Quantitative CT lumbar spine BMD cutpoint value for classifying osteoporosis among older Chinese men can be the same as that of older Chinese women, both much lower than the value for Caucasians

Abstract

For older Caucasian women and men, the QCT (quantitative CT) lumbar spine (LS) bone mineral density (BMD) threshold for classifying osteoporosis is 80 mg/ml. It was recently proposed that, for older East Asian women, the QCT LS BMD value equivalent to the Caucasian women's threshold of 80 mg/mL is about 45∼50 mg/ml. For a data of 328 cases of Chinese men (age: 73.6 ± 4.4 years) who had QCT LS BMD and DXA LS BMD at the same time and with the DXA BMD value of ≤ 0.613 g/cm² to classify osteoporosis, the corresponding QCT LS BMD threshold is 53 mg/ml. Osteoporotic-like vertebral fracture sum score (OLVFss) ≤ -2.5 has been proposed to diagnose osteoporosis. For 316 cases of Chinese men (age:73.7±4.5 years), OLVFss ≤ -2.5 defines an osteoporosis prevalence of 4.4%; to achieve this osteoporosis prevalence, the corresponding QCT LS BMD value is < 47.5 mg/ml. In the China Action on Spine and Hip Status study, a Genant grades 2/3 radiographic 'osteoporotic vertebral fracture' prevalence was 2.84% for Chinese men (total n = 1267, age: 62.77 ± 9.20 years); to achieve this osteoporosis prevalence, the corresponding BMD value was < 42.5 mg/ml. In a study of 357 Beijing older men, according to the clinical fragility fracture prevalence and femoral neck DXA T-score, the QCT LS BMD value to classify osteoporosis was between 39.45 mg/ml and 51.38 mg/ml. For older Chinese men (≥ 50 years), we recommend the cutpoint for the QCT LS BMD definition of osteoporosis to be 45∼50 mg/ml which is the same as the value for Chinese women.

Keywords: Bone mineral density (BMD); Chinese men; Osteoporosis; Quantitative CT; lumbar spine.

Fig. 1

Lower hip fragility fracture (FF) in Asian men relative to Caucasian men (A, B), lower clinical vertebral FF in men relative to women (C), and lower clinical vertebral FF in East Asian men relative to Caucasian men (D). A: Hip Fracture Rates in Hong Kong and the United States, 1988 through 1989. Data re-plotted from [17]. B: Age-standardized hip fracture incidence in men from 2002 to 2008 for US Medicare beneficiaries (≥ 65 years old). Data re-plotted from Wright et al. J Bone Miner Res 2012;27:2325–32. Data in (C) and (D) are from ‘Osteoporosis Fracture in Men (Hong Kong)’ study, ‘Osteoporosis Fracture in Women (Hong Kong)’ study, Freitas et al. Osteoporos Int 2008;19:615–23 (MrOS USA study), Sanders et al. Osteoporos Int 1999;10:240–7 (Geelong study), and Cooper et al. J Bone Miner Res 1992;7:221–7 (Rochester study), Sakuma et al., J Bone Miner Metab 2008;26:373–8 (Japan Sado 2004), Imai et al., J Bone Miner Metab 2019;37:484–90 (Japan Sado 2015)

Fig. 2

Correlation analyses of LS (lumbar spine) BMD measured by QCT and LS BMD measured by DXA. A: 328 Chinese men (age: 73.6 ± 4.4 years) who had QCT LS (L1 and L2) BMD and DXA LS BMD at the same time. The data are from Osteoporotic Fracture in Men (MrOS) Hong Kong year-2 follow-up study. The DXA BMD cutpoint value to define osteoporosis is 0.613 g/cm² (Hologic densitometer) [10], and the corresponding QCT BMD is 53 mg/ml. For QCT value of 50 mg/ml, the corresponding DXA BMD value is 0.594 g/cm². B: Results of mixed-sex 48 primary hyperparathyroidism patients (age: 53.77 ± 11.04 years) reported by Chen et al. [20]. The blue dotted crosses show the relationship between DXA measure and QCT measure in (B) is approximately similar to that in (A)

Fig. 3

Percentage of osteoporosis defined by OLVFss (osteoporotic-like vertebral fracture sum score) and QCT LS (lumbar spine L1 and L2) BMD. OLVFss ≤ -3, ≤ -2.5, ≤ -2.0, ≤ -1.5, ≤ -1.0, ≤ -0.5 defines 2.52%, 4.43%, 6.01%, 12.65%, 17.41%, and 35.44% of the study subjects (n = 316, mean age: 73.7 years) being osteoporotic, respectively. The recommended OLVFss for defining osteoporosis is ≤ -2.5 [24], and this defines osteoporosis prevalence being 4.43% for this sample. QCT LS BMD of 47.5 mg/ml, 50 mg/ml, 80 mg/ml defines 4.43%, 5.06%, and 31.32% of the subjects being osteoporotic, respectively. Data are from MrOS(Hong Kong) study for Chinese men (Table 1)