The Suitable Population for Opportunistic Low Bone Mineral Density Screening Using Computed Tomography

Figures & data

Figure 1 Flow diagram for screening patients.

Figure 2 The 7th thoracic vertebra was located and the CT value of mid-sagittal plane was measured in the region of interest (ROI).

Table 1 Baseline Characteristics

Characteristics	Normal (n=353)	Low-BMD (n=915)	P
Sex, n (%)			< 0.001
Male	219 (62.0)	367 (40.1)
Female	134 (38.0)	548 (58.9)
Age, mean ± SD, years	57.16±11.85	62.88±11.02	< 0.001
Age, n (%)			< 0.001
<50	86 (24.4)	100 (10.9)
50–59	116 (32.9)	247 (27.0)
60–69	99 (28.0)	321 (35.1)
≥70	52 (14.7)	247 (27.0)
Height, mean ± SD, cm	166.62 ± 8.30	157.92 ± 8.62	< 0.001
Height, n (%)			< 0.001
≤150	18 (5.1)	173 (18.9)
151–160	102 (28.9)	390 (42.6)
161–170	151 (42.8)	276 (30.2)
>170	82 (23.2)	76 (8.3)
Weight, mean ± SD, kg	69.63 ± 12.00	60.13 ± 10.83	< 0.001
Weight, n (%)			< 0.001
≤50	11 (3.1)	183 (20.0)
51–60	71 (20.1)	300 (32.8)
61–70	113 (32.0)	292 (31.9)
>70	158 (44.8)	140 (15.3)
T-score, mean ± SD	−0.13±0.66	−2.42±0.93	< 0.001
CT-T7, mean ± SD, HU	196.18 ± 44.05	135.40 ± 44.11	< 0.001

Abbreviations: SD standard deviation; CT-T7, seventh thoracic CT; HU, Hounsfield unit; Low-BMD (osteopenia + osteoporosis).

Figure 3 Scatter plot of the distribution of CT values and T-score. (a–d) show the different groups by sex, age height, and weight, respectively.

Table 2 Multivariate Logistic Regression Analysis

Variable	OR	95% CI	P value
Sex, female	1.420	0.953–2.117	0.085
Age, ≥ 70 years	1.484	0.981–2.246	0.062
Height, >160cm	0.508	0.340–0.759	0.001
Weight, >60 kg	0.403	0.290–0.561	<0.001
CT-T7, >150 HU	0.089	0.059–0.133	<0.001

Abbreviations: CT-T7, seventh thoracic CT; HU, Hounsfield unit; OR, odds ratio; CI, confidence intervals.

Table 3 The Performance of Predicting Low Bone Mineral Density Using Receiver Operating Characteristic (ROC) Curves Analysis

Variable	AUC (95% CI)	High Sensitivity (Approximately 90%)			High Specificity (Approximately 90%)			Youden’s Index
		Threshold	SE (%)	SP (%)	Threshold	SE (%)	SP (%)
Gender
Male	0.744 (0.703–0.785)	202.82	90%	39.7%	141.95	36.5%	90%	0.355
Female	0.894 (0.866–0.921)	176.81	90%	67.9%	140.25	69.3%	90%	0.615
Age, years
<50	0.747 (0.676–0.818)	233.68	90%	36.0%	167.66	29.0%	90%	0.433
50–59	0.809 (0.762–0.857)	201.61	90%	52.5%	150.71	44.8%	90%	0.479
60–69	0.822 (0.777–0.867)	172.55	90%	52.6%	130.76	50.6%	90%	0.486
≥70	0.914 (0.877–0.950)	145.69	90%	73.1%	126.31	76.1%	90%	0.691
Height, cm
≤150	0.938 (0.899–0.977)	166.21	90%	77.8%	159.59	86.7%	90%	0.805
151–160	0.867 (0.830–0.904)	190.80	90%	61.8%	140.63	60.8%	90%	0.580
161–170	0.772 (0.725–0.818)	196.66	90%	47.7%	142.86	40.6%	90%	0.439
>170	0.722 (0.645–0.845)	196.65	90%	42.7%	140.36	36.8%	90%	0.345
Weight, kg
≤50	0.943 (0.903–0.983)	179.32	90%	81.8%	172.61	87.4%	90%	0.825
51–60	0.900 (0.865–0.936)	189.97	90%	71.8%	149.64	67.7%	90%	0.652
61–70	0.791 (0.743–0.838)	194.64	90%	48.7%	139.68	48.3%	90%	0.431
>70	0.769 (0.716–0.821)	192.73	90%	44.3%	140.62	45.0%	90%	0.400

Abbreviations: AUC, area under the curve; CI, confidence intervals; SE, sensitivity; SP, specificity.

Figure 4 The receiver operating curve (ROC) curves of CT values in the diagnostic efficacy of low-BMD. (a–d) show the different groups by sex, age height, and weight, respectively.