Analysis of the records of over 8,000 patients receiving treatment with the NRTI abacavir has revealed that 5% experienced the potentially life-threatening hypersensitivity reaction to the drug, according to a poster presentation to the 43rd ICAAC which is taking place in Chicago between September 14 - 17th.
Although the 5% incidence of abacavir hypersensitivity reaction reported in this poster is higher than the 3% incidence which was previously though to occur, it is lower than the 7% - 9% incidence reported in some other studies presented to ICAAC this week. It is thought that these studies over represented the extent of allergic reaction to abacavir due to cautious monitoring and reporting by investigators.
Investigators from abacavir’s manufacturer, the UK-based pharmaceutical company GlaxoSmithKline (GSK) conducted a retrospective analysis of all 34 GSK- sponsored abacavir trials with at least 24 weeks of data, which had been completed by the end of 2002.
Cases of hypersensitivity reaction were identified from case notes and from a case report form, a procedure for reporting the hypersensitivity reaction. Variables analysed for an association with abacavir hypersensitivity included demographic details such as age, sex and race, stage of HIV disease, CD4 cell count, HIV viral load, prior anti-HIV therapy, medication used at the same time as abacavir, and laboratory markers including liver function, and levels of alkaline, phosphorus, total bilirubin and creatinine.
Data from 8,038 individuals were examined by the investigators, and a total of 403 cases (5% of total study population) of abacavir hypersensitivity were identified.
In univariate analysis, African or American Hispanic race, being male, CD4 cell count, stage of HIV disease, the use of an NNRTI, AZT or 3TC, geographic location, and year in which treatment with abacavir was started were all identified as having a negative association with the abacavir hypersensitivity reaction.
When these results were subjected to multivariate analysis, African ethnicity (OR 0.52), being male (OR 0.70), and an AIDS diagnosis (OR O.74), were found to reduce the risk of the hypersensitivity reaction occurring (tested to p
Hernandez JE et al. Clinical risk factors for hypersensitivity reactions to abacavir: retrospective analysis of over 8,000 subjects receiving abacavir in 34 clinical trials. 43rd ICAAC, abstract H-2013, Chicago, September 14 - 17th, 2003.