Vitamin D Status and Longitudinal Changes in Body Composition in Patients with Chronic Obstructive Pulmonary Disease – A Prospective Observational Study

Figures & data

Figure 1 Flow chart of participants included in the study.

Table 1 Baseline Characteristics of the Participants

Variables	COPD n=192	Controls n=199	p-value
Male n (%)	109 (57)	89 (45)	0.02^a
Age, years mean (SD)	62 ± 7	61 ± 7	0.03^b
Smoking status
Former smoker n (%)	162 (84)	114 (57)
Current smoker n (%)	27 (14)	26 (13)
Non-smoker n (%)	3 (2)	59 (30)
Number of pack years smoked	43 (31–59)	7 (0–20)	<0.001^c
Vitamin D level
Plasma 25(OH)D nmol/L	64 ± 26	75 ± 25	<0.001^b
Body Composition
BMI (kg/m^2)	26.6 ± 5	26.9 ± 3.4	0.51^b
BMI <18.5 n (%)	10 (5)	0 (0)
BMI 18.5–24.9 n (%)	60 (31)	60 (30)
BMI 25–29.9 n (%)	70 (36)	107 (54)
BMI <30 n (%)	52 (27)	32 (16)
FFMI (kg/m^2)	17.6 ± 2.6	17.9 ± 2.3	0.19^b
FMI (kg/m^2)	9.0 ± 3.7	8.9 ± 2.9	0.89^b
BMD hip (g/cm^2)	0.84 (0.77–0.92)	0.94 (0.85–1.04)	<0.001^c
BMD lumbar spine (g/cm^2)	1.10 (0.95–1.22)	1.20 (1.05–1.3)	<0.001^c
T-score hip	−1.5 (−2.1 – −0.9)	−0.7 (−1.3–0.1)	<0.001^c
T-score lumbar spine	−1 (−1.7–0.1)	0 (−1.2–1.1)	<0.001^c
Lung function
FEV1% predicted	49 ± 16	119 ± 15	<0.001^b
FVC % predicted	98 ± 21	124 ± 16	<0.001^b
FEV1/FVC ratio	41 ± 11	79 ± 4	<0.001^b
Self-reported medications
Calcium- vitamin D supplements n (%)	28 (15)	3 (2)	<0.001^a
Comorbidities
Osteopenia, n (%)	104 (54)	77 (39)	0.002^a
Osteoporosis, n (%)	39 (21)	14 (7)	<0.001^a
Self-reported Diabetes mellitus, n (%)	13 (7)	6 (3)	0.08^a
Self-reported Hypertension, n (%)	43 (22)	42 (21)	0.80^a
Self-reported Cardiac disease, n (%)	39 (20)	9 (5)	<0.001^a
Self-reported Gastrointestinal disease, n (%)	20 (10)	9 (5)	0.026^a
≥ 2 exacerbations in the previous year	86 (45)	-
≥ 1 hospital admission in the previous year	60 (31)	-
6MWT, m	465 ± 113	-
Questionnaires
mMRC, score	3 ± 1	-
SGRQ, Total score	54.8 ±16.7	-

Notes: Data are presented as mean ± SD or median (quartiles 1 and 3), unless otherwise stated. ^aPearson Chi-squared test. ^bIndependent samples t-test. ^cIndependent samples Mann Whitney U-test.

Abbreviations: COPD, chronic obstructive pulmonary disease; 25(OH)D, 25-hydroxyvitamin D; BMI, Body mass index; FFM, fat-free mass; FM, fat mass; FFMI, Fat-free mass index; FMI, Fat-mass index; BMD, Bone mineral density; FEV1% predicted, forced expiratory volume in the first second in percent of predicted value; FVC % predicted, forced vital capacity in percent of predicted value; 6MWT, Six-minute walk test; mMRC, Modified Medical Research Council; SGRQ, St George Respiratory Questionnaire.

Figure 2 Vitamin D levels in patients with COPD and controls.

Abbreviations: 25(OH)D, 25-hydroxyvitamin D; COPD, Chronic obstructive pulmonary disease.

Table 2 Baseline Characteristics by Vitamin D Status

Variables	COPD Vitamin D Insufficiency	COPD Vitamin D Sufficiency	p-value	Controls Vitamin D Insufficiency	Controls Vitamin D Sufficiency	p-value
	n=65	n=127		n=31	n=168
Male n (%)	40 (62)	69 (54)	0.34^a	14 (45)	75 (45)	0.96^a
Age, years	61 ± 8	63 ± 7	0.32^b	62 ± 7	61 ± 7	0.48^b
Current smoker n (%)	13 (20)	14 (11)	0.09^a	3 (10)	23 (14)	0.54^a
Body composition
BMI (kg/m^2)	26.3 ± 4.9	26.7 ± 5	0.61^b	27.7 ± 3.5	26.7 ± 3.4	0.13^b
BMI <18.5 n (5) n (%)	3 (5)	7 (6)		0 (0)	0 (0)
BMI 18.5–24.9 n (%)	22 (34)	38 (30)		7 (23)	53 (32)
BMI 25–29.9 n (%)	24 (37)	46 (36)		16 (52)	91 (54)
BMI >30 n (%)	16 (25)	36 (28)		8 (26)	24 (14)
FFMI (kg/m^2)	17.5 ± 2.3	17.7 ± 2.7	0.55^b	18.3 ± 2.3	17.9 ± 2.3	0.38^b
FMI (kg/m^2)	8.9 ± 3.7	9 ± 3.7	0.78^b	9.5 ± 3.2	8.9 ± 2.9	0.27^b
T-score hip	−1.5 (−2.1 – −1)	−1.5 (−2.1 – −0.8)	0.33^c	−1.0 (−1.5–0)	−0.7 (−1.3–0.2)	0.29^c
T-score lumbar spine	−1.1 (−1.9–0)	−1 (−1.7–0.1)	0.47^c	−0.2 (−1.3–0.6)	0.1 (−1.2–1.1)	0.26^c
Lung function
FEV1% predicted	46 ± 16	51 ± 16	0.03^b	118 ± 16	119 ± 15	0.60^c
FVC % predicted	95 ± 19	100 ± 22	0.10^b	121 ± 18	125 ± 16	0.19^b
FEV1/FVC ratio, %	39 ± 12	42 ± 11	0.15^b	80 ± 5	78 ± 5	0.14^b
Comorbidities
Osteopenia n (%)	38 (58)	66 (52)	0.39^a	16 (52)	61 (36)	0.11^a
Osteoporosis n (%)	15 (23)	24 (19)	0.50^a	2 (6)	12 (7)	0.89^a
Self-reported Gastrointestinal disease	8 (12)	12 (9)	0.54^a	1 (3)	8 (5)	0.71^a
≥ 2 exacerbations in the previous year n (%)	29 (45)	57 (45)	0.94^a	-	-
≥ 1 hospital admission in the previous year n (%)	27 (42)	33 (26)	0.03^a
6MWT, m	438 ± 106	481 ± 114	0.03^b	-	-
Questionnaires
mMRC, grade	3 ± 1	3 ± 1	0.15^b	-	-
SGRQ, Total score	59 ± 17.4	52.6 ± 15.9	0.02^b	-	-

Notes: Data are presented as median (quartiles 1 and 3) or mean ±SD unless otherwise stated. Vitamin D insufficiency = 25-hydroxyvitamin D <50 nmol/L and Vitamin D sufficiency = 25-hydroxyvitamin D ≥50 nmol/L. ^aPearson Chi Squared test. ^bIndependent samples t-test. ^cIndependent samples Mann Whitney U-test.

Abbreviations: COPD, chronic obstructive pulmonary disease; BMI, body mass index; FFMI, fat-free mass index; FMI, fat-mass index; FEV1% predicted, Forced expiratory volume in the first second in percent of predicted value; FVC % predicted, Forced vital capacity in percent of predicted value; 6MWT, Six-minute walk test; mMRC, Modified Medical research Council dyspnoea scale; SGRQ, St George Respiratory Questionnaire.

Table 3 Changes in Body Composition Over Two Years

	COPD Baseline	COPD Year 2	p-value	Control Baseline	Control Year 2	p-value
BMI, kg/m^2	26.6 ± 5.0	27.0 ± 5.3	0.62^a	26.9 ± 3.4	27.0 ± 3.6	0.13^a
FFMI, kg/m^2	17.7 ± 2.6	17.3 ± 2.5	<0.001^a	17.9 ± 2.3	17.8 ± 2.2	0.002^a
FMI, kg/m^2	9.1 ± 3.6	9.5 ± 3.7	0.002^a	8.9 ± 2.9	9.2 ± 3	0.006^a
T-score hip	−1.4 (−2.1–0.9)	−1.7 (−2.2 – −1.1)	<0.001^b	−0.7 (−1.4–0.1)	−0.9 (−1.6–0.2)	<0.001^b
T-score lumbar spine	−1.0 (−1.7–0.3)	−0.9 (−2.1–0.2)	0.81^b	0 (−1.3–1.1)	0 (−1.4–1.2)	0.98^b

Notes: Data are presented as mean ± SD or median (quartiles 1 and 3). ^aPaired samples t-test. ^bRelated samples Wilcoxon sign rank test.

Abbreviations: COPD, chronic obstructive pulmonary disease; BMI, Body mass index; FFMI, Fat-free mass index; FMI, Fat-mass index.

Table 4 Multiple Linear Regression Analyses to Assess the Relationship Between 25(OH)D (Nmol/l) and Longitudinal Changes in Body Composition

Dependent Variable	Model 1		Model 2
	B (SE)	p-value	B (SE)	p-value
Δ BMI^a* n=356	−0.002 (0.003)	0.53	−0.003 (0.003)	0.47
Δ FFMI^b*,^c* n=353	0.002 (0.001)	0.25	0.001 (0.001)	0.34
Δ FMI^d* n=353	−0.003 (0.003)	0.33	−0.004 (0.003)	0.25
Δ T-score hip^e* n=345	−0.003 (0.001)	0.01	−0.001 (0.001)	0.19
Δ T-score lumbar spine^f*,^g* n=351	−0.002 (0.001)	0.15	−0.001 (0.001)	0.21

Notes: Model 1, adjusted for sex (female vs male) and group (control vs COPD). Model 2, adjusted for sex (female vs male), group (control vs COPD) age, smoking status (former or non-smoker vs current smoker) and baseline value of the dependent body composition variable being analysed. *p<0.05. ^aModel 2, Age B −0.029 (0.013). ^bModel 1, Gender: B −0.221 (0.068), Group: B −0.239 (0.069). ^cModel 2, Group: B −0.265 (0.070), Baseline value of FFMI: B-0.059 (0.022). ^dModel 2, Baseline value of FMI: B −0.067 (0.025). ^eModel 2, Gender: B 0.131 (0.052), Group: B −0.209 (0.054), Baseline value of T-score hip: B −0.233 (0.025). ^fModel 1, Gender: B 0.173 (0.053). ^gModel 2, Gender: B 0.178 (0.056). Statistical significance was set at p < 0.05.

Abbreviations: Δ, change over two years in the dependent variable analysed; B, unstandardized B-coefficient; SE, standard error; 25(OH)D, 25-Hydroxyvitamin D; COPD, chronic obstructive pulmonary disease; BMI, Body mass index, FFMI, Fat-free mass index; FMI, Fat-mass index.

Figure 3 Changes in Body composition over two years by vitamin D status.

Notes: Δ BMI = BMI year 2 – BMI at baseline. Δ FFMI = FFMI year 2 – FFMI at baseline. Δ FMI = FMI at year 2 – FMI at baseline. Δ T-score hip = T-score hip at year 2 - T-score hip at baseline. Δ T-score lumbar spine = T-score lumbar spine at year 2 - T-score lumbar spine at baseline.

Abbreviations: BMI, body mass index; COPD, chronic obstructive pulmonary disease; FFMI, Fat-free mass index; FMI, Fat-mass index.