-containing antiretroviral therapy discontinuation were virological failure (28%), adverse effects to other components of the regimen (25%), and simplification of therapy (16%). The low incidence of HSR to abacavir does not support the use of HLA-B*57-01 screening test, in Salvador, Brazil.