Association between airflow limitation severity and reduced bone mineral density in Japanese men

Figures & data

Figure 1 Flow chart for selecting the subjects with AL or normal pulmonary function. AL air flow limitation, FEV₁ forced expiratory in 1s.

Table 1 The characteristics of the subjects based on pulmonary function

	Normal pulmonary function n=217	Mild AL n=52	Moderate-to-severe AL n=21	p-value
Age, yr	70.0 (12.0)	78.1 (7.5)**	77.3 (7.3)*	<0.001
Height, cm	164.9 (5.9)	163.3 (6.9)	164.2 (5.9)	0.259
Weight, kg	62.5 (9.8)	60.4 (8.0)	59.6 (7.3)	0.174
Abdominal circumference, cm	84.3 (8.5)	84.1 (6.5)	84.2 (7.7)	0.988
BMI, kg/m^2	23.0 (3.1)	22.6 (2.2)	22.1 (2.5)	0.375
Systolic blood presure, mmHg	128.7 (16.0)	131.0 (15.2)	127.5 (14.1)	0.579
Diastolic blood pressure, mmHg	73.7 (10.2)	73.5 (9.2)	73.2 (9.9)	0.965
Smoking status, n (%)
Never smokers	85 (39.2)	16 (30.8)	2 (9.5)
Former smokers	120 (55.3)	30 (57.7)	16 (76.2)
Current smokers	12 (5.5)	6 (11.5)	3 (14.3)	0.036
Pack-years	13.0 (16.7)	22.5 (25.1)*	37.0 (26.2)^** #	<0.001
Physical activity, n (%)
Regular	72 (33.2)	22 (42.3)	7 (33.3)
Inactive	145 (66.8)	30 (57.7)	14 (66.7)	0.458
Alcohol drinking, n (%)
Non	64 (29.5)	19 (36.5)	8 (38.1)
1–6 days per week	106 (48.8)	18 (34.6)	10 (47.6)
Daily	47 (21.7)	15 (28.9)	3 (14.3)	0.346
Pulmonary function
FVC, mL	3,591.5 (641.9)	3,581.9 (657.6)	2,985.2 (469.5)^** ##	<0.001
FEV1, mL	2,758.0 (517.4)	2,326.2 (414.8)**	1,774.3 (330.6)^** ##	<0.001
FEV1/FVC, %	76.9 (5.6)	65.1 (3.5)**	60.1 (9.2)^** ##	<0.001
FEV1% predicted, %	98.9 (11.1)	92.8 (9.5)**	69.2 (9.3)^** ##	<0.001
Laboratory data
Fasting glucose, mg/dL (n=244)	104.7 (15.5)	101.8 (11.8)	101.2 (10.2)	0.342
Triglycerides, mg/dL
(interquartile range)	81.0 (64.0–121.0)	86.5 (70.5–115.5)	100.0 (64.0–125.0)	0.531
HDL cholesterol, mg/dL	63.8 (15.1)	64.3 (15.7)	62.2 (15.5)	0.873
LDL cholesterol, mg/dL	119.1 (28.6)	123.2 (25.1)	111.2 (30.9)	0.259
White blood cell count, /μL	5,100.0 (1,398.8)	5,223.1 (1,595.5)	5,609.5 (1,474.4)	0.285
hsCRP
(interquartile range)	0.06 (0.03–0.12)	0.07 (0.05–0.13)	0.08 (0.05–0.16)*	<0.05

Notes: Data are expressed as means (standard deviation), median (interquartile range), or as number (n) (percentage) Airflow limitation (AL) was defined as FEV₁/FVC < 0.7. Pack years = (number of cigareetes smoked per day x number of year smokedy)/20. BMI body mass index, FVC forced vital capacity, FEV₁ forced expiratory volume in one second, HDL high-density lipoprotein, LDL low-density lipoprotein, hsCRP hypersensitivity C-reactive protein. *p < 0.05, **p < 0.01 compared with normal pulmonary function. ^#p < 0.05, ^##p < 0.01 compared with mild airflow limitation.

Table 2 Prevalence of reduced bone mineral density according to AL severity

	AL severity
	Normal	Mild	Moderate-to-severe	p-value
Number of participants	217	52	21
Reduced bone mineral density	104 (47.9)	30 (57.7)	16 (76.2)	0.030
Osteopenia	86 (39.6)	23 (44.2)	15 (71.4)
Osteoporosis	8 (3.7)	1 (1.4)	0 (0)
Medication used for osteoporosis	10 (4.6)	6 (11.5)	1 (4.8)

Notes: Data are expressed as number (n) (percentage). Airflow limitation (AL) was defined as FEV₁/FVC < 0.7. Reduced bone mineral density was defined as osteopenia, osteoporosis, or medication used for osteoporosis.

Table 3 Association between AL and reduced bone mineral density according to pulmonary function

		AL
	Normal pulmonary function, n=217	Mild AL, n=52	p-value	Moderate-to-severe AL, n=21	p-value
Crude	Reference	1.48 (0.80–2.73)	0.207	3.48 (1.23–9.83)	0.019
Adjusted	Reference	1.38 (0.69–2.78)	0.366	3.87 (1.20–12.49)	0.024

Notes: Adjusted for age, body mass index, pack-years, physical activity, and alcohol drinking Airflow limitation (AL) was defined as FEV₁/FVC < 0.7.