The influence of disease severity and lifestyle factors on the peak annual 25(OH)D value of COPD patients

Figures & data

Table 1 Characteristics of the study sample controls (column A) vs COPD subjects (column B) and COPD subjects without vitamin D deficiency (defined as 25(OH)D $50 nmol/L; column C) vs COPD subjects with deficiency of vitamin D (column D)

Characteristics	A	B	C	D	p-value
	Control	COPD	COPD	COPD	A vs B	C vs D
			≥50 nmol/L	<50 nmol/L
Subjects, n	47	66	32	34
Gender, % females	68	55	59	50	ns	ns
Mean age (years), mean (SD)	70 (10)	70 (9)	70 (8)	69 (10)	ns	ns
Current smoker, %/n	2/1	17/11	9/3	24/8	<0.05	ns
Ex-smoker, %/n	40/19	76/50	78/25	74/25	<0.01	ns
Never smoker, %/n	58/27	8/5	13/4	3/1	<0.001	ns
BMI (kg/m^2), mean (SD)	25.9 (3.4)	26.3 (7.1)	25.7 (6.7)	26.8 (7.5)	ns	ns
CCI 0–1, %/n	83/39	47/31	56/18	38/13	<0.05	ns
CCI 2–3, %/n	17/8	36/24	28/9	44/15	<0.05	ns
CCI ≥4, %/n	0	17/11	16/5	18/6	<0.05	ns
FEV1 % predicted, mean (SD)	105 (16)	41 (16)	41 (16)	41 (17)	<0.001	ns
I–II (FEV1 50–100), %/n	na	30/20	22/7	38/13		ns
III–IV (FEV1 0–49), %/n	na	70/46	78/25	62/21		ns
Exacerbation(s), mean (SD)	na	1.67 (1.83)	1.3 (1.6)	2.00 (1.97)		ns
GOLD category A–B, %/n	na	18/12	16/6	18/6		ns
GOLD category C–D, %/n	na	82/54	84/26	82/28		ns
PaO2, kPa (air), mean (SD)	na	8.5 (1.6)	8.2 (1.5)	8.5 (1.6)		ns
SAT, % (air), mean (SD)	98 (2)	91.6 (6.0)	92 (6)	92 (6)	<0.001	ns
LTOT, %/n	na	28/42	13/46	15/54		ns
DOSE index, mean (SD)	na	3.6 (1.8)	3.3 (1.7)	4.0 (1.8)		ns
Inhaled steroids, %/n	0	97/64	97/31	97/33		ns
Oral steroids, %/n	0	15/10	12/4	18/6		ns
Vitamin D suppl., %/n	21/10	29/18	53/17	3/1	ns	<0.05
mMRC (0–4), mean (SD)	na	2.8 (1.2)	2.6 (1.2)	3.1 (1.1)		ns
CAT (0–40), mean (SD)	na	20.3 (7.4)	17.8 (7.0)	22.5 (7.5)		<0.01
SGRQ sympt., mean (SD)	na	59 (22)	51 (22)	66 (20)		<0.01
SGRQ activity, mean (SD)	na	75 (18)	71 (20)	78 (16)		ns
SGRQ impact, mean (SD)	na	46 (21)	42 (22)	49 (20)		ns
SGRQ total, mean (SD)	na	57 (18)	53 (19)	61 (16)		ns
SPS, mean (SD)	1.4 (0.5)	1.4 (0.5)	1.4 (0.5)	1.3 (0.5)	ns	ns
Portion size, mean (SD)	2.1 (0.6)	1.8 (0.6)	2.0 (0.6)	1.7 (0.6)	<0.05	ns
MDS, mean (SD)	21.9 (3.9)	18.7 (3.7)	19.0 (3.3)	18.5 (4.1)	<0.0001	ns
Omega-3 index, mean (SD)	5.79 (1.40)	5.16 (1.36)	5.43 (1.43)	4.90 (1.23)	<0.05	ns
UVS, mean (SD)	4.74 (1.10)	3.84 (1.82)	4.44 (1.52)	3.26 (1.92)	<0.01	<0.01
General
Hemoglobin, mean (SD) (134–170 g/L)	na	143 (13)	143 (13)	143 (13)		ns
Creatinine, mean (SD) (49–90 µmol/L)	na	78 (25)	78 (22)	79 (28)		ns
Albumin, mean (SD) (36–45 g/L)	na	38.1 (3.3)	38.9 (2.6)	37.4 (3.7)		ns
Urea, mean (SD) (3.5–8.2 mmol/L)	na	7.3 (3.1)	7.0 (2.5)	7.7 (3.6)		ns
Inflammation
WBC, mean (SD) (3.5–8.8×10*^9/L)	na	9.0 (2.6)	8.6 (2.2)	9.4 (3.0)		ns
hs-CRP, mean (SD) (<3 mg/L)	na	7.3 (13.3)	4.9 (5.6)	9.6 (17.5)		ns
Fibrinogen, mean (SD) (2–4 g/dL)	na	3.7 (1.0)	3.6 (0.8)	3.7 (1.2)		ns
IL-6, mean (SD) (<7 ng/L)	na	6.9 (12.8)	4.1 (2.6)	9.6 (17.3)		ns
Bone metabolism
PTH, mean (SD) (15–65 ng/L)	na	65.4 (39.9)	60.1 (26.9)	70.4 (48.8)		ns
Ionized Ca, mean (SD) (1.18–1.34 nmol/L)	na	1.26 (0.05)	1.26 (0.05)	1.26 (0.06)		ns
Phosphate, mean (SD) (0.75–1.40 mmol/L)	na	1.06 (0.23)	1.08 (0.26)	1.04 (0.21)		ns
ALP, mean (SD) (0.6–1.8 µkat/L)	na	0.9 (0.3)	0.9 (0.3)	0.9 (0.3)		ns
25-(OH)D, mean (SD)	74.0 (16.0)	50.4 (22.8)	69.2 (16.2)	32.6 (10.5)	<0.0001	<0.0001

Notes: Results are presented as mean (± SD) for continuous variables and percentage for categorical variables (p-value A vs B and C vs D). p-values are from chi-square test (nominal data), Student’s t-test (normally distributed data) or Mann–Whitney U-test (not normally distributed data). na, not analyzed (reference values stated in parenthesis); ns, not significant (p-value ≥0.05).

Abbreviations: ALP, alkaline phosphatase; BMI, body mass index; CAT, COPD Assessment Test; CCI, Charlson Comorbidity Index; DOSE, Dyspnoea, Obstruction, Smoking, Exacerbation; FEV₁, forced expiratory volume in 1 second; GOLD, Global initiative for chronic Obstructive Lung Disease; hs-CRP, high-sensitivity C-reactive protein; IL-6, interleukin 6; LTOT, long-term oxygen therapy; MDS, Mediterranean Diet Score; mMRC, modified British Medical Research Council; PTH, parathyroid hormone; SAT, blood oxygen saturation; SGRQ, St George’s Respiratory Questionnaire; SPS, Skin pigmentation score; suppl, supplement; UVS, Ultraviolet Score; WBC, white blood cell.

Figure 1 Peak annual values of 25(OH)D in controls (n=47) and COPD subjects without LTOT (n=38) and with LTOT (n=28).

Notes: Open symbols represent subjects without vitamin D supplementation and filled symbols represent those supplemented with vitamin D. The dotted lines indicate the upper limits for the definition of insufficiency (75 nmol/L) and severe deficiency (25 nmol/L). The lines in each scatter dot plot indicate mean for each group. Student’s t-test was used for comparison of normally distributed groups; for details see the “Subjects and methods” section.
Abbreviation: LTOT, long-term oxygen therapy.

Figure 2 All COPD subjects (n=66).

Notes: Correlations between peak annual value of 25(OH)D and (A) CAT score, (B) omega-3 index and (C) UVS. The Pearson’s coefficient of determination was calculated as indicated.
Abbreviations: CAT, COPD Assessment Test; UVS, Ultraviolet Score.

Figure 3 COPD subjects with values <50 nmol/L without vitamin D supplementation (n=33).

Note: Correlations between peak annual value of 25(OH)D and (A) FEV₁ % predicted, (B) SAT, (C) MDS and (D) UVS.
Abbreviations: FEV₁ % predicted, forced expiratory volume in 1 second as % predicted; MDS, Mediterranean Diet Score; SAT, blood oxygen saturation; UVS, Ultraviolet Score.