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Maternal TDF Does Not Affect Infant Bone Mineral Content in Africa
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Conference on Retroviruses and Opportunistic Infections (CROI), February 22-25, 2016, Boston
Mark Mascolini
Unlike a US study, analysis of 362 infants born to HIV-positive African women starting antiretrovirals did not find that tenofovir disoproxil fumarate (TDF) affected bone mineral content (BMC) more than zidovudine in exposed infants [1].
The US PHACS study found that 74 HIV-uninfected infants born to HIV-positive mothers who took TDF during the third trimester had significantly lower whole-body BMC than 69 infants born to mothers who did not take TDF [2]. This difference persisted after statistical adjustment for factors that may affect BMC in infants. Both US and World Health Organization guidelines recommend TDF as a preferred antiretroviral for pregnant women.
Study P1084s set out to compare lumbar-spine and whole-body BMC at delivery in infants of African mothers randomized to begin one of three regimens in pregnancy: (1) zidovudine (plus single-dose nevirapine with a TDF/FTC tail), (2) zidovudine/lamivudine (ZDV/3TC) plus lopinavir/ritonavir (LPV/r), or (3) TDF/FTC plus LPV/r. To measure BMC, infants had DXA scans in the first 21 days of life.
In arms 1, 2, and 3, totals of 118, 129, and 115 infants received whole-body and/or lumbar-spine scans. Median maternal ages in the three arms were 25.5, 27, and 27 (P = 0.03). Median gestational age measured 40 weeks in arm 1, 39.7 weeks in arm 2, and 39 weeks in arm 3 (P = 0.14). Respective median birth weights were 3100 g, 2910 g, and 2920 g (P < 0.001). About half of the infants were girls. Overall median maternal CD4 count stood at 543, with little difference between the three groups.
Mean lumbar-spine BMC was lower in arm 2 (ZDV/3TC/LPV/r) than in the other two arms, but this mean did not quite differ significantly from means in arm 1 (P = 0.05) or arm 3 (P = 0.09), both of which contained TDF. In an analysis adjusted for baseline variables (country, maternal age, height), lumbar spine BMC was marginally lower in arm 2 (ZDV/3TC/LPV/r) than in arm 3 (TDF/FTC/LPV/r) (mean difference -0.07, P = 0.10). In an analysis adjusted for baseline variables plus at-DXA variables (infant age and length), that lower spine BMD in the ZDV/3TC/LPV/r arm became significant (mean difference -0.08, P = 0.04).
Mean whole-body BMC proved significantly lower in both triple-therapy arms (2 and 3) than in arm 1. But the difference between the TDF triple-therapy arm and the ZDV triple-therapy arm was not significant (P = 0.41). In an analysis adjusted for baseline and at-DXA variables, whole-body BMC did not differ significantly between the TDF triple-therapy arm and the ZDV triple-therapy arm, but the triple-therapy arms both had significantly lower whole-body BMD than arm 1.
The researchers noted that these findings may not apply to women with lower CD4 counts. They observed that the study population differed from the US PHACS population in that almost all women were black African, their CD4 counts were generally higher, and they had not taken antiretrovirals before pregnancy. The investigators cautioned that the clinical significance and persistence of these findings remain unknown. But the researchers are assessing lumbar-spine DXA findings in these infants at 6 months of age.
WEBCAST: http://www.croiwebcasts.org/console/player/29477?mediaType=audio&
References
1. Siberry GK, Tierney C, Stranix-Chibanda L, et al. Impact of maternal tenofovir use on HIV-exposed newborn bone mineral. Conference on Retroviruses and Opportunistic Infections (CROI), February 22-25, 2016, Boston. Abstract 36.
2. Siberry GK, Jacobson DL, Kalkwarf H, et al. Lower newborn bone mineral content associated with maternal use of tenofovir disoproxil fumarate. CROI 2014. Conference on Retroviruses and Opportunistic Infections. March 3-6, 2014. Boston. Abstract 71. http://www.natap.org/2014/CROI/croi_37.htm
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