A Study On The Measurement Of Bone Mineral Density And Trabecular Bone Fraction In HIV-infected Patients

Part 1 Bone Mineral Density and Trabecular Bone Score Changes in Chinese Antiretroviral-Treated HIV-Infected IndividualsObjectives HIV infection and antiretroviral therapy(ART)have been associated with bone damage.This study aims to evaluate changes in bone mineral density(BMD)and a novel index that estimates bone microarchitecture named trabecular bone score(TBS),among Chinese persons living with HIV(PLWH)treated with ART.Methods A retrospective chart review of adult PLWH at the Infectious Diseases Department were conducted.Patients who had a DXA scan prior to ART and at least one follow-up DXA after ART initiation were included.Baseline and follow-up BMD and TBS data of included patients were collected,and factors associated changes in BMD and TBS after 48 weeks ART were analyzed.Results Totally 459 PLWH were included.The mean age was 36.1±11.3 years.There were 421 males(91.7%).Among 391 patients(85.2%)who were under 50 years,40 patients(10.2%)had BMD within the expected range for age but partially degraded TBS or degraded TBS.Among 68 patients?50 years,13 patients(19.1%)had a normal BMD but partially degraded or degraded TBS.There was no statistically significant difference between the mean percent decrease in lumbar spine(LS)BMD at the 48 weeks and 96 weeks(-3.0%vs.-2.4%,p=0.196),followed by an increase in the 144 weeks(-1.1%).Then the mean percent decreases in LS BMD remained stable at 144 and 192 weeks.The BMD of the femoral neck(FN)decreased by 3.5%in 48 weeks and 4.6%in 96 weeks.Then the percent change in the FN BMD remained stable.The BMD of the total hip(TH)decreased by 3.2%in 48 weeks and 4.2%in 96 weeks.The change trend of TH BMD and FN BMD was similar.TBS decreased by 1.6%in 48 weeks and then remained stable.Greater change in TBS over one year was associated with lower BMI and lower baseline CD4+cell count.TDF and LPV/r-containing regimens were associated with greater declines in BMD at each site.But unlike BMD measures,TBS was not correlated with treatment with TDF or LPV/r in our study population.Conclusions This is the first study among Chinese PLWH to evaluate the impact of ART on BMD and TBS.At baseline,approximately 20%of patients who were?50 years had normal BMD,but impaired bone microstructure based upon TBS.For patients with 240 weeks(5 years)of exposure to ART,there is a stabilization of BMD and TBS after initial nadir.However,FN BMD,TH BMD and TBS remained low at 5 years relative to baseline.Part 2 Changes in Bone Mineral Density and Trabecular Bone Score in Chinese HIV-Infected Patients after Switching to TDF-based Antiretroviral TherapyObjectives Although tenofovir disoproxil fumarate(TDF)is highly effective against HIV,it has been associated with bone damage.Previous studies have shown declines in bone mineral density(BMD)after TDF initiation and improves after discontinuing TDF.However,studies evaluating skeletal changes after switching to TDF have been lacking.The aim of this study is to explore the effects of TDF switch on BMD and trabecular bone score(TBS).Methods We performed a retrospective study of adult outpatients with HIV seen at a large tertiary care hospital.Patients were included if they had a DXA scan prior to ART initiation,and were:(1)consistently treated with non-TDF-based ART and had a DXA scan after at least 96 weeks of treatment(non-TDF group),or(2)consistently treated with non-TDF-based ART for at least 48 weeks,then switched from non-TDF-based to TDF-based ART,and had a DXA scan at the time of switch and at least 48 weeks after TDF switch(TDF group).Demographic and clinical history,HIV history,BMD and TBS data were collected.Associations between risk factors and changes in BMD and TBS were analyzed using linear regression.Results Forty-three patients whose regimens switched from non-TDF-based to TDF-based ART(TDF group),and 50 patients who received continuous non-TDF-based ART(non-TDF group)were included.The mean age of the two groups was similar(36.9±10.1yrs vs.38.9±14.1yrs,p=0.483),as was the mean time from baseline to the last visit(7.0±2.8yrs vs.6.4±3.1yrs,p=0.296).In the TDF group,the mean time from baseline to switch point was 3.5±2.0yrs,and from the switch to the last follow-up was 3.5±2.2 yrs(p=0.515).BMD of total hip and femoral neck,and TBS decreased significantly from baseline to the last clinic visit within both groups.However,between the two groups,only changes in total hip BMD differed from baseline to the last follow-up point(-5.5±5.5%vs.-3.2±4.5%,p=0.031).In the multivariable linear regression analysis,switch to TDF had no association with changes in BMD or TBS.Conclusions After switch to TDF-containing ART,more BMD loss was observed only at total hip and no impact on bone microstructure,as measured by TBS,was observed.Switch to TDF had no association with ch anges in BMD or TBS.Part 3 Lumbar Vertebrae Morphological Analysis and an Additional Approach for Vertebrae Identification in Lumbar Spine DXA ImagesObjectives Dual-energy X-ray absorptiometry(DXA)is the generally accepted approach to diagnose osteoporosis.Lumbar spine is one of the most common regions of interest.Accurate identification of lumbar vertebrae plays an important role in DXA measurement.Moreover,lumbar spine DXA image is the basis to calculate trabecular bone score(TBS).So the quality of DXA analysis can influence the diagnosis and treatment of osteoporosis and the calculation of TBS.The aims of this study are to analyze the morphological characteristics of lumbar vertebrae,compare of several common lumbar vertebrae identifying methods in lumbar spine DXA images and present an additional simple strategy for identifying L5 named the "—"-shaped L5.Methods Lumbar spine DXA images from adult patients receiving care at a large tertiary hospital were retrospectively reviewed.For each patient,data were collected regarding key anatomic features seen on DXA:(1)the lowest vertebra with ribs;(2)positions of the longest transverse process;(3)positions of the most superior portions of the iliac crests;(4)the proportion of patients presenting with "H"-shaped L4;(5)the changes of the angles at the vertex of the two virtual lines connecting the central spinal process with the bilateral pedicles from L1 to L5.Record the proportion of patients presenting with"—"-shaped L5.Chi-squared analyses were used to compare proportions of patients presenting with "H"-shaped L4 and "—"-shaped L5 across age strata.Results DXA images from 1125 patients(79.6%female)were evaluated.The mean age of patients was 52.5±14.8 years.The lowest ribs were most frequently(944 patients,83.9%)observed at T12.721(64.1%)individuals had the longest transverse processes at L3.A horizontal line drawn across the superior-most portions of the iliac crests crossed the disk space between L4 and L5 among 881(78.3%)patients.L4 was predominantly "H"-shaped(825 patients,73.3%),however we found that the proportion of individuals with "H"-shaped L4 decreased steadily after 50 year of age(?~2=34.027,p<0.001).By contrast we observed that L5 was predominantly "—"-shaped(903 patients,80.3%),with no significant differences in proportions across all age strata(?2=6.066,p=0.416).Statistically significant differences exist between the proportions of "H"-shaped L4 and proportions of "—"-shaped L5 in this study population(p<0.001).Conclusions We systematically evaluate anatomic features of lumbar spine DXA images and presents an additional method of DXA-based lumbar vertebrae identification,named the "—"-shaped L5.This approach was robust in our study population and stable across age strata,therefore addition of the "—"-shaped L5 approach to other approaches used in routine DXA analysis can potentially improve the accuracy of osteoporosis diagnosis.