Prevalence of vitamin D deficiency among Iranian adolescents

Developing a Model for Prediction of Serum 25-Hydroxyvitamin D Level: The Use of Linear Regression and Machine Learning Methods

OBJECTIVE

Because vitamin D status affects many organs and tissues of the body, it is important to determine the factors affecting it. The purpose of this study was to develop a model for predicting the serum 25-hydroxyvitamin D [25(OH)D] level in healthy young adults.

METHOD

This cross-sectional study was conducted on 201 healthy individuals aged 20 to 40 years old in Shiraz, Iran. Data regarding demographic characteristics, vitamin D intake through supplements, and sun exposure habits were gathered. Serum 25(OH)D concentration was also measured. Data were analyzed with R software using linear regression and different machine learning methods such as conditional tree, conditional forest and random forest.

RESULTS

Based on the linear regression, male sex (p < 0.001), taking 50,000 IU vitamin D₃ supplement monthly (p < 0.001), and lower waist circumference (p = 0.018) were identified as effective factors in increasing serum 25(OH)D levels. According to the conditional tree, taking 50,000 IU vitamin D₃ supplement monthly (p < 0.001) and sex (p < 0.001) were two main factors in the classification of individuals in terms of serum 25(OH)D levels. Besides, conditional forest and random forest results showed that the most important variable was taking 50,000 IU vitamin D₃ supplement monthly.

CONCLUSIONS

Supplement use is the first and most important predictor of 25(OH)D levels and other factors, including sex and waist circumference, are ranked thereafter, and the importance of these factors is greater in those who do not take vitamin D₃ supplements.

Spirometry, cardiopulmonary exercise testing and the six-minute walk test results in sarcoidosis patients

Background

The 6-minute walking test, cardiopulmonary exercise testing, and spirometry are useful tools for evaluation of respiratory impairment and functional capacity in patients with lung disease. Sarcoidosis is a multisystem granulomatous disease of unknown etiology.

Objectives

Since the pulmonary involvement can affect the quality of life in sarcoidosis patients, this study is aimed to evaluate the tests mentioned above in order to examine the functional capacity of sarcoidosis patients in different stages as well as the cause of exercise intolerance.

Methods

This cross-sectional study was carried out on 50 Iranian patients with sarcoidosis. Patients were classified into three groups based on the findings of the chest radiography as well as the pulmonary CT scan, reported by an expert radiologist. Pulmonary, cardiac, and activity function have been evaluated in the patients, using cardiopulmonary exercise testing, the 6-minutes walking test, and spirometry.

Results

In cardiopulmonary exercise testing, percent-predicted peak VO₂ (57.75±15.49, p=0.015) and percent-predicted O₂ pulse (70.54±17.37, p=0.013) were significantly lower in the third group, in comparison with the others. Also, VE/CO₂ (AT) (34.99±5.67, p=0.000) was significantly higher in the third group, in comparison with the other ones. Percent-predicted VO₂ showed a strong positive correlation with age (r=0.377, p=0.009), TSH (r= 0.404, p=0.007), and percent-predicted FVC (r=0.443, p=0.002). In addition, O₂ pulse had a positive correlation with BMI (r=0.324, p=0.026), percent-predicted FVC (r=0.557, p= 0.000), and percent-predicted FEV₁ (r=0.316, p=0.032).

Conclusions

According to this study, ventilatory limitation, pulmonary involvement, and deconditioning are the main causes of activity limitations in sarcoidosis patients.

Chronic rhinosinusitis with polyposis and serum vitamin D levels

The pathogenesis of chronic rhinosinusitis (CRS) is still unknown, but it is accepted that various inflammatory factors are responsible for the different CRS subtypes. Vitamin D3 has been shown to alter inflammatory mediators in some diseases and its deficiency might also be associated with CRS with nasal polyposis (CRSwNP). Herein, we investigated serum vitamin D3 levels in patients with CRSwNP and its association with disease severity. In a cross-sectional study, 166 cases with CRSwNP and 172 healthy subjects were enrolled. Serum vitamin D3 levels were measured and compared in both groups. Furthermore, the relationship between serum vitamin-D3 level and the patient’s allergic status and severity of disease (clinically and based on computed tomographic imaging and nasal endoscopy) among patients with CRSwNP was assessed. Serum vitamin D3 level in the CRSwNP group was significantly lower than in the control group (P < 0.0001). After controlling for possible confounding factors, an increase in vitamin D level showed a protective effect in CRSwNP (OR = 0.69 95% CI:0.62-0.76). A negative correlation was found between serum vitamin-D3 level and the Lund-Mackay score (LMS) (P < 0.0001, R = – 0.66), the Lund-Kennedy score (LKS) (P < 0.0001, R = – 0.71) and the Sino-Nasal Outcome Test-22 (P < 0.001, R = – 0.49). Serum vitamin D level in the CRSwNP group was significantly lower than the control group. Disease severity, based on imaging, endoscopic and clinical criteria, was inversely associated with serum vitamin D levels.

Factors that influence dietary behavior toward iron and vitamin D consumption based on the theory of planned behavior in Iranian adolescent girls

Background

The impact of iron and vitamin D supplements among adolescent is not well understood. The prevalence of supplement use, and the behavioral intentions of adolescents was studied to better understand the data on supplement intake. We used the theory of Planned Behavior (TPB) to explore the determinants that influence supplement intake, and its potential constructs to examine determinants that influence dietary supplement behavior towards the use of iron and vitamin D supplements amongst a sample of Iranian schoolgirl.

Methods

This was a cross-sectional study of 485 adolescent girls aged 12–17 years. Multiple analytical models including hierarchical regression and structural equation modeling (SEM) were used to examine the association between TPB constructs and adolescent’s behavioral intentions to consume dietary supplements.

Results

Based on the results of SEM, constructs of TPB and knowledge were found to predict 74% of the variation in the behavioral intentions of the schoolgirls. SEM indicated that perceived behavioral control (PBC) and knowledge had significant associations with intention behaviors to take nutritional supplements.

Conclusion

TPB and its constructs were used to establish the determinants of iron and vitamin D intake among schoolgirls in Iran. This outcome indicates that efforts to promote behavioral intentions through targeting subjective norms, attitude, and PBC may promote supplement use.

Prevalence of vitamin D deficiency in healthy Iranian children: A systematic review and meta-analysis

Background: Vitamin D deficiency is related to rickets in children, and it can increase the risk of osteoporosis in adulthood. The aim of our study was to estimate the prevalence of vitamin D deficiency among healthy Iranian children and adolescents. Vitamin D levels less than 20ng/ml and between 20 and 30ng/ml was considered as vitamin D deficiency and insufficiency, respectively. Methods: Relevant observational studies evaluating the prevalence of vitamin D deficiency through 1 January 1990 to 28 Dec 2016, were searched in several electronic databases including Iran-Medex, Scientific Information Database (SID), Irandoc, PubMed and NLM Gateway (for MEDLINE), Web of Science, and Scopus with no restriction on language. Only full-text articles were used for data extraction and synthesis after considering the inclusion/exclusion criteria. Results: 11 studies included; the data of four studies of Iranian newborns were withdrawn because of their high heterogeneity. The prevalence of vitamin D deficiency in Iranian boys and girls were 35% (CI 95% 34-37) and 61% (CI 95% 60-63), respectively. The prevalence of vitamin D insufficiency in Iranian children and adolescents was 31% (CI 95% 30-31). Conclusion: It seems that the prevalence of vitamin D deficiency is very high among Iranian children and adolescents. The present findings could provide practical information for healthcare decision makers.

Vitamin D in the Middle East and North Africa

PURPOSE

The Middle East and North Africa (MENA) region registers some of the lowest serum 25‑hydroxyvitamin D [25(OH)D] concentrations, worldwide. We describe the prevalence and the risk factors for hypovitaminosis D, completed and ongoing clinical trials, and available guidelines for vitamin D supplementation in this region.

METHODS

This review is an update of previous reviews published by our group in 2013 for observational studies, and in 2015 for randomized controlled trials (RCTs) from the region. We conducted a comprehensive search in Medline, PubMed, and Embase, and the Cochrane Library, using MeSH terms and keywords relevant to vitamin D, vitamin D deficiency, and the MENA region, for the period 2012-2017 for observational studies, and 2015-2017 for RCTs. We included large cross-sectional studies with at least 100 subjects/study, and RCTs with at least 50 participants per arm.

RESULTS

We identified 41 observational studies. The prevalence of hypovitaminosis D, defined as a 25‑hydroxyvitamin D [25(OH)D] level below the desirable level of 20 ng/ml, ranged between 12-96% in children and adolescents, and 54-90% in pregnant women. In adults, it ranged between 44 and 96%, and the mean 25(OH)D varied between 11 and 20 ng/ml. In general, significant predictors of low 25(OH)D levels were female gender, increasing age and body mass index, veiling, winter season, use of sun screens, lower socioeconomic status, and higher latitude.We retrieved 14 RCTs comparing supplementation to control or placebo, published during the period 2015-2017: 2 in children, 8 in adults, and 4 in pregnant women. In children and adolescents, a vitamin D dose of 1000-2000 IU/d was needed to maintain serum 25(OH)D level at target. In adults and pregnant women, the increment in 25(OH)D level was inversely proportional to the dose, ranging between 0.9 and 3 ng/ml per 100 IU/d for doses ≤2000 IU/d, and between 0.1 and 0.6 ng/ml per 100 IU/d for doses ≥3000 IU/d. While the effect of vitamin D supplementation on glycemic indices is still controversial in adults, vitamin D supplementation may be protective against gestational diabetes mellitus in pregnant women. In the only identified study in the elderly, there was no significant difference between 600 IU/day and 3750 IU/day doses on bone mineral density. We did not identify any fracture studies.The available vitamin D guidelines in the region are based on expert opinion, with recommended doses between 400 and 2000 IU/d, depending on the age category, and country.

CONCLUSION

Hypovitaminosis D is prevalent in the MENA region, and doses of 1000-2000 IU/d may be necessary to reach a desirable 25(OH)D level of 20 ng/ml. Studies assessing the effect of such doses of vitamin D on major outcomes, and confirming their long term safety, are needed.

Association between serum concentration of 25-hydroxyvitamin D and community-acquired pneumonia: a case-control study

Background

Community-acquired pneumonia (CAP) is a common disease with significant morbidity and mortality. There is evidence that vitamin D deficiency can be associated with infectious diseases. The aim of this study was to compare the levels of vitamin D between patients with CAP and healthy controls.

Methods

In a case-control study on 73 patients with CAP and 76 healthy controls, the serum concentration of 25-hydroxyvitamin D (25[OH]D) was measured. Severity and outcomes of disease and also duration of hospital stay were compared in patients with different levels of 25(OH)D. The severity of CAP was assessed using the CURB-65 score (confusion, uremia, respiratory rate, low blood pressure, age ≥65 years) and was also reflected by the length of hospital stay, admission to intensive care unit (ICU), and 30-day mortality.

Results

In total, 81.2% of the study population had vitamin D levels <30 ng/dL. The risk of pneumonia among subjects with deficient vitamin D levels was 3.69 (95% CI: 1.46, 9.31) times of those with sufficient vitamin D level (P=0.006). Prevalence of severe deficiency of vitamin D in scores three and four of CURB-65 (59.38%), was far more than scores one and two (31.71%). Also, results indicated patients with severe deficiency had a higher risk for ICU admission, 30-day mortality, and longer hospitalization stay, but these were not statistically significant.

Conclusion

According to findings, a low level of 25(OH)D is associated with a higher incidence of CAP and more severe disease. It is recommended to pay more attention to vitamin D deficiency in infectious diseases, particularly in CAP patients.

Correlation of Vitamin D status and orthodontic-induced external apical root resorption

Background

Adequate Vitamin D is essential for dental and skeletal health in children and adult. The purpose of this study was to assess the correlation of serum Vitamin D level with external-induced apical root resorption (EARR) following fixed orthodontic treatment.

Materials and Methods

In this cross-sectional study, the prevalence of Vitamin D deficiency (defined by25-hydroxyvitamin-D) was determined in 34 patients (23.5% male; age range 12-23 years; mean age 16.63 ± 2.84) treated with fixed orthodontic treatment. Root resorption of four maxillary incisors was measured using before and after periapical radiographs (136 measured teeth) by means of a design-to-purpose software to optimize data collection. Teeth with a maximum percentage of root resorption (%EARR) were indicated as representative root resorption for each patient. A multiple linear regression model and Pearson correlation coefficient were used to assess the association of Vitamin D status and observed EARR. P < 0.05 was considered statistically significant.

Results

The Pearson coefficient between these two variables was determined about 0.15 (P = 0.38). Regression analysis revealed that Vitamin D status of the patients demonstrated no significant statistical correlation with EARR, after adjustment of confounding variables using linear regression model (P > 0.05).

Conclusion

This study suggests that Vitamin D level is not among the clinical variables that are potential contributors for EARR. The prevalence of Vitamin D deficiency does not differ in patients with higher EARR. These data suggest the possibility that Vitamin D insufficiency may not contribute to the development of more apical root resorption although this remains to be confirmed by further longitudinal cohort studies.

Comparison of Vitamin D Levels in Naive, Treated, and Inactive Carriers with Chronic Hepatitis B Virus

Background and Aims: During recent years, the relationship between vitamin D levels and chronic hepatitis B (CHB) infection has attracted many researchers' attention. However, the results relating to the association of vitamin D levels and HBV infection have been conflicting and there remains a lack of knowledge about the effects of antiviral treatments on vitamin D level. Methods: Eighty-four patients with CHB were assessed and divided into three groups: inactive carriers (n = 28), treated (n = 34), and new (treatment-naïve) cases (n = 22). Thirty-two healthy controls (HCs) were included to enable comparison with the CHB groups. The levels of vitamin D3 were measured and statistically compared among the various groups. Results: Male subjects had higher levels of vitamin D3 (41.25 vs 28.85, p < 0.01). No association was found among any of the groups when compared with the HC group. Despite the significant association, the HCs demonstrated a higher level of vitamin D3, which was lower in the treated group, the inactive carrier group, and the new cases group (new case [29.82] < inactive carrier [32.91] < treated [39.56] < control [44.88]). The HBV DNA levels were not associated with vitamin D3 levels in the inactive carriers (p = 0.171), the treated groups (p = 0.192), and the new cases (p = 0.369). Moreover, the alanine transaminase and aspartate transaminase levels were not associated with vitamin D3 levels for any of the HBV-infected groups. Conclusions: Vitamin D3 contributes to the clinical statues of CHB patients. There is also a possible correlation between clinically healthy CHB patients and vitamin D3 level.

Effects of Vitamin D on Endometriosis-Related Pain: A Double-Blind Clinical Trial

BACKGROUND Endometriosis is a disabling disease of reproductive-age women. Dysmenorrhea, dyspareunia, and pelvic pain are the main symptoms of endometriosis. Its etiology is not clear. Endometriosis may have various causes, including vitamin D deficiency, but its effect is controversial. MATERIAL AND METHODS In this double-blind clinical trial, we enrolled patients with endometriosis diagnosed and treated by laparoscopy, with scores of at least 3 for of dysmenorrhea and/or pelvic pain at 8 weeks after surgical treatment. They were randomly prescribed vitamin D (50 000 IU weekly for 12 weeks) or placebo. Severity of pain in the 2 groups (placebo and treatment) was compared by VAS test at 24 weeks after surgical treatment. RESULTS There were 19 patients in the vitamin D group and 20 in the placebo group. Baseline characteristics in the 2 groups were similar. Following the treatment with vitamin D or placebo, we did not find significant differences in severity of pelvic pain (p=0.24) and dysmenorrhea (p=0.45) between the 2 groups. Mean pelvic pain at 24 weeks after laparoscopy in the vitamin D group was 0.84±1.74 and in placebo group it was 0.68±1.70 (p=0.513). Mean dysmenorrhea was 2.10±2.33 in the vitamin D group and 2.73±2.84 in the placebo group (p=0.45). CONCLUSIONS After ablative surgery for endometriosis, vitamin D treatment did not have a significant effect in reducing dysmenorrhea and/or pelvic pain.

Vitamin D deficiency and its impact on asthma severity in asthmatic children

BACKGROUND

Despite obtaining evidences on association between vitamin D and development of lung in fetus, little is known about vitamin D level and its impact on severity of asthma in children. The present study aimed to assess the relationship between the asthma severity and vitamin D deficiency in asthmatic children.

METHODS

This case-control study was conducted on 106 individuals including asthmatic (n = 53) and healthy children (n = 53) who referred to Mofid hospital in Tehran in 2013. The level of serum vitamin D in both groups was measured by radioimmunoassay method at the reference lab and was categorized as sufficient (> 30 ng/ml), insufficient (20 to 30 ng/ml), or deficient (< 20 ng/ml). The control status of asthma in patients group was classified as controlled, partially controlled, and uncontrolled.

RESULTS

In the groups with and without asthma, the prevalence of vitamin D deficiency was 73.6 and 49.1%, and the prevalence of vitamin D insufficiency was 18.9 and 18.9%, while normal vitamin D level was revealed in 7.5 and 32.1%, respectively with a significant difference (p = 0.005). Using the multivariate logistic regression analysis, the presence of asthma was associated with reduced level of vitamin D (OR = 1.068, 95% CI: 1.027-1.110, P = 0.001). In this context, the risk for asthma in the children with vitamin D deficiency was 6.3 times of those with normal vitamin D level. Although the presence of asthma was strongly associated with reduced level of vitamin D in serum, neither severity of asthma nor control status of asthma were associated with vitamin D deficiency.

CONCLUSION

The presence of vitamin D deficiency effectively predict increased risk for childhood asthma; however the severity or control status of this event may not be predicted by confirming vitamin D deficiency.

A Survey of Vitamin D Status in Patients with Degenerative Diseases of the Spine

STUDY DESIGN

Descriptive cross-sectional study.

PURPOSE

To determine the prevalence of vitamin D deficiency in patients with degenerative diseases of the spine about to undergo spinal surgery and the relations between such deficiency and potential risk factors.

OVERVIEW OF LITERATURE

Vitamin D has a major role in musculoskeletal system health maintenance. Recently, studies on degenerative diseases of the spine have shown a high prevalence of vitamin D deficiency in patients undergoing spine surgery.

METHODS

Serum levels of 25(OH)D were determined by an electrochemiluminescence detection assay. The other variables were determined through relevant questionnaires, and the data was analyzed through analysis of variance, t-test, chi-square and multivariate logistic regression analysis.

RESULTS

A total of 110 patients were enrolled in the study. The mean serum level of 25(OH)D was 27.45±18.75 ng/mL, and 44.5% of patients showed vitamin D deficiency (25(OH)D<20 ng/mL), with an additional 17.3% of patients having a serum level of 25(OH)D that was insufficient (20≤25(OH)D<30 ng/mL). The prevalence of vitamin D deficiency was significantly higher in the younger age group compared to the older age group (p<0.001) and the ones without a history of taking vitamin D supplements (p=0.013). Compared to men, women showed significantly higher levels of vitamin D (p=0.029).

CONCLUSIONS

A high prevalence of vitamin D deficiency is seen in patients with degenerative diseases of the spine. On the other hand, the conventional risk factors such as old age or female sex alone did not seem to be sufficient in determining the likelihood of deficiency. Thus, it is recommended that vitamin D deficiency prevention strategies comprise a broader spectrum of the population through which such degenerative diseases and their consequences may be prevented or delayed.

Serum C3 epimer of 25-hydroxyvitamin D and its determinants in adults: a national health examination survey in Thais

A high percentage have detectable C3 epimer of 25-hydroxyvitamin D3 (3-epi-25(OH)D3) in the population of Thai National Health Examination Survey IV.

INTRODUCTION

C3 epimers of vitamin D have recently been shown to contribute significantly to 25-hydroxyvitamin D (25(OH)D) levels in an infant population. However, the findings in the general adult population are unclear. Therefore, the purpose of the present study is to determine the percentage of the C3 epimer of 25(OH)D (3-epi-25(OH)D) and its determinants in an adult population.

METHODS

A subsample of 1148 sera randomly selected from the Thai National Health Examination Survey IV (2009) samples were measured for serum 25(OH)D2, 25(OH)D3, 3-epi-25(OH)D2, and 3-epi-25(OH)D3 by LC-MS/MS method. The relative 3-epimer contribution (%) was used to express the amount of 3-epimer-25(OH)D3 as a percentage of total 25(OH)D3 (the sum of 25(OH)D3, and 3-epi-25(OH)D3).

RESULTS

A high proportion of subjects had detectable 3-epi-25(OH)D3 that was <10 % of the total 25(OH)D levels. Since the level of total 25(OH)D2 is low, only a minority of subjects had detectable 3-epi-25(OH)D2. Multivariate analysis suggested that age, male gender, and rural residence were independently related to the 3-epi-25(OH)D3/total 25(OH)D3 ratio.

CONCLUSIONS

A high percentage of Thai adults had detectable 3-epi-25(OH)D3 that was <10 % of the total 25(OH)D levels. Age, gender, and living in a rural area were associated with the relative amount of 3-epi-25(OH)D3 to total 25(OH)D3.

The prevalence of vitamin D deficiency among schoolchildren: a cohort study from Xinxiang, China

AIM

Vitamin D deficiency (VDD) in children is widespread. Therefore, the present study was conducted to assess the prevalence of VDD in schoolchildren from Henan Province, China.

METHODS

The study was conducted on school students from areas of Xinxiang, one of the largest cities of Henan Province in China, in the winter of 2013. A questionnaire on demographic data, socioeconomic status, sun exposure, and times of acute respiratory infections (RTI) in the past 12 months were completed for each student. Blood samples were taken to assess serum levels of 25-hydroxyvitamin D [25(OH)D].

RESULTS

In our study, 606 schoolchildren completed the questionnaire. The median serum level of 25(OH)D was 20.5 ng/mL (interquartile range: 15.9-25.1). The prevalence of VDD and insufficiency was 46.9% (284/606) and 85.8% (520/606), respectively. VDD was more associated with female gender, high body mass index, lower socio-professional status, residence in urban areas, and less time spent outdoors. There was an inverse correlation between levels of 25(OH) and times of RTI (p<0.001).

CONCLUSION

VDD and insufficiency are common among schoolchildren in Xinxiang. Supplementation with food fortification or vitamin D for Chinese children is warranted.