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

LONG-TERM CHANGES IN BODY FAT AND BONE MASS DENSITY AFTER SWITCHING FROM NUCLEOSIDE REVERSE TRANSCRIPTASE INHIBITORS TO FIXED-DOSE TENOFOVIR/EMTRICITABINE OR ABACAVIR/LAMIVUDINE

Antiviral Therapy 2008; 13(Suppl. 4):A35 (abstract no. P-17)

A Curran¹, P Barragan², M Loncà³, M Crespo¹, E Martinez³, M Piron¹, E Ferrer², D Podzamczer², JM Gatell³ and E Ribera^1
1Hospital Universitari Vall d’Hebron, Barcelona, Spain; ²Hospital Universitari de Bellvitge, Barcelona, Spain; ³Hospital Clínic, Barcelona, Spain

BACKGROUND: Whether switching to fixed-dose tenofovir/ emtricitabine (TE) or abacavir/lamivudine (AL) has a different impact on body fat and bone mineral density (BMD) is unknown. The BICOMBO study randomized patients to switch their nucleoside reverse transcriptase inhibitors (NRTI) to TE or AL.

METHODS: Participants at three sites were co-enrolled in the BICOMBO Body Composition substudy. Dual-energy X-ray absorptiometry scans were performed at baseline and annually. Regional fat and BMD changes from baseline in both groups were compared with non-parametrical tests. Changes in limb and total fat were assessed both as absolute and percent changes relative to baseline. The sample size was calculated to detect an increase in limb fat of 500 g from baseline with 80% power at a 5% significance level.

RESULTS: There were 45 patients (median 42 years, 73% male, 11% on protease inhibitor and 89% on non-nucleoside reverse transcriptase inhibitor) randomized to TE (n=25) or AL (n=20). Previous antiretroviral regimens and baseline characteristics were equivalent between groups. At baseline, limb and total fat (median, interquartile range) in the pooled group was 5,082 g (3,386–6,434 g) and 14,619 g (10,498–19,071 g), respectively. There was an absolute gain of fat and BMD in both groups. Limb fat gain at 96 weeks was 337 g (7.6%, P=0.397 within group) in the TE group and 756 g (12.1%, P=0.023 within group) in the AL group (P=0.126 between groups). Total fat changes at 96 weeks were a decrease of 130 g (0.69%, P=0.757 within group) in the TE group and an increase of 1,779 g (12.1%, P=0.044 within group) in the AL group (P=0.087 between groups). BMD increased from 0.93 to 1.14 g/cm² (P<0.001 within group) in the TE group and from 1.06 to 1.18 g/cm² (P=0.001 within group) in the AL group (P=0.217 between groups). Patients on thymidine analogues-containing therapy at baseline (n=18) experienced higher increments in limb fat than those not (n=27) – absolute change 587 versus 205 g (P=0.039) and percent change relative to baseline 14.5% versus 3.7% (P=0.044).

CONCLUSIONS: After 96 weeks of follow-up, switching from NRTI to either TE or AL similarly increased limb fat and BMD.

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2008-11-06
P-17

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