The effect of three years of vitamin D supplementation on erectile dysfunction: Results from the randomized placebo-controlled D-Health Trial.

BACKGROUND & AIMS: Erectile dysfunction is common among older men and has been associated with low serum 25-hydroxy vitamin D concentration. However, this association may be due to uncontrolled confounding, and there is a paucity of evidence from interventional studies. We aimed to examine the effect of vitamin D supplementation on the prevalence of erectile dysfunction, in an exploratory analysis using data from a large randomized controlled trial. METHODS: The D-Health Trial recruited Australians aged 60-84 years between January 2014 and May 2015 and randomly assigned them to supplementation with 60,000 IU of vitamin D or placebo per month for up to 5 years. Blood samples were collected annually from randomly selected participants (total N = 3943). We assessed erectile dysfunction at the end of the third year of follow-up. We used log-binomial regression to examine the effect of vitamin D on the prevalence of erectile dysfunction overall, and within sub-groups. RESULTS: Of the 11,530 men enrolled, 8920 (77.4 %) completed the erectile dysfunction question and were included in the analysis. After three years of supplementation, the mean serum 25-hydroxy vitamin D concentration was 76 nmol/L (standard deviation (SD) 24.94) in the placebo group and 106 nmol/L (SD 26.76) in the vitamin D group (p < 0.0001). The prevalence of erectile dysfunction was 58.8 % and 59.0 % in the vitamin D and placebo groups, respectively (prevalence ratio 1.00, 95 % CI 0.97, 1.03); there was no evidence of an effect of vitamin D in any subgroup analyses. CONCLUSION: Supplementing older men with vitamin D is unlikely to prevent or improve erectile dysfunction. CLINICAL TRIALS REGISTRY: (ACTRN12613000743763).

The Effect of Vitamin D Supplementation on Hypothyroidism in the Randomized Controlled D-Health Trial.

Background: Hypothyroidism is common, and in iodine-sufficient areas, it is primarily caused by autoimmune destruction of the thyroid gland. Observational studies have consistently shown an inverse association between serum 25-hydroxyvitamin D concentration and autoimmune diseases; however, there is a lack of evidence from randomized controlled trials to support a benefit of vitamin D supplementation, particularly for autoimmune thyroid diseases. We, therefore, aimed to assess the effect of vitamin D supplementation on the incidence of hypothyroidism. Methods: We analyzed data from the D-Health Trial (n = 21,315), a randomized double-blind placebo-controlled trial of 60,000 international units per month of supplemental vitamin D3 among Australians aged 60 years and over. Hypothyroidism, a tertiary outcome of the D-Health Trial, was defined by treatment with levothyroxine, ascertained through linkage with the Australian Pharmaceutical Benefits Scheme. The outcome was time to first prescription of levothyroxine. We began follow-up at 12 months after randomization; people who had died or who had been dispensed levothyroxine during the first year were excluded. Flexible parametric survival models were used to assess the effect of vitamin D supplementation on hypothyroidism, overall and within strata defined by age, sex, body mass index, and predicted baseline vitamin D status. Results: We included 17,851 participants in the main analysis (vitamin D = 8939; placebo = 8912). During a median follow-up of 4.1 years (interquartile range 4.1-4.1), 293 participants developed hypothyroidism (vitamin D = 138 [1.5%]; placebo = 155 [1.7%]). Vitamin D supplementation did not significantly reduce the incidence of hypothyroidism (overall hazard ratio [HR] 0.89; 95% confidence interval [CI] 0.71-1.12). There was some suggestion of an effect in females (overall HR 0.78; CI 0.58-1.06) but not in males (overall HR 1.06; CI 0.74-1.50; p interaction 0.20). Conclusions: Vitamin D supplementation did not reduce the incidence of hypothyroidism overall; however, the possible beneficial effect observed in females warrants further investigation. Clinical Trial Registration: Australian New Zealand Clinical Trials Registry: ACTRN12613000743763.

Vitamin D supplementation and major cardiovascular events: D-Health randomised controlled trial.

OBJECTIVE: To investigate whether supplementing older adults with monthly doses of vitamin D alters the incidence of major cardiovascular events. DESIGN: Randomised, double blind, placebo controlled trial of monthly vitamin D (the D-Health Trial). Computer generated permuted block randomisation was used to allocate treatments. SETTING: Australia from 2014 to 2020. PARTICIPANTS: 21 315 participants aged 60-84 years at enrolment. Exclusion criteria were self-reported hypercalcaemia, hyperparathyroidism, kidney stones, osteomalacia, sarcoidosis, taking >500 IU/day supplemental vitamin D, or unable to give consent because of language or cognitive impairment. INTERVENTION: 60 000 IU/month vitamin D3 (n=10 662) or placebo (n=10 653) taken orally for up to five years. 16 882 participants completed the intervention period: placebo 8270 (77.6%); vitamin D 8552 (80.2%). MAIN OUTCOME MEASURES: The main outcome for this analysis was the occurrence of a major cardiovascular event, including myocardial infarction, stroke, and coronary revascularisation, determined through linkage with administrative datasets. Each event was analysed separately as secondary outcomes. Flexible parametric survival models were used to estimate hazard ratios and 95% confidence intervals. RESULTS: 21 302 people were included in the analysis. The median intervention period was five years. 1336 participants experienced a major cardiovascular event (placebo 699 (6.6%); vitamin D 637 (6.0%)). The rate of major cardiovascular events was lower in the vitamin D group than in the placebo group (hazard ratio 0.91, 95% confidence interval 0.81 to 1.01), especially among those who were taking cardiovascular drugs at baseline (0.84, 0.74 to 0.97; P for interaction=0.12), although the P value for interaction was not significant (<0.05). Overall, the difference in standardised cause specific cumulative incidence at five years was -5.8 events per 1000 participants (95% confidence interval -12.2 to 0.5 per 1000 participants), resulting in a number needed to treat to avoid one major cardiovascular event of 172. The rate of myocardial infarction (hazard ratio 0.81, 95% confidence interval 0.67 to 0.98) and coronary revascularisation (0.89, 0.78 to 1.01) was lower in the vitamin D group, but there was no difference in the rate of stroke (0.99, 0.80 to 1.23). CONCLUSIONS: Vitamin D supplementation might reduce the incidence of major cardiovascular events, although the absolute risk difference was small and the confidence interval was consistent with a null finding. These findings could prompt further evaluation of the role of vitamin D supplementation, particularly in people taking drugs for prevention or treatment of cardiovascular disease. TRIAL REGISTRATION: ACTRN12613000743763.

The effect of vitamin D supplementation on the gut microbiome in older Australians - Results from analyses of the D-Health Trial.

Observational studies suggest a link between vitamin D and the composition of the gut microbiome, but there is little evidence from randomized controlled trials of vitamin D supplementation. We analyzed data from the D-Health Trial, a randomized, double-blind, placebo-controlled trial. We recruited 21,315 Australians aged 60-84 y and randomized them to 60,000 IU of vitamin D3 or placebo monthly for 5 y. Stool samples were collected from a sample of 835 participants (417 in the placebo and 418 in the vitamin D group) approximately 5 y after randomization. We characterized the gut microbiome using 16S rRNA gene sequencing. We used linear regression to compare alpha diversity indices (i.e. Shannon index (primary outcome), richness, inverse Simpson index), and the ratio of Firmicutes to Bacteroidetes between the two groups. We analyzed between-sample (beta) diversity (i.e. Bray Curtis distance and UniFrac index) using principal coordinate analysis and used PERMANOVA to test for significant clustering according to randomization group. We also assessed the difference in the abundance of the 20 most abundant genera between the two groups using negative binomial regression model with adjustment for multiple testing. Approximately half the participants included in this analysis were women (mean age 69.4 y). Vitamin D supplementation did not alter the Shannon diversity index (mean 3.51 versus 3.52 in the placebo and vitamin D groups, respectively, p = 0.50). Similarly, there was little difference between the groups for other alpha diversity indices, the abundance of different genera, and the Firmicutes-to-Bacteroidetes ratio. We did not observe clustering of bacterial communities according to randomization group. In conlusion, monthly doses of 60,000 IU of vitamin D supplementation for 5 y did not alter the composition of the gut microbiome in older Australians.

Vitamin D Supplementation and Antibiotic Use in Older Australian Adults: An Analysis of Data From the D-Health Trial.

BACKGROUND: Vitamin D supplementation may reduce the risk or severity of infection, but this has been investigated in few large population-based trials. We analyzed data from the D-Health Trial, using prescription of antibiotics as a surrogate for infection. METHODS: The D-Health Trial is a randomized, double-blind, placebo-controlled trial in which 21 315 Australians aged 60-84 years were randomized to 60 000 IU of supplementary vitamin D3 or placebo monthly for 5 years. For this analysis, the primary outcome was the number of antibiotic prescription episodes; secondary outcomes were total number of prescriptions, repeat prescription episodes, and antibiotics for urinary tract infection. We estimated incidence rate ratios (IRRs) using negative binomial regression, and odds ratios using logistic regression. RESULTS: Vitamin D supplementation slightly reduced the number of prescription episodes (IRR, 0.98; 95% confidence interval [CI], .95-1.01), total prescriptions (IRR, 0.97; 95% CI, .93-1.00), and repeat prescription episodes (IRR, 0.96; 95% CI, .93-1.00). There was stronger evidence of benefit in people predicted to have insufficient vitamin D at baseline (prescription episodes IRR, 0.93; 95% CI, .87-.99). CONCLUSIONS: Vitamin D may reduce the number of antibiotic prescriptions, particularly in people with low vitamin D status. This supports the hypothesis that vitamin D has a clinically relevant effect on the immune system. CLINICAL TRIALS REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12613000743763. https://www.anzctr.org.au/.

Vitamin D supplementation and risk of falling: outcomes from the randomized, placebo-controlled D-Health Trial.

BACKGROUND: Falls cause considerable morbidity and mortality in older people. It is unclear how vitamin D supplementation affects falls risk, particularly when taken at high doses. We sought to determine whether monthly high-dose vitamin D supplementation reduces risk and incidence of falls. METHODS: We used data from the randomized, double-blind, placebo-controlled D-Health Trial conducted in Australia. Between February 2014 and May 2015, 21 315 participants aged 60-84 years were randomized (1:1) to monthly doses of either 60 000 IU of colecalciferol or placebo for a maximum of 5 years. People who reported a history of osteomalacia, sarcoidosis, hyperparathyroidism, hypercalcaemia or kidney stones or who were taking >500 IU/day supplementary vitamin D were ineligible. Each year, we collected blood samples from ~450 randomly sampled participants from each trial arm and measured 25-hydroxyvitamin D [25(OH)D]. Falls, a prespecified tertiary outcome, were ascertained using annual surveys and, for a subset of participants, 3-month falls diaries. The primary outcome for this analysis was any fall in the month before completing an annual survey. As part of our process to maintain blinding, we used random samples of participants (surveys, n = 16 000; diaries, n = 2400), with equal numbers per group. Participants with no outcome data were excluded. Following an intention-to-treat approach, we analysed outcomes using logistic, ordinal and negative binomial regression. Registration: Australian New Zealand Clinical Trials Registry (ACTRN12613000743763); registered 4 July 2013. RESULTS: Mean treatment duration was 4.3 years (standard deviation [SD] = 1.4 years). Mean serum 25(OH)D concentrations during the trial were 114.8 (SD 30.3) nmol/L and 77.5 (SD 25.2) nmol/L in the vitamin D and placebo groups, respectively. Survey and diary analytic sets included 15 416 and 2200 participants, respectively; approximately half were randomized to vitamin D (surveys: 50.1%; diaries: 50.4%). Vitamin D had no effect on falling in the past month (odds ratio [OR] 1.02, 95% confidence interval [CI] 0.95-1.10). There was an interaction with body mass index (BMI) (P-interaction = 0.001); vitamin D increased risk in participants with BMI < 25 kg/m2 (OR 1.25, 95% CI 1.09-1.43), but there was no effect in those with BMI ≥ 25 kg/m2 (OR 0.95, 95% CI 0.87-1.04). Analyses of diary data were consistent with these findings. The incidence of hypercalcaemia and kidney stones did not differ between groups. CONCLUSIONS: Monthly high-dose vitamin D supplementation did not reduce risk of falling. A possible increased risk of falling with vitamin D supplementation in people with normal BMI warrants further investigation.

Predicting deseasonalised serum 25 hydroxy vitamin D concentrations in the D-Health Trial: An analysis using boosted regression trees.

BACKGROUND: The D-Health Trial aims to determine whether monthly high-dose vitamin D supplementation can reduce the mortality rate and prevent cancer. We did not have adequate statistical power for subgroup analyses, so could not justify the high cost of collecting blood samples at baseline. To enable future exploratory analyses stratified by baseline vitamin D status, we developed models to predict baseline serum 25 hydroxy vitamin D [25(OH)D] concentration. METHODS: We used data and serum 25(OH)D concentrations from participants who gave a blood sample during the trial for compliance monitoring and were randomised to placebo. Data were partitioned into training (80%) and validation (20%) datasets. Deseasonalised serum 25(OH)D concentrations were dichotomised using cut-points of 50, 60 and 75 nmol/L. We fitted boosted regression tree models, based on 13 predictors, and evaluated model performance using the validation data. RESULTS: The training and validation datasets had 1788 (10.5% <50 nmol/L, 23.1% <60 nmol, 48.8 <75 nmol/L) and 447 (11.9% <50 nmol/L, 25.7% <60 nmol/L, and 49.2% <75 nmol/L) samples, respectively. Ambient UV radiation and total intake of vitamin D were the strongest predictors of 'low' serum 25(OH)D concentration. The area under the receiver operating characteristic curves were 0.71, 0.70, and 0.66 for cut-points of <50, <60 and <75 nmol/L respectively. CONCLUSIONS: We exploited compliance monitoring data to develop models to predict serum 25(OH)D concentration for D-Health participants at baseline. This approach may prove useful in other trial settings where there is an obstacle to exhaustive data collection.

The effect of vitamin D supplementation on acute respiratory tract infection in older Australian adults: an analysis of data from the D-Health Trial.

BACKGROUND: Observational studies have linked vitamin D deficiency with acute respiratory tract infection, but results from randomised controlled trials are heterogeneous. We analysed data from the D-Health Trial to determine whether supplementing older Australian adults, recruited from the general population, with monthly doses of vitamin D reduced the risk, duration, and severity of acute respiratory tract infections. METHODS: We used data from the D-Health Trial, a randomised, double-blind, placebo-controlled trial of monthly vitamin D supplementation, for which acute respiratory infection was a pre-specified trial outcome. Participants were supplemented and followed for up to 5 years. The trial was set within the Australian general population, using the Commonwealth Electoral Roll as the sampling frame, but also allowing some volunteers to participate. Participants were men and women aged 60 to 79 years (with volunteers up to age 84 years). Participants were randomly assigned to receive either vitamin D or placebo (1:1) using computer-generated permuted block randomisation, which was stratified by age, sex, and state. This was an automated process and the assignment list was not visible to study staff or investigators. Active and placebo gel capsules, identical in appearance to ensure masking, were labelled A and B and the code was not available to study staff or investigators. Participants were asked to report occurrence of acute respiratory symptoms over the previous month via annual surveys, and a subset of participants completed 8-week respiratory symptom diaries in winter. As part of our process to maintain blinding, a random sample of participants was selected for analysis of survey data and a separate sample selected for analysis of diary data. Blood samples were obtained from a random sample of participants (about 450 per group per year) and serum 25-hydroxy vitamin D (25[OH]D) concentrations were measured to monitor adherence. We used regression models to estimate odds ratios (OR), rate ratios, and rate differences. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12613000743763. FINDINGS: Between Jan 13, 2014, and May 26, 2015, 421 207 invitations were sent, 40 824 people were interested in participating, and 21 315 participants were recruited and randomised. Of the 16 000 participants selected for potential analysis of survey data, 15 373 were included in the analysis; 295 in the vitamin D group and 332 in the placebo group who were missing data for all five annual surveys were excluded from the analysis. Of the 3800 selected for potential analysis of diary data, 3070 were invited to complete the diaries because 730 had already withdrawn. 2598 people were included in the analysis; 218 people in the vitamin D group and 254 in the placebo group were missing data and were therefore excluded from the analysis. In blood samples collected from randomly sampled participants throughout the trial, the mean serum 25(OH)D concentration was 114·8 (SD 30·3) nmol/L in the vitamin D group and 77·5 (25·2) nmol/L in the placebo group. Vitamin D supplementation did not reduce the risk of acute respiratory tract infection (survey OR 0·98, 95% CI 0·93 to 1·02; diary OR 0·98, 0·83 to 1·15). Analyses of diary data showed reductions in the overall duration of symptoms and of severe symptoms, but these were small and unlikely to be clinically significant. INTERPRETATION: Monthly bolus doses of 60 000 IU of vitamin D did not reduce the overall risk of acute respiratory tract infection, but could slightly reduce the duration of symptoms in the general population. These findings suggest that routine vitamin D supplementation of a population that is largely vitamin D replete is unlikely to have a clinically relevant effect on acute respiratory tract infection. FUNDING: National Health and Medical Research Council.

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.

Association of Sun Exposure, Skin Colour and Body Mass Index with Vitamin D Status in Individuals Who Are Morbidly Obese.

Vitamin D deficiency is a common issue, particularly in obese populations, and is tested by assessing serum 25(OH)D concentrations. This study aimed to identify factors that contribute to the vitamin D status in fifty morbidly obese individuals recruited prior to bariatric surgery. Data collected included serum 25(OH)D concentrations, dietary and supplement intake of vitamin D, sun exposure measures, skin colour via spectrophotometry, and genotype analysis of several single nucleotide polymorphisms in the vitamin D metabolism pathway. Results showed a significant correlation between serum 25(OH)D concentrations and age, and serum 25(OH)D and ITAC score (natural skin colour). Natural skin colour accounted for 13.5% of variation in serum 25(OH)D, with every 10° increase in ITAC score (i.e., lighter skin) leading to a 9 nmol/L decrease in serum 25(OH)D. Multiple linear regression using age, ITAC score, and average UV index in the three months prior to testing, significantly predicted serum 25(OH)D concentrations (R² = 29.7%). Single nucleotide polymorphisms for all vitamin D genes tested, showed lower serum 25(OH)D for those with the rare genotype compared to the common genotype; this was most pronounced for fok1 and rs4588, where those with the rare genotype were insufficient (<50 nmol/L), and those with the common genotype were sufficient (≥50 nmol/L). Assessing vitamin D status in individuals with morbid obesity requires testing of 25(OH)D, but potential risk factors for this population include natural skin colour and age.