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Determinants of and healthcare utilization associated with early discontinuation of abacavir: A case of genetic screening

Phillips, E.J., Yip, B., Hogg, R.S. and Montaner, J.S.G. (2005) Determinants of and healthcare utilization associated with early discontinuation of abacavir: A case of genetic screening. In: 7th International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV, 13 - 16 November 2005, Dublin, Ireland.


BACKGROUND: Abacavir hypersensitivity reaction (ABC HSR) is the most common reason for the early and permanent discontinuation of this drug. Objectives: To look at determinants of early and permanent discontinuation of ABC and examine subsequent healthcare utilization and treatment outcomes.

METHODS: A population-based cohort study was conducted using available drug and utilization data from the drug treatment program at the BC Centre for Excellence for patients who started abacavir between March 1998 and July 2004. Early discontinuation potentially associated with ABC HSR (EDABC) was defined as those stopping abacavir within 3 months with a diagnosis of ABC HSR or stopping abacavir within 1 month without a specified history. Determinants examined included age, gender, ethnicity, hepatitis C status, injection drug use, treatment experience, concurrent ART, baseline CD4+, viral load and physician experience. Utilization and outcome variables examined included physician visits, hospitalization data, laboratory utilization and time to viral load <500 copies/ml. Logistic regression analyses were performed to examine determinants, outcomes and healthcare utilization associated with EDABC.

RESULTS: A total of 171/1448 (11.8%) of patients ever on abacavir met the definition for EDABC. EDABC patients had physicians with higher experience as measured by the median number of previously treated HIV patients (147 vs 104; P=0.012). EDABC was more common in patients started on abacavir after 2001 or later versus during or before 2001 [87/596(14.6%) vs 84/852(9.9%); P=0.006]. In multivariate analysis only baseline viral load >100000 copies/ml, treatment naïve status and absence of AIDS diagnosis were associated with EDABC. The time to VL <500 copies/ml was significantly longer in patients who had EDABC versus abacavir continuation (131 vs 81 days; P<0.001). EDABC patients were more likely to seek emergency or specialist care within 30 days of starting treatment [24/93(25.8%) vs 129/802(16.1%); P=0.018] and had significantly higher costs for these services within the first 60 days of starting abacavir (P=0.014).

CONCLUSION: EDABC is common, associated with higher and more costly healthcare utilization and its incidence appears to have increased with heightened awareness of ABC HSR. Since ABC HSR is the major reason for permanent EDABC this supports the case for genetic screening programs.

Publication Type: Conference Item
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