10th International Workshop on Adverse Drug Reactions and Lipodystrophy in HIV 6-8 November 2008, London, UK

METABOLIC PROFILE OF TWO FIXED-DOSE NUCLEOSIDE ANALOGUE COMBINATIONS (TENOFOVIR/EMTRICITABINE VERSUS ABACAVIR/LAMIVUDINE): BICOMBO MET, A SUBSTUDY OF THE BICOMBO STUDY

Antiviral Therapy 2008; 13(Suppl. 4):A7 (abstract no. O-08)

M Saumoy¹, J Ordoñez², P Barragan¹, E Martinez³, E Ribera⁴, R Bonet², H Knobel⁵, E Negredo⁶, JM Gatell³ and D Podzamczer^1
1Hospital de Bellvitge, Barcelona, Spain; ²Hospital Sant Pau, Barcelona, Spain; ³Hospital Clinic, Barcelona, Spain; ⁴Hospital Vall d`Hebron, Barcelona, Spain; ⁵Hospital del Mar, Barcelona, Spain; ⁶Hospital Germans Trias, Barcelona, Spain

BACKGROUND: Antiretroviral agents might be associated with unfavourable metabolic profiles that contribute to an increase in cardiovascular (CV) risk, although new agents with a lower metabolic impact have been developed. The objective of this study was to compare the metabolic profile and estimated CV risk of two fixed-dose nucleoside analogue combinations (tenofovir/emtricitabine [TDF/FTC] and abacavir/lamivudine [ABC/3TC]) in virologically suppressed patients.

METHODS: BICOMBO is a multicentre trial comparing TDF/FTC-versus ABC/3TC-based regimens in patients with virological suppression. In a metabolic substudy, fasting total cholesterol (TC), very low density lipoprotein cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, LDL subfractions, apolipoprotein A-I (apo A-1), apolipoprotein B (apo B), triglycerides (TG), glucose, insulin, C-peptide and HOMA index were measured at baseline (BL) and 12 months. CV risk was estimated by the Framingham equation. Unpaired t-test or Mann-Whitney U test were used for comparisons between arms and paired t-test or Wilcoxon signed rank test were used for comparisons between BL and follow-up.

RESULTS: In total, 103 patients (TDF/FTC n=55 and ABC/3TC n=48) were evaluated. BL demographic and metabolic variables did not differ, except for insulin (TDF/ FTC 46.3 versus 61.1 pmol/l, P=0.06). At week 48, a significant increase in TC, LDL cholesterol and apo B, but also in HDL cholesterol and apo A-I was observed in ABC/3TC compared with TDF/FTC (P<0.001, P<0.001, P<0.006, P<0.001 and P<0.001, respectively). Despite these changes, LDL/HDL cholesterol and apo A-I/apo B ratios remained stable in both arms. An increase in small, dense LDL cholesterol subfractions (4, 5 and 6) was observed in both arms (ABC/3TC 36.8%, P<0.001; TDF/FTC 22.2%, P=0.004), but only ABC/3TC use was associated with an increase in the more atherogenic B phenotype (P=0.028) and a decrease in LDL cholesterol size (P=0.001). No significant changes were found in TG levels or estimated CV risk. Insulin levels increased (P=0.018) but HOMA index did not change in the TDF/FTC arm.

CONCLUSIONS: Quantitative lipid profile modifications were associated with the use of TDF/FTC and ABC/3TC. ABC/3TC was associated with a more atherogenic LDL cholesterol profile although estimated CV risk remained stable with both therapies.

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2008-11-06
O-08

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