Miles D. Witham

Effect of vitamin D on blood pressure: a systematic review and meta-analysis.

Objectives Vitamin D insufficiency has been linked to hypertension and cardiovascular events in observational studies. It is unclear whether vitamin D supplementation can reduce blood pressure, and, if so, by how much. Methods We performed a systematic review and meta-analysis to examine whether vitamin D reduces blood pressure. Databases including MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature and the Cochrane library were searched, supplemented by searches of grey literature, unpublished trials and references from included studies. Studies were assessed by two reviewers independently according to a prespecified protocol. Interventions included activated vitamin D, unactivated vitamin D2 and D3 and ultraviolet B radiation. Results Eleven randomized, controlled trials fulfilled the inclusion criteria. Studies were small and of variable methodological quality. Mean baseline blood pressure was more than 140/90 mmHg in eight studies. Meta-analysis of these eight studies showed a nonsignificant reduction in systolic blood pressure in the vitamin D group compared with placebo [−3.6 mmHg, 95% confidence interval (CI) −8.0 to 0.7]. A small, statistically significant reduction was seen in diastolic blood pressure (−3.1 mmHg, 95% CI −5.5 to −0.6). Subgroup analysis suggested that unactivated vitamin D produced a greater fall in systolic blood pressure than activated vitamin D (−6.2 mmHg, 95% CI −12.32 to −0.04, vs. +0.7 mmHg, 95% CI −4.8 to 6.2). No reduction in blood pressure was seen in studies examining patients who were normotensive at baseline. Conclusion We found weak evidence to support a small effect of vitamin D on blood pressure in studies of hypertensive patients.

Family caregiving and congestive heart failure. Review and analysis.

There is increasing evidence that discharge planning and post‐discharge support for CHF patients can contribute greatly to the medical management of heart failure (CHF) in the community and that the quality of the CHF patients close personal relationships can influence outcome in CHF. However, there has been little research on the impact of CHF on the family or the role of the family in the management of the condition. In this paper, we provide a review and analysis of studies that have explicitly investigated these issues in the informal carers of CHF patients.

Effect of perindopril on physical function in elderly people with functional impairment: a randomized controlled trial

Background: Physical function and exercise capacity decline with age and are a major source of disability in older people. Recent evidence suggests a potential role for the renin–angiotensin system in modulating muscle function. We sought to examine the effect of the angiotensin-converting-enzyme (ACE) inhibitor perindopril on physical function in elderly people with functional impairment who had no heart failure or left ventricular systolic dysfunction. Methods: In this double-blind randomized controlled trial, participants aged 65 years and older who had problems with mobility or functional impairment were randomly assigned to receive either perindopril or placebo for 20 weeks. The primary outcome was the change in the 6-minute walking distance over the 20 weeks. Secondary outcomes were changes in muscle function, daily activity levels, self-reported function and health-related quality of life. Results: A total of 130 participants were enrolled in the study (mean age 78.7, standard deviation 7.7 years); 95 completed the trial. At 20 weeks, the mean 6-minute walking distance was significantly improved in the perindopril group relative to the placebo group (mean between-group difference 31.4 m, 95% confidence interval [CI] 10.8 to 51.9 m; p = 0.003). There was a significant impact on health-related quality of life: although the mean score for part 1 of the EQ-5D questionnaire deteriorated over time in the placebo group, quality of life was maintained in the perindopril group, for a between-group difference of 0.09 (p = 0.046). There were no significant differences between the 2 groups in the other outcomes. Interpretation: Use of the ACE inhibitor perindopril improved exercise capacity in functionally impaired elderly people who had no heart failure and maintained health-related quality of life. The degree of improvement was equivalent to that reported after 6 months of exercise training. (International Standard Randomised Controlled Trial Register no. ISRCTN67679521).

Including older people in clinical research.

Benefits shown in trials in younger people may not apply to older people T here are more old people alive today than at any time in history. Older people are, quite rightly, “the core business of the NHS.”1 The need to be able to draw on the results of good quality research to inform best practice in the specific management of older people is compelling. So we might expect that researchers would have eagerly embraced the participation of older people in clinical trials. Yet this is not the case. What do clinicians and researchers have to do to redress the serious bias against older people in clinical research? The evidence that older people are being excluded from clinical research is widespread. Although the world is facing a global increase in the prevalence of diabetes mellitus, and by 2030 it is estimated that over 48 million older people in developed countries will have diabetes, the mean age of participants in the United Kingdom Progression of Diabetes Study was only 53 years. Guidelines on older people with diabetes have acknowledged …

Cardiovascular disease and vitamin D supplementation: trial analysis, systematic review, and meta-analysis

BACKGROUND Low 25-hydroxyvitamin D status has been associated with increased cardiovascular events in epidemiologic studies. OBJECTIVE We assessed whether vitamin D supplementation reduces cardiac failure, myocardial infarction (MI), and stroke through an analysis of the Randomised Evaluation of Calcium Or vitamin D (RECORD) randomized controlled trial (RCT), a systematic review, and a meta-analysis. DESIGN Two analyses were undertaken. The first analysis was a trial analysis. The RECORD was a factorial RCT that compared vitamin D₃ (800 IU/d), calcium (1000 mg/d), vitamin D plus calcium, and a placebo. Cardiovascular events were collected throughout the trial and 3-y posttrial follow-up. Data were analyzed by using Cox regression. The second analysis was a systematic review. MEDLINE, EMBASE, CENTRAL, conference abstracts, and ongoing trials were searched for RCTs that evaluated vitamin D from 1980 to 2013. RCTs with ≥1 y of follow-up and participants mean or median age ≥60 y were included. Meta-analyses were based on a Bayesian fixed-effects model by using a complementary log-log link function to account for varying lengths of follow-up. RESULTS In the trial analysis, we showed that, for the 5292 participants in the RECORD trial, HRs (95% CIs) for vitamin D compared with no vitamin D for cardiac failure, MI, and stroke were 0.75 (0.58, 0.97), 0.97 (0.75,1.26), and 1.06 (0.8, 1.32), respectively. Twenty-one studies met the inclusion criteria for the systematic review (n = 13,033). Estimated HRs (credible intervals) for vitamin D compared with the placebo or control for on-study events for cardiac failure, MI, and stroke were 0.82 (0.58, 1.15), 0.96 ( 0.83, 1.10), and 1.07 (0.91, 1.29), respectively. CONCLUSION Vitamin D supplementation might protect against cardiac failure in older people but does not appear to protect against MI or stroke.

The Effects of Vitamin D Supplementation on Physical Function and Quality of Life in Older Patients With Heart Failure A Randomized Controlled Trial

Background—Low 25-hydroxyvitamin D levels, commonly found in older patients with heart failure, may contribute to the chronic inflammation and skeletal myopathy that lead to poor exercise tolerance. We tested whether vitamin D supplementation of patients with heart failure and vitamin D insufficiency can improve physical function and quality of life. Methods and Results—In a randomized, parallel group, double-blind, placebo-controlled trial, patients with systolic heart failure aged ≥70 years with 25-hydroxyvitamin D levels <50 nmol/L (20 ng/mL) received 100000 U of oral vitamin D2 or placebo at baseline and 10 weeks. Outcomes measured at baseline, 10 weeks, and 20 weeks were 6-minute walk distance, quality of life (Minnesota score), daily activity measured by accelerometry, Functional Limitations Profile, B-type natriuretic peptide, and tumor necrosis factor-&agr;. Participants in the vitamin D group had an increase in their 25-hydroxyvitamin D levels compared with placebo at 10 weeks (22.9 versus 2.3 nmol/L [9.2 versus 0.9 ng/mL]; P<0.001) and maintained this increase at 20 weeks. The 6-minute walk did not improve in the treatment group relative to placebo. No significant benefit was seen on timed up and go testing, subjective measures of function, daily activity, or tumor necrosis factor. Quality of life worsened by a small, but significant amount in the treatment group relative to placebo. B-type natriuretic peptide decreased in the treatment group relative to placebo (−22 versus +78 pg/mL at 10 weeks; P=0.04). Conclusions—Vitamin D supplementation did not improve functional capacity or quality of life in older patients with heart failure with vitamin D insufficiency. Clinical Trial Registration—www.controlled-trials.com. Identifier: ISRCTN51372896.

Effect of Vitamin D Supplementation on Blood Pressure: A Systematic Review and Meta-analysis Incorporating Individual Patient Data

IMPORTANCE Low levels of vitamin D are associated with elevated blood pressure (BP) and future cardiovascular events. Whether vitamin D supplementation reduces BP and which patient characteristics predict a response remain unclear. OBJECTIVE To systematically review whether supplementation with vitamin D or its analogues reduce BP. DATA SOURCES We searched MEDLINE, CINAHL, EMBASE, Cochrane Central Register of Controlled Trials, and http://www.ClinicalTrials.com augmented by a hand search of references from the included articles and previous reviews. Google was searched for gray literature (ie, material not published in recognized scientific journals). No language restrictions were applied. The search period spanned January 1, 1966, through March 31, 2014. STUDY SELECTION We included randomized placebo-controlled clinical trials that used vitamin D supplementation for a minimum of 4 weeks for any indication and reported BP data. Studies were included if they used active or inactive forms of vitamin D or vitamin D analogues. Cointerventions were permitted if identical in all treatment arms. DATA EXTRACTION AND SYNTHESIS We extracted data on baseline demographics, 25-hydroxyvitamin D levels, systolic and diastolic BP (SBP and DBP), and change in BP from baseline to the final follow-up. Individual patient data on age, sex, medication use, diabetes mellitus, baseline and follow-up BP, and 25-hydroxyvitamin D levels were requested from the authors of the included studies. For trial-level data, between-group differences in BP change were combined in a random-effects model. For individual patient data, between-group differences in BP at the final follow up, adjusted for baseline BP, were calculated before combining in a random-effects model. MAIN OUTCOMES AND MEASURES Difference in SBP and DBP measured in an office setting. RESULTS We included 46 trials (4541 participants) in the trial-level meta-analysis. Individual patient data were obtained for 27 trials (3092 participants). At the trial level, no effect of vitamin D supplementation was seen on SBP (effect size, 0.0 [95% CI, -0.8 to 0.8] mm Hg; P=.97; I2=21%) or DBP (effect size, -0.1 [95% CI, -0.6 to 0.5] mm Hg; P=.84; I2=20%). Similar results were found analyzing individual patient data for SBP (effect size, -0.5 [95% CI, -1.3 to 0.4] mm Hg; P=.27; I2=0%) and DBP (effect size, 0.2 [95% CI, -0.3 to 0.7] mm Hg; P=.38; I2=0%). Subgroup analysis did not reveal any baseline factor predictive of a better response to therapy. CONCLUSIONS AND RELEVANCE Vitamin D supplementation is ineffective as an agent for lowering BP and thus should not be used as an antihypertensive agent.

The Effects of Vitamin D Supplementation on Physical Function and Quality of Life in Older Patients With Heart FailureCLINICAL PERSPECTIVE

Background—Low 25-hydroxyvitamin D levels, commonly found in older patients with heart failure, may contribute to the chronic inflammation and skeletal myopathy that lead to poor exercise tolerance. We tested whether vitamin D supplementation of patients with heart failure and vitamin D insufficiency can improve physical function and quality of life. Methods and Results—In a randomized, parallel group, double-blind, placebo-controlled trial, patients with systolic heart failure aged ≥70 years with 25-hydroxyvitamin D levels <50 nmol/L (20 ng/mL) received 100000 U of oral vitamin D2 or placebo at baseline and 10 weeks. Outcomes measured at baseline, 10 weeks, and 20 weeks were 6-minute walk distance, quality of life (Minnesota score), daily activity measured by accelerometry, Functional Limitations Profile, B-type natriuretic peptide, and tumor necrosis factor-&agr;. Participants in the vitamin D group had an increase in their 25-hydroxyvitamin D levels compared with placebo at 10 weeks (22.9 versus 2.3 nmol/L [9.2 versus 0.9 ng/mL]; P<0.001) and maintained this increase at 20 weeks. The 6-minute walk did not improve in the treatment group relative to placebo. No significant benefit was seen on timed up and go testing, subjective measures of function, daily activity, or tumor necrosis factor. Quality of life worsened by a small, but significant amount in the treatment group relative to placebo. B-type natriuretic peptide decreased in the treatment group relative to placebo (−22 versus +78 pg/mL at 10 weeks; P=0.04). Conclusions—Vitamin D supplementation did not improve functional capacity or quality of life in older patients with heart failure with vitamin D insufficiency. Clinical Trial Registration—www.controlled-trials.com. Identifier: ISRCTN51372896.

The effect of vitamin D replacement on markers of vascular health in stroke patients – A randomised controlled trial

BACKGROUND AND AIMS Low vitamin D levels are associated with increased incidence of future cardiovascular events and are common in stroke patients. We tested whether vitamin D supplementation could reduce blood pressure and improve markers of vascular health in patients who had previously suffered a stroke. METHODS AND RESULTS Randomised, placebo-controlled, double-blind trial. Community-dwelling patients with a history of stroke and baseline 25-hydroxyvitamin D levels <75 nmol/L received 100,000 units of oral vitamin D2 or placebo at baseline. Office and 24 h blood pressure, endothelial function measured by flow-mediated dilatation of the brachial artery, cholesterol, oxidised low density lipoprotein, B-type natriuretic peptide and heart rate turbulence were measured at baseline, 8 weeks and 16 weeks. 58 patients were randomised. Mean age was 67 years, mean baseline blood pressure 128/72 mmHg, mean baseline 25-hydroxyvitamin D level was 38 nmol/L. Serum 25-hydroxyvitamin D levels were higher in the intervention group at 8 weeks compared to placebo (54 vs 42 nmol/L, P = 0.002) and remained higher at 16 weeks. Office systolic and diastolic blood pressure showed no significant change between groups at 8 weeks (systolic 126.1 vs 131.3 mmHg; adjusted P = 0.97); (diastolic 73.1 vs 74.9 mmHg, adjusted P = 0.15). Flow mediated dilatation was significantly higher in the intervention group at 8 weeks (6.9% vs 3.7%, adjusted P = 0.007) but was not significantly different at 16 weeks. CONCLUSIONS High dose oral vitamin D supplementation did not improve blood pressure but produced short-term improvement in endothelial function in stroke patients with well-controlled baseline blood pressure. CLINICAL TRIALS REGISTRATION ISRCTN28737567.

Can vitamin D deficiency cause diabetes and cardiovascular diseases? Present evidence and future perspectives.

Several studies have shown that vitamin D may play a role in many biochemical mechanisms in addition to bone and calcium metabolism. Recently, vitamin D has sparked widespread interest because of its involvement in the homeostasis of the cardiovascular system. Hypovitaminosis D has been associated with obesity, related to trapping in adipose tissue due to its lipophilic structure. In addition, vitamin D deficiency is associated with increased risk of cardiovascular disease (CVD) and this may be due to the relationship between low vitamin D levels and obesity, diabetes mellitus, dyslipidaemia, endothelial dysfunction and hypertension. However, although vitamin D has been identified as a potentially important marker of CVD, the mechanisms through which it might modulate cardiovascular risk are not fully understood. Given this background, in this work we summarise clinical retrospective and prospective observational studies linking vitamin D levels with cardio-metabolic risk factors and vascular outcome. Moreover, we review various randomised controlled trials (RCTs) investigating the effects of vitamin D supplementation on surrogate markers of cardiovascular risk. Considering the high prevalence of hypovitaminosis D among patients with high cardiovascular risk, vitamin D replacement therapy in this population may be warranted; however, further RCTs are urgently needed to establish when to begin vitamin D therapy, as well as to determine the dose and route and duration of administration.