Background:  Low bone mass has been found in HIV-infected youths on HAART. However, the magnitude of this phenomenon and the role of HAART are not completely clarified. The use of tenofovir (TDF) in children has been associated to a reduction of bone mass measurements, but the results are controversial. We aimed to assess the long-term effect of an HAART regimen containing TDF on bone mass in HIV-infected youths.

Methods:  We studied 23 young HIV-infected patients (13 girls, age range at baseline 4.9 to 17.9 years) on successful HAART containing lamivudine (3TC) + stavudine (d4T) + 1 PI, who were switched to a 3TC/TDF/efavirenz (EFV) regimen. Bone mass measurements were obtained yearly for 48 months. We also measured bone mass in 194 healthy subjects (90 girls, age range 4.9 to 21.9 years). Bone mass was assessed by dual-energy X-ray absorptiometry (Prodigy, GE-Lunar, USA) at the lumbar spine and in the whole skeleton, and were expressed as bone mineral content. Polynomial regressions were computed to calculate bone mineral content expected values for healthy youths in both sexes. Differences between observed and expected values were calculated, and changes during the study were evaluated by analysis of variance (ANOVA) for repeated measures. Values are expressed as mean (SE).

Results:  At baseline the mean (SE) CD4 count was 869 (67), CD4 percentage was 34.9 (1.1), and HIV RNA was undetectable in all subjects. The 3TC/EFV/TDF regimen maintained a stable CD4⁺ count and retained a virologic control throughout the observation period. Lumbar spine bone mineral content measurements were lower than expected at baseline, and during follow-up. The mean difference was –3.3 (1.4) g at baseline and –2.9 (2.0) g at 48 months. ANOVA for repeated measures did not demonstrate significant changes over time (F = 0.19, p = 0.54). Similarly, the median difference between observed and expected whole skeleton bone mineral content values were –176 (68) g at baseline, and –201 (84) g at the end of the study. The changes over time were not significant (F = 0.60, p = 0.66).

Conclusions:  The results of the current study demonstrate that a HAART regimen containing TDF does not impair the bone mass accrual in children and adolescents. Nevertheless, despite the control of viral replication, such treatment does not restore bone mass values in subjects with low bone mineral content measurements.