J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 12, Number 7, July 2020, pages 436-442

Association Between Low Vitamin D Levels and the Greater Impact of Fibromyalgia

**Table 1.** FM Patients’ Featuring (Qualitative Variables)
Variables	n	Percentage
^aExposure to sunlight for at least half an hour a day, or at least 3 - 4 h a week. ^bStaying indoors most of the days. FM: fibromyalgia.
Age group
23 to 30 years	3	7.0
31 to 40 years	14	32.6
41 to 50 years	11	25.6
51 to 60 years	15	34.8
Skin phototype
I	4	9.3
II	9	20.9
III	21	48.9
IV	4	9.3
V	5	11.6
Smoking
Yes	7	16.3
No	36	83.7
Alcohol consumption
Yes	3	7.0
No	40	93.0
Exercising
Yes	15	34.9
No	28	65.1
Exposure to the sunlight^a
Yes	26	60.4
No	15	34.9
No information	2	4.7
Indoors^b
Yes	27	62.7
No	14	32.6
No information	2	4.7

Table 1. FM Patients’ Featuring (Qualitative Variables)

Variables

Percentage

^aExposure to sunlight for at least half an hour a day, or at least 3 - 4 h a week. ^bStaying indoors most of the days. FM: fibromyalgia.

Age group

23 to 30 years

7.0

31 to 40 years

32.6

41 to 50 years

25.6

51 to 60 years

34.8

Skin phototype

9.3

20.9

III

48.9

9.3

11.6

Smoking

Yes

16.3

83.7

Alcohol consumption

Yes

7.0

93.0

Exercising

Yes

34.9

65.1

Exposure to the sunlight^a

Yes

60.4

34.9

No information

4.7

Indoors^b

Yes

62.7

32.6

No information

4.7

**Table 2.** Comparison Between Vitamin D Concentrations Based on Variables Investigated in Fibromyalgia Patients
Variables	n	Vitamin D concentration
^aKruskal-Wallis test. ^bMann-Whitney test. ^cExposure for at least half an hour a day, or at least 3 -4 h a week. ^dStaying indoors most of the days.
Skin phototype			0.889^a
I	4	38.1 ± 12.9
II	9	34.9 ± 13.0
III	21	34.2 ± 10.1
IV	4	39.8 ± 20.7
V	5	30.3 ± 12.5
Smoking			0.070^b
Yes	7	40.2 ± 10.5
No	36	33.7 ± 12.1
Alcohol consumption			0.431^b
Yes	3	35.8 ± 2.1
No	40	34.7 ± 12.5
Exposure to the sunlight^c			0.001^b
Yes	26	39.5 ± 12.6
No	15	27.1 ± 6.4
Indoors^d			0.022^b
Yes	27	31.9 ± 11.0
No	14	40.9 ± 12.8
Exercising			0.516^b
Yes	15	33.4 ± 12.3
No	28	35.5 ± 12.0

Table 2. Comparison Between Vitamin D Concentrations Based on Variables Investigated in Fibromyalgia Patients

Variables

Vitamin D concentration

Mean ± standard deviation

P value

^aKruskal-Wallis test. ^bMann-Whitney test. ^cExposure for at least half an hour a day, or at least 3 -4 h a week. ^dStaying indoors most of the days.

Skin phototype

0.889^a

38.1 ± 12.9

34.9 ± 13.0

III

34.2 ± 10.1

39.8 ± 20.7

30.3 ± 12.5

Smoking

0.070^b

Yes

40.2 ± 10.5

33.7 ± 12.1

Alcohol consumption

0.431^b

Yes

35.8 ± 2.1

34.7 ± 12.5

Exposure to the sunlight^c

0.001^b

Yes

39.5 ± 12.6

27.1 ± 6.4

Indoors^d

0.022^b

Yes

31.9 ± 11.0

40.9 ± 12.8

Exercising

0.516^b

Yes

33.4 ± 12.3

35.5 ± 12.0

**Table 3.** Comparison of Analyzed Variables Between Fibromyalgia Patients and Controls
Variables	Patients	Controls	P value
^aMean ± standard deviation. ^bMann-Whitney test. ^cChi-square test. ^dFisher’s exact test. ^eCurrent smokers. ^fDaily or sporadic alcohol drinker. ^gRegular exercisers.
Age^a	44.3 ± 10.2	41.2 ± 11.5	0.232^b
Body mass index (kg/m²)^a	27.8 ± 5.7	26.2 ± 5.4	0.222^b
Vitamin D^a	34.8 ± 12	34.7 ± 12.3	0.806^b
Deficient, n (%)	3 (7.0)	0 (0.0)
Insufficient, n (%)	15 (34.8)	20 (50.0)	0.132^c
Normal, n (%)	25 (58.1)	20 (50.0)
Skin phototype, n (%)			0.023^d
I	4 (9.3)	-
II	9 (20.9)	15 (37.5)
III	21 (48.8)	19 (47.5)
IV	4 (9.3)	6 (15.0)
V	5 (11.6)	-
Smoking^e, n (%)	7 (16.0)	1 (2.5)	0.059^d
Alcohol consumption^f, n (%)	3 (7.0)	1 (2.5)	0.617^d
Exercising^g, n (%)	15 (34.9)	10 (25.0)	0.350^d

Table 3. Comparison of Analyzed Variables Between Fibromyalgia Patients and Controls

Variables

Patients

Controls

P value

^aMean ± standard deviation. ^bMann-Whitney test. ^cChi-square test. ^dFisher’s exact test. ^eCurrent smokers. ^fDaily or sporadic alcohol drinker. ^gRegular exercisers.

Age^a

44.3 ± 10.2

41.2 ± 11.5

0.232^b

Body mass index (kg/m²)^a

27.8 ± 5.7

26.2 ± 5.4

0.222^b

Vitamin D^a

34.8 ± 12

34.7 ± 12.3

0.806^b

Deficient, n (%)

3 (7.0)

0 (0.0)

Insufficient, n (%)

15 (34.8)

20 (50.0)

0.132^c

Normal, n (%)

25 (58.1)

20 (50.0)

Skin phototype, n (%)

0.023^d

4 (9.3)

9 (20.9)

15 (37.5)

III

21 (48.8)

19 (47.5)

4 (9.3)

6 (15.0)

5 (11.6)

Smoking^e, n (%)

7 (16.0)

1 (2.5)

0.059^d

Alcohol consumption^f, n (%)

3 (7.0)

1 (2.5)

0.617^d

Exercising^g, n (%)

15 (34.9)

10 (25.0)

0.350^d

**Table 4.** Correlation Between Clinical and Laboratory Variables Investigated in the Control Group
Variables	Vitamin D concentration
FIQ: fibromyalgia impact questionnaire; VAS: visual analogue scale.
Age	-0.094	0.398
FIQ	-0.360	0.018
VAS	-0.221	0.155
Body mass index (kg/m²)	-0.169	0.126
Calcium	0.139	0.376
Albumin (g/dL)	0.070	0.658
Phosphorus (mg/dL)	-0.065	0.678
Parathyroid hormone (Unit)	-0.383	0.011

Table 4. Correlation Between Clinical and Laboratory Variables Investigated in the Control Group

Variables

Vitamin D concentration

Spearman’s correlation coefficient

P value

FIQ: fibromyalgia impact questionnaire; VAS: visual analogue scale.

Age

-0.094

0.398

FIQ

-0.360

0.018

VAS

-0.221

0.155

Body mass index (kg/m²)

-0.169

0.126

Calcium

0.139

0.376

Albumin (g/dL)

0.070

0.658

Phosphorus (mg/dL)

-0.065

0.678

Parathyroid hormone (Unit)

-0.383

0.011