Relationship of annual change in bone mineral density with extent of emphysematous lesions and pulmonary function in patients with COPD

Figures & data

Figure 1 Patient disposition and reasons for exclusion.

Figure 2 Images of thoracic vertebral bodies for measurement of computed tomography attenuation.

Notes: (A) Sagittal image of thoracic vertebral bodies. (B) Images of identified thoracic vertebral bodies. Each vertebrae was automatically identified and painted using different colors.

Table 1 Patient characteristics (N=103)

Characteristic
Age (years)	69.8±7.8
Gender (female/male)	7/96
Current smoking status at enrolment	26 (25.2)
Smoking history (pack-years)	61.4±27.8
Follow-up period (years) (1/2/3/4)	9/15/50/29
BMI (kg/m^2)	22.7±3.0 (n=100)
MRC dyspnea score (0/1/2/3/4/5)	8/12/37/44/1/1
SGRQ activity score	41.4±22.4
Osteoporosis medication
Vitamin D	2 (1.9)
Laboratory tests
White blood cell count (cells/m^2)	6,505±1,674
Neutrophil count (cells/m^2)	3,804±1,378
Eosinophil count (cells/m^2)	204±145
CRP (mg/dL)	0.34±0.43 (n=100)
IgE (IU/mL)	212.1±651.2 (n=88)
Lung function tests
FEV1.0 (L)	1.81±0.66
%FEV1.0	66.8±20.2
FEV1.0/FVC	0.52±0.12
GOLD stage (0/1/2/3/4)	7/25/48/21/2
LAV%	24.6±13.9 (n=102)
√Aaw at Pi10 (mm)	3.98±0.07 (n=94)
ABD4,7,10 (HU)	132.2±43.1
ABD1–12 (HU)	138.0±43.0
ΔABD4,7,10 (HU)	3.07±3.02
ΔABD1–12 (HU)	2.91±2.67
ΔFEV1.0 (mL)	23.0±22.0
ΔLAV%	0.69±0.46

Note: Data are expressed as mean ± SD or n (%).

Abbreviations: BMI, body mass index; MRC, Medical Research Council; SGRQ, St George’s Respiratory Questionnaire; CRP, C-reactive protein; IgE, immunoglobulin E; %FEV_1.0, percentage of FEV_1.0 predicted in accordance with the guidelines for pulmonary function tests issued by the Japanese Respiratory Society; GOLD, Global Initiative for Chronic Obstructive Lung Disease; LAV%, percentage of low attenuation volume; √Aaw at Pi10, square root of airway wall area of the hypothetical airway with an internal perimeter of 10 mm; ABD, average vertebral bone density; HU, Hounsfield unit; ABD_4,7,10, average bone densities of thoracic vertebrae 4, 7, and 10; ABD_1–12, average bone densities of all thoracic vertebrae; Δ, annual change in each variable.

Table 2 Association between ABD and other evaluated variables

Factor	ABD4,7,10		ABD1–12
	ρ	p-value	ρ	p-value
Age	−0.331	0.0006*	−0.317	0.0011*
BMI	0.246	0.0136*	0.236	0.0179*
Smoking history	−0.004	0.9718	0.029	0.7728
SGRQ activity score	−0.248	0.0115*	−0.261	0.0078*
White blood cell count	0.082	0.4117	0.089	0.3693
Neutrophil count	0.017	0.867	0.02	0.8452
Eosinophil count	0.229	0.0198*	0.234	0.0175*
Hb	0.132	0.1826	0.102	0.3034
CRP	−0.023	0.8209	−0.02	0.8455
IgE	0.019	0.8622	0.036	0.7361
FEV1.0 (L)	0.179	0.0713	0.168	0.0906
%FEV1.0	0.125	0.2092	0.112	0.2607
FEV1.0/FVC	0.17	0.0857	0.139	0.1626
FVC	0.129	0.1929	0.142	0.1517
LAV%	−0.372	0.0001*	−0.367	0.0001*
√Aaw at Pi10	0.099	0.345	0.103	0.3213
Annual change
ΔFEV1.0	0.12	0.2263	0.106	0.2866
ΔLAV%	0.08	0.4241	0.088	0.3788

Notes: Relationships were assessed by Spearman’s rank correlation test.

* Significant difference (p<0.05).

Abbreviations: ABD, average vertebral bone density; ABD_4,7,10, average bone densities of thoracic vertebrae 4, 7, and 10; ABD_1–12, average bone densities of all thoracic vertebrae; BMI, body mass index; SGRQ, St George’s Respiratory Questionnaire; Hb, hemoglobin; CRP, C-reactive protein; IgE, immunoglobulin E; %FEV_1.0, percentage of FEV_1.0 predicted in accordance with the guidelines for pulmonary function tests issued by the Japanese Respiratory Society; LAV%, percentage of low attenuation volume; √Aaw at Pi10, square root of airway wall area of the hypothetical airway with an internal perimeter of 10 mm; Δ, annual change in each variable.

Table 3 Relative contribution of each variable for prediction of ABD_4,7,10

Factor	t	p-value
LAV%	−0.48	0.6305
Age	−3.15	0.0022*
BMI	2.56	0.012*
SGRQ activity score	−0.67	0.504
Eosinophil count	1.18	0.2392

Notes: LAV%, age, BMI, SGRQ activity score, and eosinophil count were included as candidate-independent variables.

* Significant difference (p<0.05).

Abbreviations: ABD_4,7,10, average bone density of thoracic vertebrae 4, 7, and 10; LAV%, percentage of low attenuation volume; BMI, body mass index; SGRQ, St George’s Respiratory Questionnaire.

Table 4 Association between ΔABD and each variable

Factor	ΔABD4,7,10		ΔABD1–12
	ρ	p-value	ρ	p-value
Baseline
Age	0.094	0.345	0.092	0.3539
BMI	0.099	0.3269	0.155	0.1243
Pack-year	0.058	0.5606	0.038	0.7066
SGRQ activity score	−0.127	0.2015	−0.083	0.4022
White blood cell count	−0.054	0.5852	−0.009	0.9286
Neutrophil count	−0.099	0.3227	−0.069	0.488
Eosinophil count	0.053	0.5945	0.034	0.7365
Hemoglobin	0.133	0.1809	0.131	0.1864
CRP	0.031	0.7616	0.077	0.4469
IgE	0.037	0.7312	0.059	0.5838
FEV1.0	0.066	0.506	0.059	0.5567
%FEV1.0	0.024	0.8098	0.034	0.7355
FEV1.0/FVC	0.049	0.6267	0.058	0.5643
FVC	0.084	0.4008	0.042	0.6756
LAV%	−0.011	0.9107	−0.023	0.8218
√Aaw at Pi10	−0.032	0.763	−0.018	0.86
Annual change
ΔFEV1.0	0.092	0.3531	0.144	0.1482
ΔLAV%	−0.021	0.8339	−0.073	0.4616

Note: Relationships were assessed by Spearman’s rank correlation test.

Abbreviations: ABD, average vertebral bone density; ABD_4,7,10, average bone densities of thoracic vertebrae 4, 7, and 10; ABD_1–12, average bone densities of all thoracic vertebrae; BMI, body mass index; SGRQ, St George’s Respiratory Questionnaire; CRP, C-reactive protein; IgE, immunoglobulin E; %FEV_1.0, percentage of FEV_1.0 predicted in accordance with the guidelines for pulmonary function tests issued by the Japanese Respiratory Society; LAV%, percentage of low attenuation volume; Δ, annual change in each variable.