The Impact Of Age At Attainment Of Peak Bone Mineral Density On T-scores For Diagnosing Osteoporosis And Low Bone Mass

Objectives:Osteoporosis is a major public health problem worldwide.Lower peak bone mineral density(BMD)in youth may be the single most important factor leading to the development of osteoporosis in the elderly.However,age at attainment of peak BMD is still unclear.BMD T-score reference may be updated when the peak BMD of the population is unclear and may need to be updated.Therefore,the study purpose was to estimate age at attainment of peak BMD in both sexes at the femoral neck,total hip and lumbar spine using the most recent NHANES data.Our second objective was to update BMD T-score references using the peak BMD and to compare the means(SDs)between the existing and updated BMD T-score references from non-Hispanic white females.Methods:Using cross-sectional data from the National Health and Nutrition Examination Survey(NHANES)2005-2014,we included 18,713 individuals with complete and valid data on femoral neck,total hip and lumbar spine BMD.Generalized additive models were used to estimate the age at attainment of peak BMD and 95%confidence intervals(95%Cls).We compared the means(SDs)between the existing and updated BMD T-score references from non-Hispanic white females.BMD data within the age at attainment of peak BMD±5 years were used to calculate updated BMD T-score references.The prevalence of individuals with osteoporosis and low bone mass defined using the different BMD T-score references were compared using multivariable logistic regression models.Model covariates were sex,age,body mass index(BMI)and race.Results:1.A total of 18,713 participants were analyzed in this study.The cohort’s average age were 34.0 years and 37.0 years for males and females,respectively and there were approximately equal percentages of males and females represented in the study cohort(51.1%vs 48.9%).More females than males were overweight.2.The relationships of age with femoral neck BMD and total hip BMD generally followed a left skewed―bell‖shape in both sexes.Age at attainment of peak femoral neck,total hip and lumbar spine BMD were 20.5 years,21.2 years and 23.6years in males,and 18.7 years,19.0 years and 36.1 years,respectively in females.3.When subgroup analysis was performed by race,in males,age at attainment of peak BMD was reached later in Hispanic and non-Hispanic blacks than in non-Hispanic whites and Mexican Americans at the femoral neck,total hip and lumbar spine sites.Hispanics reached peak BMD at the latest age,and non-Hispanic whites reached peak BMD at the earliest age;in females,we found non-Hispanic blacks and non-Hispanic whites reached peak BMD at a later age than Mexican Americans and Hispanics at three skeletal sites,and Hispanics reached peak BMD at the earliest age.When subgroup analysis was performed by BMI,BMI≥30 reached peak BMD earlier than BMI<30 for different skeletal sites,regardless of male and female.Race and BMI were not associated with the age at attainment of peak BMD(all P>0.05).4.Based on the age at attainments of peak BMD,we determined that the updated averages of BMD(SDs)for diagnosing osteoporosis at the femoral neck,total hip,and lumbar spine were 0.888 g/cm~2(0.121 g/cm~2),0.963 g/cm~2(0.119 g/cm~2),and1.065 g/cm~2(0.122 g/cm~2).5.The updated averages of BMD(SDs)for diagnosing osteoporosis at femoral neck and total hip were higher than that under the existing reference(existing reference values for:femoral neck BMD mean[SD]=0.858 g/cm~2[0.120 g/cm~2],P<0.01,total hip BMD mean[SD]=0.942 g/cm~2[0.122 g/cm~2],P<0.01,lumbar spine BMD mean[SD]=1.040 g/cm~2[0.110 g/cm~2].6.In males,the prevalence of osteoporosis at the femoral neck and total hip using the updated BMD T-score references were significantly higher than the prevalence of these conditions using the existing references(P<0.001).The prevalence of individuals with osteoporosis at the lumbar spine using the updated BMD T-score reference was significantly lower than that using the existing reference.Similar patterns were noted in females(P<0.001).7.The prevalence of low bone mass at the femoral neck,total hip and lumbar spine defined using the updated references in males and females were higher than that defined using the existing references(P<0.001).Conclusion:1.Age at attainment of peak femoral neck,total hip and lumbar spine BMD were 20.5 years,21.2 years and 23.6 years in males,and 18.7 years,19.0 years and36.1 years in females,respectively.2.Age at attainment of peak BMD varied by skeletal sites and sex.3.Race and BMI were not associated with the age at attainment of peak BMD.4.The updated averages of BMD(SDs)for diagnosing osteoporosis at femoral neck and total hip were higher than that under the existing reference.5.We found significant differences in the prevalence of individuals classified as having osteoporosis and low bone mass between the updated and existing BMD T-score references.