A Study About Switching From TDF to TAF
Focus on Lipids (Cholesterol and Triglycerides)
In general, when researchers assessed blood samples that were taken when participants had been fasting, they found that, over time, there were modest elevations in lipid levels among TAF users compared to TDF users. The lipids assessed included the following:
However, the ratio of total cholesterol to HDL-C was similar in TAF and TDF users, suggesting that their future risk for cardiovascular disease was more or less the same in people who received TAF or TDF.
The distribution of participants who initiated lipid-lowering therapy during the study was as follows:
Comparing Changes in Bone Density
Overall, a statistically significant increase in bone density (2%) occurred among TAF users. In contrast, participants who remained on TDF had their bone density decrease slightly.
Changes in Osteoporosis Status
Bone thinness can be grouped into two categories -- osteopenia, a mild form of decreased bone density, and osteoporosis, a severe form of bone density loss.
Looking at the Spine
At the start of the study, osteopenia and osteoporosis were distributed among participants as follows:
After 48 weeks, the distribution of these conditions in the spine was as follows:
Looking at the Hips
When researchers assessed bone density in the hips, the distribution of osteopenia and osteoporosis at the start of the study was as follows:
After 48 weeks, the distribution of osteoporosis and osteopenia in the hips was as follows:
Research has found that the original formulation of tenofovir (TDF) can, in some users, cause varying degrees of kidney injury. Therefore, in clinical trials of TDF (and its successor compound, TAF) it is important to conduct detailed and complex assessments of kidney health.
In the present study, in general, participants taking TDF-based regimens were more likely to develop signals of kidney injury than participants on TAF-based regimens.
Researchers assessed certain proteins in the urine as follows:
Note: Some of the tests above, particularly concerning retinol-binding protein and beta2-microglobulin, are usually only done as part of research, not routine care in the clinic.
While participants were on a TAF-based regimen, levels of the four proteins in the urine fell, suggesting improved kidney health in participants. Another measure of kidney health, eGFR (estimated glomerular filtration rate), improved very modestly in TAF users. In contrast, changes to the urinary proteins among participants on a TDF-based regimen were unfavourable.
Switching from a TDF-based regimen to a TAF-based regimen appears to be safer for kidney and bones.
TAF appears to be equivalent to TDF when used as part of combination anti-HIV therapy.
Mils A, Andrade-Villanueva J, DiPerri G, et al. Switching from a tenofovir disoproxil fumarate (TDF)-based regimen to a tenofovir alafenamide (TAF)-based regimen: data in virologically suppressed adults through week 48 of treatment. In: Program and abstracts of the 8th IAS Conference on HIV Pathogenesis, Treatment and Prevention, 19-22 July 2015, Vancouver, Canada. Abstract TUAB0102.
This article was provided by Canadian AIDS Treatment Information Exchange. It is a part of the publication TreatmentUpdate. Visit CATIE's Web site to find out more about their activities, publications and services.
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