Predictors of low bone mineral density in elderly males with chronic obstructive pulmonary disease: the role of body mass index

Figures & data

Table I.  Anthropometry, blood gas and spirometric parameters, nutritional, body composition and bone indices, in patients with COPD and controls.

	COPD (41), mean ± SD	Controls (41), mean ± SD
Age	75.7 ± 5.3	76.0 ± 5.8
Height (cm)	167.8 ± 6.8	169.3 ± 6.4
Weight (kg)	71.8 ± 12.1	73.9 ± 9.1
BMI (kg/m^2)	25.4 ± 3.5	25.7 ± 2.6
PaO2 (mmHg)	75.0 ± 13.1**	98.38 ± 15.8
PaCO2 (mmHg)	41.6 ± 5.2*	36.8 ± 3.9
FEV1 (l)	1.4 ± 0.5**	2.9 ± 0.6
FEV1 (% predicted)	53.1 ± 17.6**	110.9 ± 22.5
FEV1/VC (%)	48.9 ± 9.8**	73.3 ± 8.3
Albumin (g/l) (n.v. 35–52)	38.3 ± 5.4**	43.0 ± 4.7
Prealbumin (mg/l) (n.v. 200–400)	277.0 ± 63.0	301.8 ± 72.2
RBP (mg/l) (n.v. 30–60)	47.6 ± 12.8	53.6 ± 13.9
25-OH D3 (nmol/l) (n.v. > 80)	53.1 ± 41.0	42.6 ± 37.6
Total calcium (mg/dl) (n.v. 8.1–10.4)	9.5 ± 0.4	9.2 ± 0.5
Phosphate (mg/dl) (n.v. 2.5–4.8)	2.3 ± 1.0	2.7 ± 0.4
FM (kg)	18.0 ± 6.1	17.8 ± 4.8
FFM (kg)	50.7 ± 6.2**	55.3 ± 6.2
ASMM (kg)	20.9 ± 3.2*	22.6 ± 3.2
ASMMI (kg/m^2)	7.4 ± 0.9*	7.8 ± 0.8
BMD lumbar (g/cm^2)	0.95 ± 0.17**	1.08 ± 0.16
T-score lumbar	−1.47 ± 1.53**	−0.23 ± 1.46
Z-score lumbar	−0.26 ± 1.48**	0.89 ± 1.78
BMD total hip (g/cm^2)	0.85 ± 0.18	0.93 ± 0.14
T-score total hip	−1.18 ± 1.22	−0.67 ± 1.11
Z-score total hip	−0.11 ± 1.07	0.35 ± 1.26
BMD neck (g/cm^2)	0.73 ± 0.14*	0.80 ± 0.13
T-score neck	−1.54 ± 1.18*	−0.92 ± 1.17
Z-score neck	0.01 ± 1.07*	0.64 ± 1.31
BMD trochanteris (g/cm^2)	0.661 ± 0.146	0.715 ± 0.128
T-score trochanteris	−0.95 ± 1.23	−0.45 ± 1.16
Z-score trochanteris	−0.18 ± 1.09	0.34 ± 1.29

BMI, body mass index (weight ÷ height squared); FEV1, forced expiration volume after 1 s; VC, vital capacity; FFM, fat-free mass; FM, fat mass; ASMM, appendicular skeletal muscle mass; FFMI, FFM index; FMI, FM index; ASMMI, ASMM index; RBP, retinol-binding protein; BMD, bone mineral density; n.v., normal values.

COPD vs. controls (*p < 0.05,**p < 0.01).

Table II.  Simple and multiple partial R² for linear relationships between hip and lumbar spine BMD and BMI, albumin, ASMM and FEV₁.

	Total hip BMD		Lumbar BMD^†
	Simple linear, R^2	Multiple partial, R^2	Simple linear, R^2	Multiple partial, R^2
BMI	0.60**	0.62***	0.17**	0.00
ASMM (kg)	0.45**	0.01	0.20**	0.00
Albumin(g/l)	0.26**	0.00	0.15**	0.12*
FEV1 (l)	0.14*	0.08**	0.18*	0.04
	Total multiple, R^2 = 0.70		Total multiple, R^2 = 0.56
	Trochanteris BMD		Neck BMD
	Simple linear, R^2	Multiple partial, R^2	Simple linear, R^2	Multiple partial, R^2
BMI	0.41**	0.42***	0.33**	0.32***
ASMM (kg)	0.39**	0.01	0.35**	0.01
Albumin (g/l)	0.28**	0.03	0.28**	0.05*
FEV1 (l)	0.11*	0.08*	0.28*	0.09*
	Total multiple, R^2 =0.54		Total multiple, R^2 = 0.47

^†Regression model adjusted for inhaled corticosteroids (partial R² = 0.40; p < 0.001).

BMD, bone mineral density; BMI, body mass index; ASMM, appendicular skeletal muscle mass; FEV1, forced expiration volume after 1 s.

*p < 0.05; **p < 0.01;***p < 0.001.

Figure 1.  Prevalence of normal BMD (open columns), osteopenia (gray columns), osteoporosis (black columns) in patients with COPD by ASMMI class (normal: ASMMI ⩾8.4; pre-sarcopenic: 7.26 < ASMMI < 8.4; sarcopenic: ASMMI < 7.26)*, and BMI dichotomised on first tertile of distribution (25.1 kg/m²)^§. *The statistical analysis was performed comparing the prevalence of osteoporosis between groups: Cochran-Armitage test for trend: p < 0.05; ^§Exact Fisher's test: p < 0.02.