Low bone mineral density in COPD patients with osteoporosis is related to low daily physical activity and high COPD assessment test scores

Figures & data

Table 1 Characteristics of the patients with COPD

Variables	Without OP (n=11)	OP (n=19)	P-value
Age	71.7±9.1	70.2±9.0	0.9370
Sex (n)
Male	10	18	0.6855
Female	1	1
Smoke status (n)
Never smoke	0	1	0.4603
Smoking	0	0
Ex-smoking	11	18
BMI, kg/m^2	27.7±4.2	23.5±3.9	0.0104
FFMI, kg/m^2	19.3±2.3	17.4±2.1	0.0328
CAT	5.0±3.8	8.1±5.8	0.0424
Pulmonary function test
FEV1a, %	42.6±15.8	44.3±14.2	0.758
FVC, %	67.0±14.5	64.1±14.0	0.5944
FEV1/FVC, %	50.6±10.5	49.2±12.1	0.7540
Bone mineral density
Lumbar spine, g/cm^2	1.05±0.05	0.86±0.04	0.0481
Total hip, g/cm^2	0.95±0.04	0.73±0.03	<0.0001
Femoral neck, g/cm^2	0.82±0.04	0.62±0.02	<0.0001

Notes: Values are expressed as the mean ± SD unless otherwise indicated;

a the prevalence on without OP group was 10% in stage GOLD I and II, 20% in stage GOLD III, and 6.7% in stage GOLD IV; prevalence of OP group was 23.3% in stage GOLD I and II, 30% in stage GOLD III, and 10% in stage GOLD IV; control vs COPD.

Abbreviations: BMI, body mass index; FFMI, fat-free mass index; CAT, COPD assessment test; FEV₁, forced expiratory volume in the 1 second; FVC, forced vital capacity; OP, osteoporosis; SD, standard deviation.

Figure 1 Comparison between OP and without OP.

Notes: (A) Daily physical activity, desaturation index, and low pulse oxygen saturation in COPD patients without and with OP; (B) serum TNF-α, IL-6, CRP, and 8-isoprostane levels in COPD patients without and with OP; *P<0.05; circles, without OP; squares, OP.
Abbreviations: OP, osteoporosis; cts·min⁻¹, counts per minute.

Table 2 Pearson’s correlation coefficients (r) of the bone mineral density, actigraphy activity, and CAT in the patients with COPD (n=30)

Indicators	BMD
	Lumbar spine	Total hip	Femoral neck
Age, years	0.011	0.028	0.123
BMI, kg/m^2	0.701**	0.761**	0.643**
FFMI, kg/m^2	0.666**	0.719**	0.628**
CAT, score	−0.147	−0.412*	−0.552**
FEV1, %	0.331	0.190	0.100
DPA, cts·min^−1	0.399*	0.602**	0.438*
DSI, %	0.000	−0.099	−0.150
Low SpO2 (%)	0.103	−0.032	−0.085

Notes:

* P<0.05;

** P<0.01.

Abbreviations: BMI, body mass index; FFMI, fat-free mass index; BMD, bone mineral density; FEV₁, forced expiratory volume in the 1 second; DPA, daily physical activity; DSI, desaturation index; CAT, COPD assessment test; cts·min⁻¹, counts per minute.

Figure 2 Pearson’s correlation scores of CAT and DPA assessments.

Notes: Correlation of (A) lumbar spine, total hip, and femoral neck T-scores and DPA, and (B) lumbar spine, total hip, and femoral neck T-scores and CAT scores in COPD patients.
Abbreviations: CAT, COPD assessment test; DPA, daily physical activity; cts·min⁻¹, counts per minute.

Table 3 Linear regression analysis of bone mineral density in the patients with COPD (N=30)

Variables	Lumbar spine BMD			Total hip BMD			Femoral neck BMD
	β	t	P-value	β	t	P-value	β	t	P-value
Age, years	−0.050	−0.310	0.759	−0.006	−0.044	0.966	0.131	0.878	0.396
FEV1, %	0.121	0.734	0.471	−0.074	−0.539	0.596	−0.177	−1.166	0.259
BMI, kg/m^2	0.595	1.379	0.182	0.744	2.083	0.050	0.327	0.823	0.420
FFMI, kg/m^2	0.100	0.222	0.826	−0.153	−0.409	0.688	0.247	0.595	0.558
CAT score	0.116	0.689	0.498	−0.121	−0.872	0.393	−0.384	−2.486	0.021
DPA, cts·min^−1	0.059	0.299	0.768	0.191	1.168	0.256	−0.058	−0.320	0.752

Notes: Lumbar spine BMD: adjust R²=0.360, F=3.247, P=0.017. Total hip BMD: adjust R²=0.561, F=6.112, P=0.001. Femoral neck BMD: adjust R²=0.457, F=4.366, P=0.004.

Abbreviations: BMD, bone mineral density; FEV₁, forced expiratory volume in 1 second; BMI, body mass index; FFMI, fat-free mass index; CAT, COPD assessment test; DPA, daily physical activity.