Conversion of osteoporotic-like vertebral fracture severity score to osteoporosis T-score equivalent status: A framework study for older Chinese men

Abstract

Objectives: To define what portion of older community men with what severity of radiographic osteoporotic-like vertebral fracture (OLVF) correspond to what low T-score status.

Methods: There were 755 community Chinese men (age: 76.4 ± 6.7 years) with thoracic and lumbar spine radiographs, and hip and lumbar spine bone mineral density measures. For each vertebra in a subject, a score of 0, -0.5, -1, -1.5, -2, -2.5, and -3 was assigned for no OLVF or OLVF of <20%, ≥ 20-25%, ≥ 2 5%-1/3, ≥ 1/3-40%, ≥ 40%-2/3, and ≥ 2/3 vertebral height loss, respectively. OLVFss was defined as the summed score of vertebrae T4 to L5. OLVFss and T-scores were ranked from the smallest to the largest values.

Results: OLVFss of -2, -2.5, -3, corresponded to a mean femoral neck T-score of -2.297 (range: -2.355∼-2.247), -2.494 (range: -2.637∼ -2.363), and -2.773 (range: -2.898∼-2.643), a mean hip T-score of-2.311 (range: -2.420∼-2.234), -2.572 (range: -2.708∼-2.432), -2.911 (range: -3.134∼-2.708), a mean lumbar spine T-score of -2.495 (range: -2.656∼-2.403), -2.931 (range: -3.255∼-2.664), and -3.369 (range: -3.525∼-3.258). The Pearson correlation value of OLVFss and T-score of femoral neck, hip and lumbar spine was r = 0.21, 0.26, and 0.22 (all P < 0.0001).

Conclusions: A single severe grade radiological OLVF (≥ 40% height loss) or OLVFss ≤ -2.5 suggest the subject is osteoporotic, and a single collapse grade (≥ 2/3 height loss) OLVF or OLVFss ≤ -3 meets osteoporosis diagnosis criterion. The results highlight the difficulty of diagnosing osteoporotic vertebral fractures among Chinese older men.

Keywords: Bone mineral density; Osteoporosis; Osteoporotic vertebral fracture; Spine; T-score.

Fig-1

Ranked OLVF sum score (OLVFss) and T-score of the combined subgroup-A and subgroup-B subjects with those of OLVFs = 0 not presented. Dotted blue lines indicate conventional cutpoint T-score of −2.5. Yellow lines indicate T-score of −2.7 (A),-2.6 (B) and −3.2 (C), which are also the intersections (the cross points of the yellow lines and red lines) with lowest T-score value corresponding to OLVFss −2.5 and highest T-score value corresponding to OLVFss −3.0. A: OLVFss and femoral neck T-score; B: OLVFss and total hip T-score; C: OLVFss and lumbar spine T-score. OLVF: osteoporotic-like vertebral fracture.

Fig-2

Correlations between OLVF sum score (OLVFss, X-axis) and T-score (Y-axis. A: femoral neck; B: total hip; C: lumbar spine). Dotted blue lines indicate conventional cutpoint T-score of −2.5. Dotted orange lines indicate OLVFss of −2.5. Red lines indicate linear fit of OLVFss and T-scores. OLVF: osteoporotic-like vertebral fracture.

Fig-3

Chest radiograph vertebral deformity index (VDI) among young and middle-aged male patients (N = 374) unrelated to spine disorders. It can be assumed that for Chinese men younger than 60 years old there would be few cases, or none, had osteoporosis. One fracture shaped vertebral deformity (FSVD) of ‘minimal’, ‘mild’, ‘moderate’, ‘moderately-severe’, ‘severe’, ‘collapsed’ has < 20%, ≥ 20–25%, ≥ 25%–1/3, ≥ 1/3–40%, ≥ 40%–2/3, and ≥ 2/3 vertebral height loss, and is assigned a score of −0.5, −1.0, −1.5, −2.0, −2.5, −3 respectively. Chest VDI is calculated by summing the scores of all vertebrae (T4 to L1 or L2). Patients with any FSVD are presented. For the subjects included, it was estimated that 26.4% of the cases age > 20 years had a history of being a farmer or physical laborer, and for cases aged > 45 years and > 60 years, 36.1% and 42.8% respectively had a history of being a farmer or physical laborer. Adapted from Ma and Wang [24] with permission.

Fig-4

Relationship between 8 bands of mean OLVFss and the corresponding femoral neck T-score (T-score neck, men's data derived from Table 2). A: Year-14 subjects (mean age: 82.8 years) were older than the year-0 subjects (mean age: 73.0 years), and the femoral neck T-scores were lower for the year-14 subjects when OLVFss was 0, -0.5, and −1. However, after OLVFss was ≤ −2.5, the femoral neck T-scores were lower for the year-0 subjects. This means, for subjects of relatively younger age, statistically an even lower BMD is required for the subjects to sustain an OVF. This phenomenon suggests the OLVFss of −2.5, −3.0, and ≤ 3.5 show densitometrical osteoporotic features (arrows). B: Women's data from reference 11 (year-0 and year-4 subjects mean age: 73.6 years, year-14 subjects: 82.2 years). OLVFss of −1, −1.5, −2, −2.5, −3.0, and ≤ 3.5 show densitometrical osteoporotic features (arrows). It was concluded that statistically OVFss ≤ −1 suggests a female subject is osteoporotic, while OVFss ≤ −1.5 qualifies osteoporosis diagnosis. OLVFss: osteoporotic-like vertebral fracture sum score; OVF: osteoporotic vertebral fracture.