Predicting vitamin D deficiency in older Australian adults

An Adapted Questionnaire Tailored for Assessing the Risk of Vitamin D Deficiency in Children That Is Proving Useful in Guiding Clinical Interventions

BACKGROUND

The identification of vitamin D (VitD) deficiency in pediatric populations is essential for preventive healthcare. We refined and tested the Evaluation of Deficiency Questionnaire (EVIDENCe-Q) for its utility in detecting VitD insufficiency among children.

PATIENTS AND METHODS

We enrolled 201 pediatric patients (aged between 3 and 18 years). Clinical evaluation and serum vitamin D levels were assessed in all subjects. The EVIDENCe-Q was updated to incorporate factors influencing VitD biosynthesis, intake, assimilation, and metabolism, with scores spanning from 0 (optimal) to 36 (poor).

RESULTS

We established scores for severe deficiency (<10 mg/dL) at 20, deficiency (<20 mg/dL) at 22, and insufficiency (<30 mg/dL) at 28. A score of 20 or greater was determined as the optimal cut-off for distinguishing VitD deficient from sufficient statuses, as evidenced by ROC curve analysis AUC = 0.7066; SE = 0.0841; sensitivity 100%, 95% CI 0.561-1. The most accurate alignment was seen with VitD insufficiency, defined as 25-OH-D3 < 20 ng/mL.

CONCLUSIONS

This study confirms that the EVIDENCe-Q is a valid instrument for assessing the risk of vitamin D deficiency and insufficiency in children. It offers a practical approach for determining the need for clinical intervention and dietary supplementation of VitD in the pediatric population.

Development and Validation of a Predictive Model of Hypovitaminosis D in General Adult Population: SCOPYD Study

The worldwide global increase in serum 25-hydroxyvitamin D (25(OH)D) measurements has led some countries to restrict reimbursement for certain clinical situations only. Another approach could consist in providing physicians with screening tools in order to better target blood test prescription. The objective of the SCOPYD study was to identify the best combination of predictors of serum VitD concentration among adults aged 18–70 years. Potential risk factors for VitD deficiency were collected using a comprehensive self-administered questionnaire. A multivariable linear regression was used to build a predictive model of serum 25(OH)D concentration. Among 2488 participants, 1080 (43.4%) had VitD deficiency (<50 nmol/L) and 195 (7.8%) had severe deficiency (<25 nmol/L). The final model included sunlight exposure in the preceding week and during the last holidays, month of blood sampling, age, sex, body mass index, skin phototype, employment, smoking, sport practice, latitude, and VitD supplementation in preceding year. The area under the curve was 0.82 (95% CI (0.78; 0.85)) for severe deficiency. The model predicted severe deficiency with a sensitivity of 77.9% (95% CI (69.1; 85.7)) and a specificity of 68.3% (95% CI (64.8; 71.9)). We identified a set of predictors of severe VitD deficiency that are easy to collect in routine that may help to better target patients for serum 25(OH)D concentration determination.

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.

Prediction models and questionnaires developed to predict vitamin D status in adults: a systematic review

A systematic review of prediction models/questionnaires developed to identify people with deficient/insufficient vitamin D status shows the potential of self-reported information to estimate vitamin D status. The objective is to identify and compare existing screening tools, developed to identify vitamin D deficiency or insufficiency in adults. A systematic search of literature was conducted using MEDLINE, Scopus, Web of Science and CINAHL databases. Risk of bias and applicability concerns were assessed by quality assessment of diagnostic accuracy studies (QUADAS-2). Data were extracted on socio-demographic, anthropometric, risk factors, serum 25 hydroxyvitamin D [25(OH)D] levels, statistical methods and predictive ability. A total of 12 studies were considered for inclusion for this systematic review after screening of 4851 abstracts and 15 full-text articles. Ten of twelve studies developed prediction models and 2 studies developed questionnaires. The majority of studies had low risk of bias and applicability as assessed by QUADAS-2. All studies included only self-reported predictors of vitamin D status in their final models and development of scores. Sunlight exposure and related factors were important significant contributors to the predictive ability of the models and/or questionnaires. Sensitivity and specificity of the prediction models or questionnaires ranged from 55 to 91% and 35 to 84%, respectively. Six out of twelve studies converted final models to scores associated with vitamin D status. There was no evidence that any of these existing tools have been translated into clinical practice. The prediction models or questionnaires identified in this systematic review were moderately sensitive and specific for identifying people with vitamin D deficiency or insufficiency. The substantial contribution of sunlight exposure to the prediction of vitamin D status highlights the importance of including this information when developing vitamin D screening tools.

A randomized placebo-controlled trial of vitamin D supplementation for reduction of mortality and cancer: Statistical analysis plan for the D-Health Trial

Background

Many observational studies have reported an association between vitamin D and non-skeletal health outcomes. The D-Health Trial was launched to determine if supplementing the older population with high monthly doses of Vitamin D can prevent cancer and premature mortality. The intervention is ongoing but here we provide a detailed statistical analysis plan for the primary and secondary outcomes of the D-Health Trial.

Methods/design

The D-Health Trial is a double-blind, randomized, placebo-controlled trial. Between February 2014 and May 2015, 21,315 people were randomized in a 1:1 ratio to receive monthly doses of either 60,000 IU of cholecalciferol (vitamin D₃) or placebo for five years. The primary outcome is all-cause mortality and the secondary outcomes are total cancer incidence and colorectal cancer incidence. These will be ascertained via linkage to death and cancer registries. The primary analysis for each outcome will follow an intention-to-treat approach; we will use flexible parametric survival models to investigate the association between supplementation and time to an event. We describe in detail sophisticated secondary analyses that consider non-compliance and contamination due to off-study supplementation.

Conclusions

Publication of this statistical analysis plan in advance of the intervention's completion, and adherence to it, will avoid data-driven analyses of the primary and secondary outcomes and ensure robust reporting of outcomes.

Clinical trial registration number

Australian New Zealand Clinical Trials Registry: ACTRN12613000743763. Registered on 4 July 2013.

Prediction of insufficient serum vitamin D status in older women: a validated model

We developed an externally validated simple prediction model to predict serum 25(OH)D levels < 30, < 40, < 50 and 60 nmol/L in older women with risk factors for fractures. The benefit of the model reduces when a higher 25(OH)D threshold is chosen.

INTRODUCTION

Vitamin D deficiency is associated with increased fracture risk in older persons. General supplementation of all older women with vitamin D could cause medicalization and costs. We developed a clinical model to identify insufficient serum 25-hydroxyvitamin D (25(OH)D) status in older women at risk for fractures.

METHODS

In a sample of 2689 women ≥ 65 years selected from general practices, with at least one risk factor for fractures, a questionnaire was administered and serum 25(OH)D was measured. Multivariable logistic regression models with backward selection were developed to select predictors for insufficient serum 25(OH)D status, using separate thresholds 30, 40, 50 and 60 nmol/L. Internal and external model validations were performed.

RESULTS

Predictors in the models were as follows: age, BMI, vitamin D supplementation, multivitamin supplementation, calcium supplementation, daily use of margarine, fatty fish ≥ 2×/week, ≥ 1 hours/day outdoors in summer, season of blood sampling, the use of a walking aid and smoking. The AUC was 0.77 for the model using a 30 nmol/L threshold and decreased in the models with higher thresholds to 0.72 for 60 nmol/L. We demonstrate that the model can help to distinguish patients with or without insufficient serum 25(OH)D levels at thresholds of 30 and 40 nmol/L, but not when a threshold of 50 nmol/L is demanded.

CONCLUSIONS

This externally validated model can predict the presence of vitamin D insufficiency in women at risk for fractures. The potential clinical benefit of this tool is highly dependent of the chosen 25(OH)D threshold and decreases when a higher threshold is used.

Association between serum 25-hidroxyvitamin D concentrations and ultraviolet index in Portuguese older adults: a cross-sectional study

Background

The older population is a risk group for hypovitaminosis D. The Ultraviolet Index (UVI) can be an indicator of potential for cutaneous synthesis of vitamin D but physiological and other environmental factors also influence vitamin D synthesis and status. Knowledge about vitamin D status in Portuguese older adults is limited. This study aims to explore the association between Ultraviolet Index and serum 25-hidroxyvitamin D3 [25(OH)D] levels accounting for other potential influential factors.

Methods

A cross-sectional study was conducted between December 2015 and June 2016, in 1497 Portuguese older adults (≥ 65 years) within Nutrition UP 65 project. For each participant, serum 25(OH)D was determined and the mean UVI (mUVI) in the respective residence district was calculated for the previous 30 days. Stepwise linear regression analyses were conducted for the following periods of blood collection: between December and June, December and March and April and June. Standardized regression coefficients (Sβ) and 95% confidence intervals were calculated.

Results

The median 25(OH)D concentration was 35.9 nmol/L. The UVI was independently and positively associated with 25(OH)D in the models for December–June (Sβ = 0.244, 95% CI: 0.198; 0.291, P < 0.001) and April–June (Sβ = 0.295, 95% CI: 0.299; 0.362, P < 0.001) and independently and negatively associated in December–March period (Sβ = −0.149, 95% CI: -0.211; −0.087, P < 0.001).

Conclusions

In this sample with high vitamin D deficiency frequency, the UVI was a predictor of 25(OH)D levels but the direction of the association varied according to the blood collection period. Our results suggest that accounting for the time of year in future research regarding vitamin status and related public health recommendations may be relevant.

Electronic supplementary material

The online version of this article (10.1186/s12877-017-0644-8) contains supplementary material, which is available to authorized users.

Vitamin D status among the elderly Chinese population: a cross-sectional analysis of the 2010-2013 China national nutrition and health survey (CNNHS)

BACKGROUND

Vitamin D inadequacy is common among the elderly, especially within the Asian population. The vitamin D status among healthy adults in the elderly Chinese population was evaluated.

METHODS

A total of 6014 healthy adults aged 60 years or older (2948 men, 3066 women) participated in this descriptive cross-sectional analysis. Possible predictors of vitamin D inadequacy were evaluated via multiple logistic regression analyses.

RESULTS

The median serum 25-hydroxyvitamin D (25(OH)D) levels were 61.0 nmol/l (interquartile range (IQR) 44.3-80.6, range 5.1-154.5) for men and 53.7 nmol/l (IQR 38.8-71.0, range 6.0-190.0) for women, with 34.1% (95% confidence interval (CI) 32.4-35.8) of men and 44.0% (95% CI 42.2-45.8) of women presenting vitamin D inadequacy (25(OH)D <50 nmol/l). According to the multivariate logistic regression analyses, vitamin D inadequacy was positively correlated with female gender (P <0.0001), underweight (P = 0.0259), the spring season (P <0.0001), low ambient UVB levels (P <0.0001) and living in large cities (P = 0.0026). For men, vitamin D inadequacy was positively correlated with the spring season (P = 0.0015), low ambient UVB levels (P <0.0001) and living in large cities (P = 0.0022); for women, vitamin D inadequacy was positively correlated with the spring season (P = 0.0005) and low ambient UVB levels (P <.0001).

CONCLUSIONS

Vitamin D inadequacy is prevalent among the elderly population in China. Because residing in regions with low ambient UVB levels increases the risk of vitamin D inadequacy both for men and women, vitamin D supplementation and sensible sun exposure should be encouraged, especially during the cooler seasons. Further studies are required to determine the optimal vitamin D intake and sun exposure levels to maintain sufficient vitamin D levels in the elderly Chinese population.

Prevailing vitamin D status influences mitochondrial and glycolytic bioenergetics in peripheral blood mononuclear cells obtained from adults

BACKGROUND

Circulating peripheral blood mononuclear cells (PBMCs) are exposed to metabolic and immunological stimuli that influence their functionality. We hypothesized that prevailing vitamin D status [25(OH)D] would modulate the bioenergetic profile of PBMCs derived from humans.

MATERIALS AND METHODS

38 participants (16 males, 22 females) ranging in body fat from 14-51% were studied. PBMCs were isolated from whole blood, counted and freshly seeded for bioenergetic analysis using the Seahorse XF^e96 flux analyser. Whole body energy metabolism via indirect calorimetry, body composition by dual-energy X-ray absorptiometry, and relevant clinical biochemistry were measured. Data was analysed based on 25(OH)D cut-offs of <50nmol/L (Group 1, n=12), 50-75nmol/L (Group 2, n=15) and ≥75nmol/L (Group 3, n=11). A multivariate general linear model adjusting for age, fat mass, fat-free mass, parathyroid hormone and insulin sensitivity was used.

RESULTS

There were significant differences in cellular mitochondrial function between groups. Group 1 had significantly higher basal respiration (p=0.001), non-mitochondrial respiration (p=0.009), ATP production (p=0.001), proton leak (p=0.018), background glycolysis (p=0.023) and glycolytic reserve (p=0.039) relative to either Group 2 or Group 3; the latter two did not differ on any measures. There were no differences in bioenergetic health index (BHI), resting metabolic rates and systemic inflammatory markers between groups.

CONCLUSIONS

Inadequate vitamin D status adversely influenced bioenergetic parameters of PBMCs obtained from adults, in a pattern consistent with increased oxidative metabolism and activation of these cells.

Quick and Easy Screening for Vitamin D Insufficiency in Adults: A Scoring System to Be Implemented in Daily Clinical Practice

Vitamin D is essential regarding several health outcomes. Prevention of insufficiency (25-hydroxyvitamin D concentration ≤20 ng/mL) generally entails blood testing and/or supplementation, strategies that should target at-risk individuals because blood testing is costly, and unwarranted supplementation could result in vitamin D overload with unknown long-term consequences. Our objective was to develop a simple score (Vitamin D Insufficiency Prediction score, VDIP) for identifying adults at risk of vitamin D insufficiency. Subjects were 1557 non-vitamin D-supplemented middle-aged adults from the SU.VI.MAX cohort. Scoring points corresponded to the rounded odds ratio for each individual-level characteristic associated with vitamin D insufficiency in a multivariable logistic regression model. Receiver operating characteristic curve (area under curve), sensitivity, specificity, and positive and negative predictive values were computed. External validation was performed in an independent cohort (NutriNet-Santé, N = 781). For female sex, overweight, low physical activity, winter season, moderate sun exposure, and very fair or dark skin 1.5 points were attributed; 2 points for latitude ≥48°N and spring season; 2.5 points for obesity and late winter; 3 points for low sun exposure. Points were then summed up for each participant. The VDIP score had an AUC = 0.70 ± 0.01 (validation: 0.67 ± 0.02). With a score of 7 or more, 70% of the participants were vitamin D-insufficient (80% in those with a score ≥9), sensitivity/specificity were 0.67/0.63, and positive and negative predictive values were 0.70/0.59. The VDIP score performed well in identifying middle-aged adults at risk of vitamin D insufficiency (score ≥7, moderate risk; score≥9, high risk), using only simple individual-level characteristics easily assessable in day-to-day clinical practice. Implementation of this simple and costless score could thus obviate unwarranted supplementation and/or blood testing.

The Impact of Vitamin D Levels on Inflammatory Status: A Systematic Review of Immune Cell Studies

Chronic low-grade inflammation accompanies obesity and its related chronic conditions. Both peripheral blood mononuclear cells (PBMCs) and cell lines have been used to study whether vitamin D has immune modulating effects; however, to date a detailed systematic review describing the published evidence has not been completed. We therefore conducted a systematic review on the effect of vitamin D on the protein expression and secretion of inflammatory markers by human-derived immune cells. The review was registered at the International Prospective Register for Systematic Reviews (PROSPERO, Registration number CRD42015023222). A literature search was conducted using Pubmed, Science Direct, Scopus, Web of Science and Medline. The search strategy used the following search terms: Vitamin D or cholecalciferol or 1,25-dihydroxyvitamin or 25-hydroxy-Vitamin D and Inflam* or cytokine* and supplement* or cell*. These terms were searched in the abstract, title and keywords. Inclusion criteria for study selection consisted of human-derived immune cell lines or cellular studies where PBMCs were obtained from humans, reported in the English language, and within the time period of 2000 to 2015. The selection protocol was mapped according to PRISMA guidelines. Twenty three studies (7 cell line and 16 PBMCs studies) met our criteria. All studies selected except one used the active metabolite 1,25(OH)2, with one study using cholecalciferol and two studies also using 25(OH)D. Four out of seven cell line studies showed an anti-inflammatory effect where suppression of key markers such as macrophage chemotactic protein 1, interleukin 6 and interleukin 8 were observed. Fourteen of sixteen PBMC studies also showed a similar anti-inflammatory effect based on common inflammatory endpoints. Mechanisms for such effects included decreased protein expression of toll-like receptor-2 and toll-like receptor-4; lower levels of phosphorylated p38 and p42/42; reduced expression of phosphorylated signal transducer and activator of transcription 5 and decreased reactive oxygen species. This review demonstrates that an anti-inflammatory effect of vitamin D is a consistent observation in studies of cell lines and human derived PBMCs.

Sex-specific determinants of serum 25-hydroxyvitamin D3 concentrations in an elderly German cohort: a cross-sectional study

Background

Considering the suggested link between vitamin D insufficiency and several chronic diseases, attention should be given to approaches for improving vitamin D status. Elderly subjects are regarded as a high-risk group for developing an insufficient vitamin D status. Socioeconomic, dietary, lifestyle and environmental factors are considered as influencing factors, whereupon sex differences in predictors of vitamin D status are rarely investigated. The purpose of this study is to identify the main predictors of serum 25-hydroxyvitamin D₃ [25(OH)D₃] concentrations in elderly subjects by taking into account potential sex differences.

Methods

This is a cross-sectional study in 162 independently living German elderly aged 66 to 96 years. Serum 25(OH)D₃ concentrations were assessed by an electrochemiluminescence immunoassay. Multiple regression analyses were performed to identify predictors of 25(OH)D₃ concentrations stratified by sex.

Results

Median 25(OH)D₃ concentration was 64 nmol/L and none of the subjects had 25(OH)D₃ concentrations < 25 nmol/L. In women, intact parathyroid hormone (iPTH) (β = -0.323), % total body fat (β = -0.208), time spent outdoors (β = 0.328), month of blood sampling (β = 0.229) and intake of vitamin D supplements (β = 0.172) were the predominant predictors of 25(OH)D₃, whereas in men, iPTH (β = -0.254), smoking (β = -0.282), physical activity (β = 0.336) and monthly household net income (β = 0.302) predicted 25(OH)D₃ concentrations. The final regression models accounted for 30% and 32% of the variance in 25(OH)D₃ concentrations in women and men, respectively.

Conclusion

The findings indicate that 25(OH)D₃ concentrations are influenced by body composition, month of blood sampling, economic factors, lifestyle, supplement intake and iPTH, but may not be associated with age, sex, dietary factors, kidney function and presence of selected chronic diseases in community-dwelling elderly. Furthermore, our results provide evidence for sex-specific determinants of the vitamin D status, which ought to be considered for preventive strategies.

Association between ultraviolet radiation, skin sun sensitivity and risk of pancreatic cancer

BACKGROUND

Ecological studies showing an inverse association between pancreatic cancer incidence and mortality and levels of ultraviolet radiation (UVR), suggest that higher levels of sun exposure may reduce risks of pancreatic cancer but there has been only one individual-level study that examined this issue. We aimed to examine the association between pancreatic cancer and markers of exposure to solar UVR, namely skin type, treatment of skin lesions, ambient UVR and time outdoors on work days.

METHODS

We used data from an Australian case-control study. Location at birth, residential location during adulthood, outdoors work, history of skin lesion treatment and sensitivity of the skin to the sun were obtained by questionnaire. We limited the analyses to Caucasians who answered the questionnaire about UVR (controls=589/711 recruited; cases=496/705 recruited). We used NASA's Total Ozone Mapping Spectrometer to estimate ambient UVR.

RESULTS

Being born in or living in areas of higher ambient UVR (compared to lower ambient UVR) was associated with about 30-40% lower risk of pancreatic cancer. People with fair skin colour had 47% lower risk of pancreatic cancer than those with dark skin colour (95% CI 0.37-0.75). There was some suggestion of increased risk with increased average number of hours spent outside at work.

CONCLUSIONS

This study suggests that people with light skin colour or those born or living in areas of high ambient UVR have lower risk of pancreatic cancer. Our analysis supports an association between UVR and pancreatic cancer, possibly mediated through production of vitamin D.