CTNPT 001: Fracture case-control study in HIV

Objective

Gradual bone demineralization is a feature of normal aging: both men and women lose bone at a rate of .5% to 1% per year after age 35. However, studies show that people living with HIV experience accelerated losses of bone mineral density (BMD), particularly in the first year after starting antiretroviral therapy (ART). Measuring BMD is commonly used to assess risks of bone fractures and conditions such as osteoporosis (porous bone), a systemic skeletal disease characterized by low bone mass and loss of bone tissue. This pilot study compared bone architecture parameters (structure and strength) in adults living with HIV with and without a history of fracture. Although the traditional tool (dual-energy x-ray absorptiometry, or DXA) is helpful in assessing bone health, additional measurements may complement DXA in estimating fracture risk. Therefore, CNTPT 001 also looked at how clinically useful various new methods of assessing bone health may be in people living with HIV.

Study Population

The study included adults living with HIV who have had a fracture after their diagnosis and HIV-positive adults who have never had a fracture. The two groups were matched according to age, sex, smoking history, and race. In total, 23 pairs of participants were included in the study.

Study Approach

To see if there were any relevant differences between people living with HIV who have had a bone fracture and those who have not, numerous measurements were taken during study visits. These measurements included health history, HIV characteristics, physical characteristics, physical activity history, blood biochemistry, and multiple measurements related to bone health. These bone-specific measurements included DXA, trabecular bone score (TBS), hip structural analyses (HSA), vertebral fracture assessment (VFA), and high-resolution peripheral quantitative tomography (HR-pQCT).
This study was intended to inform the design of a future intervention trial aimed at reversing the accelerated loss in bone strength seen during the first year of ART.

Results

In general, this study found a trend towards lower bone density, health, and strength in people with a history of fracture. Because this was a pilot study, only a small number of participant pairs were used. For this reason, the study investigators are unable to confidently say which tool is best for measuring bone health in people living with HIV. However, this study helps in the design of future research because it has identified potential tools that may be useful as a part of a testing protocol as well as areas of the bone that may be of particular importance to bone loss in people living with HIV. This research will also help with future study because it suggests the number of participants needed for a larger study and the challenges of recruitment.

Conclusions

This is the first study to compare bone strength and structure between people living with HIV in relation to fracture history. CTNPT 001 suggests that there may be difference in bone structure, health, and function between these groups. This small study also suggests that new techniques used to assess bone characteristics may be useful as a part of a comprehensive assessment in a larger trial. As a pilot trial, CTNPT 001 provided important preliminary information that will help in the statistical planning of future studies.