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Background/ObjectivesVitamin D deficiency is a public health concern worldwide. Maintaining vitamin D sufficiency during growth periods is essential. We aimed to determine the prevalence and predictors of vitamin D deficiency in Australian adolescents and young adults.Subject/MethodsWe used data from adolescents (12–17 years, n = 692) and young adults (18–24 years, n = 400) who participated in the nationally representative 2011–2013 Australian Health Survey. Serum 25-hydroxyvitamin D concentrations were measured using a method certified to international standards, with prevalence reported for <50 (vitamin D deficiency), 50–<75, ≥75 and >125 nmol/L. Independent predictors of vitamin D deficiency were determined using a survey-weighted Poisson regression model.ResultsOverall, 17% of adolescents and 32% of young adults were vitamin D deficient. In models adjusted for sex, age, region of birth, socioeconomic status, BMI and season (and education, smoking status and physical activity in young adults only), the prevalence ratio (PR) for vitamin D deficiency was more than double in participants born outside Australia (adolescents: PR 2.46; 95% confidence interval (CI) = 1.59, 3.81; young adults: PR 2.12; 95% CI = 1.46, 3.07), and also varied by season (adolescents: spring vs summer PR 2.47; 95% CI = 1.22, 5.01 and winter vs summer PR 2.01; 95% CI = 1.03, 3.92; young adults: winter vs summer; PR 3.32; 95% CI = 1.69, 6.53). Other predictors of vitamin D deficiency were overweight compared with healthy weight (adolescents) and lower physical activity (young adults).ConclusionsStrategies based on safe sun exposure and dietary approaches are needed to achieve and maintain adequate vitamin D status, particularly in young adults.

Myopia (near-sightedness) is an important public health issue. Spending more time outdoors can prevent myopia but the long-term association between this exposure and myopia has not been well characterised. We investigated the relationship between time spent outdoors in childhood, adolescence and young adulthood and risk of myopia in young adulthood. The Kidskin Young Adult Myopia Study (KYAMS) was a follow-up of the Kidskin Study, a sun exposure-intervention study of 1776 children aged 6–12 years. Myopia status was assessed in 303 (17.6%) KYAMS participants (aged 25–30 years) and several subjective and objective measures of time spent outdoors were collected in childhood (8–12 years) and adulthood. Index measures of total, childhood and recent time spent outdoors were developed using confirmatory factor analysis. Logistic regression was used to assess the association between a 0.1-unit change in the time outdoor indices and risk of myopia after adjusting for sex, education, outdoor occupation, parental myopia, parental education, ancestry and Kidskin Study intervention group. Spending more time outdoors during childhood was associated with reduced risk of myopia in young adulthood (multivariable odds ratio [OR] 0.82, 95% confidence interval [CI] 0.69, 0.98). Spending more time outdoors in later adolescence and young adulthood was associated with reduced risk of late-onset myopia (≥ 15 years of age, multivariable OR 0.79, 95% CI 0.64, 0.98). Spending more time outdoors in both childhood and adolescence was associated with less myopia in young adulthood.

Improved understanding of the association between tuberculosis and vitamin D is needed to inform clinical practice. Vitamin D has both immunostimulatory and immunosuppressive effects relevant to human antimycobacterial responses. Ultraviolet radiation, the main source of vitamin D, also induces immunomodulation and could affect the relation between vitamin D and tuberculosis. Clinical trials of vitamin D supplementation in patients with tuberculosis have produced largely negative results, prompting the review of dosing regimens—an explanation for low 25-hydroxyvitamin D status in patients with active tuberculosis is also needed. The reporting of vitamin D deficiency needs to address assay inaccuracies, rising thresholds to define sufficiency, and scarce knowledge of the concentrations needed for optimum immune responses. Future research to measure the effect of the inflammatory setting on serum concentrations of 25-hydroxyvitamin D, at tuberculosis diagnosis and during recovery, could help to account for 25-hydroxyvitamin D changes in these concentrations in patients with tuberculosis. Studies into the role of vitamin D supplementation in latent tuberculosis justify clinical trials in this population, but pose methodological challenges. Vitamin D trials in patients with active tuberculosis should be done in well selected populations using adequate vitamin D doses, although such doses remain undefined.

Epidemiological evidence shows that people with thicker, or higher stage, melanomas have lower vitamin D status compared to those with thinner tumours. Evidence from experimental studies is inconsistent, but some suggest that administration of vitamin D metabolites can decrease tumour aggressiveness. Determine the relationship between vitamin D status at diagnosis and melanoma thickness (as an indicator of prognosis), in a subtropical setting with high melanoma incidence. We recruited 100 melanoma patients in Brisbane, Australia within days of their diagnosis. Data on factors previously associated with melanoma risk or prognosis were collected by questionnaire and physical examination. Serum for 25-hydroxyvitamin D3 [25(OH)D] levels was collected prior to wider excision biopsy; histological indicators of prognosis were obtained from pathology reports. We used multivariable logistic regression models to analyse the association between Breslow thickness (≥0.75 mm compared to <0.75 mm), Clark level (2-5 compared to 1) and presence of mitoses, and vitamin D status. Serum 25(OH)D <50 nmol/L (versus ≥50 nmol/L) was associated with a nearly four-fold increase in risk of having a thicker tumour (Adjusted OR = 3.82, 95% CI: 1.03, 14.14; p = 0.04, adjusted for age, sex, skin phototype, body mass index and season at diagnosis). There was no significant association with Clark level or presence of mitosis. Serum 25(OH)D levels in the highest quartile (≥69.8 nmol/L) were not associated with a more favourable prognosis. Vitamin D deficiency at the time of melanoma diagnosis is associated with thicker tumours that are likely to have a poorer prognosis. Ensuring vitamin D levels of 50 nmol/L or higher in this population could potentially result in 18% of melanomas having Breslow thickness of <0.75 mm rather than ≥0.75 mm.

Measured serum 25-hydroxyvitamin D concentrations vary depending on the type of assay used and the specific laboratory undertaking the analysis, impairing the accurate assessment of vitamin D status. We investigated differences in serum 25-hydroxyvitamin D concentrations measured at three laboratories (laboratories A and B using an assay based on liquid chromatography-tandem mass spectrometry and laboratory C using a DiaSorin Liaison assay), against a laboratory using an assay based on liquid chromatography-tandem mass spectrometry that is certified to the standard reference method developed by the National Institute of Standards and Technology and Ghent University (referred to as the 'certified laboratory'). Separate aliquots from the same original serum sample for a subset of 50 participants from the Ausimmune Study were analysed at the four laboratories. Bland-Altman plots were used to visually check agreement between each laboratory against the certified laboratory. Compared with the certified laboratory, serum 25-hydroxyvitamin D concentrations were on average 12.4 nmol/L higher at laboratory A (95% limits of agreement: -17.8,42.6); 12.8 nmol/L higher at laboratory B (95% limits of agreement: 0.8,24.8); and 10.6 nmol/L lower at laboratory C (95% limits of agreement: -48.4,27.1). The prevalence of vitamin D deficiency (defined here as 25-hydroxyvitamin D <50 nmol/L) was 24%, 16%, 12% and 41% at the certified laboratory, and laboratories A, B, and C, respectively. Our results demonstrate considerable differences in the measurement of 25-hydroxyvitamin D concentrations compared with a certified laboratory, even between laboratories using assays based on liquid chromatography-tandem mass spectrometry, which is often considered the gold-standard assay. To ensure accurate and reliable measurement of serum 25-hydroxyvitamin D concentrations, all laboratories should use an accuracy-based quality assurance system and, ideally, comply with international standardisation efforts.

Risk factors for cardiovascular disease (CVD), such as obesity, diabetes, hypertension and physical inactivity, are common in Australia, but the prevalence varies according to cultural background. We examined the relationship between region of birth, measures of acculturation, and CVD risk profiles in immigrant, compared to Australian-born, older Australians. Cross-sectional data from 263,356 participants aged 45 and over joining the population-based 45 and Up Study cohort from 2006-2008 were used. Prevalence ratios for CVD risk factors in Australian- versus overseas-born participants were calculated using modified Poisson regression, adjusting for age, sex and socioeconomic factors and focusing on Asian migrants. The association between time resident in Australia and age at migration and CVD risk factors in Asian migrants was also examined. Migrants from Northeast (n = 3,213) and Southeast Asia (n = 3,942) had lower levels of overweight/obesity, physical activity and female smoking than Australian-born participants (n = 199,356), although differences in prevalence of overweight/obesity were sensitive to body-mass-index cut-offs used. Compared to Australian-born participants, migrants from Northeast Asia were 20-30% less likely, and from Southeast Asia 10-20% more likely, to report being treated for hypertension and/or hypercholesterolaemia; Southeast Asian migrants were 40-60% more likely to report diabetes. Northeast Asian-born individuals were less likely than Australian-born to have 3 or more CVD risk factors. Diabetes, treated hypertension and hypercholesterolaemia occurred at relatively low average body-mass-index in Southeast Asian migrants. The CVD risk factor profiles of migrants tended to approximate those of Australian-born with increasing acculturation, in both favourable (e.g., increased physical activity) and unfavourable directions (e.g., increased female smoking). Minimizing CVD risk in migrant populations may be achieved through efforts to retain the healthy facets of the traditional lifestyle, such as a normal body mass index and low prevalence of smoking in women, in addition to adopting healthy aspects of the host country lifestyle, such as increased physical activity.

Population-level ecological studies show type 1 diabetes incidence is inversely correlated with ambient ultraviolet radiation (UVR) levels. We conducted a nested case–control study using administrative datasets to test this association at the individual level. Cases ( n  = 1819) were children born in Western Australia (WA) from 1980–2014, diagnosed with type 1 diabetes at ≤ 16 years. Controls ( n  = 27,259) were randomly selected from all live births in WA, matched to cases by sex and date of birth. Total ambient erythemal ultraviolet radiation (UVR) doses for each trimester of pregnancy and first year of life were estimated for each individual, using daily NASA satellite data that were date- and geographically-specific. Conditional logistic regression tested the association between UVR dose and case–control status. Type 1 diabetes risk was 42% lower in boys of mothers with third-trimester UVR dose in the highest (compared to the lowest) quartile (p = 0.04). Higher UVR in the first year of life was associated with lower type 1 diabetes risk among boys (p = 0.01). UVR dose was not associated with type 1 diabetes risk in girls. Higher UVR in late pregnancy and early life appear to interact with sex-specific factors to lower type 1 diabetes risk among boys in Western Australia.

Objective This study aimed to explore current attitudes towards sun protection, and sun-seeking behaviour among young Australian adolescents. It was done as part of a larger project aiming to develop a digital resource to support young people in making informed sun-health decisions. Results Ten (4 male, 6 female) adolescents (12–13 years of age) living in Perth (Western Australia) were recruited through a social media-based strategy. Each participant engaged in a semi-structured telephone interview which explored their sun-health decision-making, with interview transcripts assessed qualitatively using NVivo. Three major themes (and eight sub-themes) were identified: (1) ‘personal sun health considerations’; (2) ‘attitudes towards sun protection’; and (3) ‘recommendations’. The importance of sun protection was appreciated by participants. However, females were more diligent in the use of sun protection while males were indifferent. Behaviours were influenced by parental input, the school environment and engagement in sport. Adolescents had limited knowledge of the UV Index and its implications for sun protection, and the health importance of sun-derived vitamin D. Overall, the importance of sun protection was acknowledged but did not consistently translate into sun protective behaviours.