Administration of a supplement containing both calcium and vitamin D is more effective than calcium alone to reduce secondary hyperparathyroidism in postmenopausal women with low 25(OH)vitamin D circulating levels

Treatment of Vitamin D Insufficiency in Postmenopausal Women: A Randomized Clinical Trial

IMPORTANCE

Experts debate optimal 25-hydroxyvitamin D (25[OH]D) levels for musculoskeletal health.

OBJECTIVE

To compare the effects of placebo, low-dose cholecalciferol, and high-dose cholecalciferol on 1-year changes in total fractional calcium absorption, bone mineral density, Timed Up and Go and five sit-to-stand tests, and muscle mass in postmenopausal women with vitamin D insufficiency.

DESIGN, SETTING, AND PARTICIPANTS

This randomized, double-blind, placebo-controlled clinical trial was conducted at a single center in Madison, Wisconsin, from May 1, 2010, through July 31, 2013, and the final visit was completed on August 8, 2014. A total of 230 postmenopausal women 75 years or younger with baseline 25(OH)D levels of 14 through 27 ng/mL and no osteoporosis were studied.

INTERVENTIONS

Three arms included daily white and twice monthly yellow placebo (n=76), daily 800 IU vitamin D3 and twice monthly yellow placebo (n=75), and daily white placebo and twice monthly 50,000 IU vitamin D3 (n=79). The high-dose vitamin D regimen achieved and maintained 25(OH)D levels≥30 ng/mL.

MAIN OUTCOMES AND MEASURES

Outcome measures were 1-year change in total fractional calcium absorption using 2 stable isotopes, bone mineral density and muscle mass using dual energy x-ray absorptiometry, Timed Up and Go and five sit-to-stand tests, functional status (Health Assessment Questionnaire), and physical activity (Physical Activity Scale for the Elderly), with Benjamini-Hochberg correction of P values to control for the false discovery rate.

RESULTS

After baseline absorption was controlled for, calcium absorption increased 1% (10 mg/d) in the high-dose arm but decreased 2% in the low-dose arm (P = .005 vs high-dose arm) and 1.3% in the placebo arm (P = .03 vs high-dose arm). We found no between-arm changes in spine, mean total-hip, mean femoral neck, or total-body bone mineral density, trabecular bone score, muscle mass, and Timed Up and Go or five sit-to-stand test scores. Likewise, we found no between-arm differences for numbers of falls, number of fallers, physical activity, or functional status.

CONCLUSIONS AND RELEVANCE

High-dose cholecalciferol therapy increased calcium absorption, but the effect was small and did not translate into beneficial effects on bone mineral density, muscle function, muscle mass, or falls. We found no data to support experts' recommendations to maintain serum 25(OH)D levels of 30 ng/mL or higher in postmenopausal women. Instead, we found that low- and high-dose cholecalciferol were equivalent to placebo in their effects on bone and muscle outcomes in this cohort of postmenopausal women with 25(OH)D levels less than 30 ng/mL.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00933244.

Vitamin D and vitamin D analogues for preventing fractures in post-menopausal women and older men

BACKGROUND

Vitamin D and related compounds have been used to prevent osteoporotic fractures in older people. This is the third update of a Cochrane review first published in 1996.

OBJECTIVES

To determine the effects of vitamin D or related compounds, with or without calcium, for preventing fractures in post-menopausal women and older men.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (to December 2012), the Cochrane Central Register of Controlled Trials (2012, Issue 12), MEDLINE (1966 to November Week 3 2012), EMBASE (1980 to 2012 Week 50), CINAHL (1982 to December 2012), BIOSIS (1985 to 3 January 2013), Current Controlled Trials (December 2012) and reference lists of articles.

SELECTION CRITERIA

Randomised or quasi-randomised trials that compared vitamin D or related compounds, alone or with calcium, against placebo, no intervention or calcium alone, and that reported fracture outcomes in older people. The primary outcome was hip fracture.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial risk of selection bias and aspects of methodological quality, and extracted data. Data were pooled, where possible, using the fixed-effect model, or the random-effects model when heterogeneity between studies appeared substantial.

MAIN RESULTS

We included 53 trials with a total of 91,791 participants. Thirty-one trials, with sample sizes ranging from 70 to 36,282 participants, examined vitamin D (including 25-hydroxy vitamin D) with or without calcium in the prevention of fractures in community, nursing home or hospital inpatient populations. Twelve of these 31 trials had participants with a mean or median age of 80 years or over.Another group of 22 smaller trials examined calcitriol or alfacalcidol (1-alphahydroxyvitamin D3), mostly with participants who had established osteoporosis. These trials were carried out in the setting of institutional referral clinics or hospitals.In the assessment of risk of bias for random sequence generation, 21 trials (40%) were deemed to be at low risk, 28 trials (53%) at unclear risk and four trials at high risk (8%). For allocation concealment, 22 trials were at low risk (42%), 29 trials were at unclear risk (55%) and two trials were at high risk (4%).There is high quality evidence that vitamin D alone, in the formats and doses tested, is unlikely to be effective in preventing hip fracture (11 trials, 27,693 participants; risk ratio (RR) 1.12, 95% confidence intervals (CI) 0.98 to 1.29) or any new fracture (15 trials, 28,271 participants; RR 1.03, 95% CI 0.96 to 1.11).There is high quality evidence that vitamin D plus calcium results in a small reduction in hip fracture risk (nine trials, 49,853 participants; RR 0.84, 95% confidence interval (CI) 0.74 to 0.96; P value 0.01). In low-risk populations (residents in the community: with an estimated eight hip fractures per 1000 per year), this equates to one fewer hip fracture per 1000 older adults per year (95% CI 0 to 2). In high risk populations (residents in institutions: with an estimated 54 hip fractures per 1000 per year), this equates to nine fewer hip fractures per 1000 older adults per year (95% CI 2 to 14). There is high quality evidence that vitamin D plus calcium is associated with a statistically significant reduction in incidence of new non-vertebral fractures. However, there is only moderate quality evidence of an absence of a statistically significant preventive effect on clinical vertebral fractures. There is high quality evidence that vitamin D plus calcium reduces the risk of any type of fracture (10 trials, 49,976 participants; RR 0.95, 95% CI 0.90 to 0.99).In terms of the results for adverse effects: mortality was not adversely affected by either vitamin D or vitamin D plus calcium supplementation (29 trials, 71,032 participants, RR 0.97, 95% CI 0.93 to 1.01). Hypercalcaemia, which was usually mild (2.6 to 2.8 mmol/L), was more common in people receiving vitamin D or an analogue, with or without calcium (21 trials, 17,124 participants, RR 2.28, 95% CI 1.57 to 3.31), especially for calcitriol (four trials, 988 participants, RR 4.41, 95% CI 2.14 to 9.09), than in people receiving placebo or control. There was also a small increased risk of gastrointestinal symptoms (15 trials, 47,761 participants, RR 1.04, 95% CI 1.00 to 1.08), especially for calcium plus vitamin D (four trials, 40,524 participants, RR 1.05, 95% CI 1.01 to 1.09), and a significant increase in renal disease (11 trials, 46,548 participants, RR 1.16, 95% CI 1.02 to 1.33). Other systematic reviews have found an increased association of myocardial infarction with supplemental calcium; and evidence of increased myocardial infarction and stroke, but decreased cancer, with supplemental calcium plus vitamin D, without an overall effect on mortality.

AUTHORS' CONCLUSIONS

Vitamin D alone is unlikely to prevent fractures in the doses and formulations tested so far in older people. Supplements of vitamin D and calcium may prevent hip or any type of fracture. There was a small but significant increase in gastrointestinal symptoms and renal disease associated with vitamin D and calcium. This review found that there was no increased risk of death from taking calcium and vitamin D.

Vitamin D supplementation for prevention of mortality in adults

BACKGROUND

Available evidence on the effects of vitamin D on mortality has been inconclusive. In a recent systematic review, we found evidence that vitamin D3 may decrease mortality in mostly elderly women. The present systematic review updates and reassesses the benefits and harms of vitamin D supplementation used in primary and secondary prophylaxis of mortality.

OBJECTIVES

To assess the beneficial and harmful effects of vitamin D supplementation for prevention of mortality in healthy adults and adults in a stable phase of disease.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, LILACS, the Science Citation Index-Expanded and Conference Proceedings Citation Index-Science (all up to February 2012). We checked references of included trials and pharmaceutical companies for unidentified relevant trials.

SELECTION CRITERIA

Randomised trials that compared any type of vitamin D in any dose with any duration and route of administration versus placebo or no intervention in adult participants. Participants could have been recruited from the general population or from patients diagnosed with a disease in a stable phase. Vitamin D could have been administered as supplemental vitamin D (vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol)) or as an active form of vitamin D (1α-hydroxyvitamin D (alfacalcidol) or 1,25-dihydroxyvitamin D (calcitriol)).

DATA COLLECTION AND ANALYSIS

Six review authors extracted data independently. Random-effects and fixed-effect meta-analyses were conducted. For dichotomous outcomes, we calculated the risk ratios (RRs). To account for trials with zero events, we performed meta-analyses of dichotomous data using risk differences (RDs) and empirical continuity corrections. We used published data and data obtained by contacting trial authors.To minimise the risk of systematic error, we assessed the risk of bias of the included trials. Trial sequential analyses controlled the risk of random errors possibly caused by cumulative meta-analyses.

MAIN RESULTS

We identified 159 randomised clinical trials. Ninety-four trials reported no mortality, and nine trials reported mortality but did not report in which intervention group the mortality occurred. Accordingly, 56 randomised trials with 95,286 participants provided usable data on mortality. The age of participants ranged from 18 to 107 years. Most trials included women older than 70 years. The mean proportion of women was 77%. Forty-eight of the trials randomly assigned 94,491 healthy participants. Of these, four trials included healthy volunteers, nine trials included postmenopausal women and 35 trials included older people living on their own or in institutional care. The remaining eight trials randomly assigned 795 participants with neurological, cardiovascular, respiratory or rheumatoid diseases. Vitamin D was administered for a weighted mean of 4.4 years. More than half of the trials had a low risk of bias. All trials were conducted in high-income countries. Forty-five trials (80%) reported the baseline vitamin D status of participants based on serum 25-hydroxyvitamin D levels. Participants in 19 trials had vitamin D adequacy (at or above 20 ng/mL). Participants in the remaining 26 trials had vitamin D insufficiency (less than 20 ng/mL).Vitamin D decreased mortality in all 56 trials analysed together (5,920/47,472 (12.5%) vs 6,077/47,814 (12.7%); RR 0.97 (95% confidence interval (CI) 0.94 to 0.99); P = 0.02; I(2) = 0%). More than 8% of participants dropped out. 'Worst-best case' and 'best-worst case' scenario analyses demonstrated that vitamin D could be associated with a dramatic increase or decrease in mortality. When different forms of vitamin D were assessed in separate analyses, only vitamin D3 decreased mortality (4,153/37,817 (11.0%) vs 4,340/38,110 (11.4%); RR 0.94 (95% CI 0.91 to 0.98); P = 0.002; I(2) = 0%; 75,927 participants; 38 trials). Vitamin D2, alfacalcidol and calcitriol did not significantly affect mortality. A subgroup analysis of trials at high risk of bias suggested that vitamin D2 may even increase mortality, but this finding could be due to random errors. Trial sequential analysis supported our finding regarding vitamin D3, with the cumulative Z-score breaking the trial sequential monitoring boundary for benefit, corresponding to 150 people treated over five years to prevent one additional death. We did not observe any statistically significant differences in the effect of vitamin D on mortality in subgroup analyses of trials at low risk of bias compared with trials at high risk of bias; of trials using placebo compared with trials using no intervention in the control group; of trials with no risk of industry bias compared with trials with risk of industry bias; of trials assessing primary prevention compared with trials assessing secondary prevention; of trials including participants with vitamin D level below 20 ng/mL at entry compared with trials including participants with vitamin D levels equal to or greater than 20 ng/mL at entry; of trials including ambulatory participants compared with trials including institutionalised participants; of trials using concomitant calcium supplementation compared with trials without calcium; of trials using a dose below 800 IU per day compared with trials using doses above 800 IU per day; and of trials including only women compared with trials including both sexes or only men. Vitamin D3 statistically significantly decreased cancer mortality (RR 0.88 (95% CI 0.78 to 0.98); P = 0.02; I(2) = 0%; 44,492 participants; 4 trials). Vitamin D3 combined with calcium increased the risk of nephrolithiasis (RR 1.17 (95% CI 1.02 to 1.34); P = 0.02; I(2) = 0%; 42,876 participants; 4 trials). Alfacalcidol and calcitriol increased the risk of hypercalcaemia (RR 3.18 (95% CI 1.17 to 8.68); P = 0.02; I(2) = 17%; 710 participants; 3 trials).

AUTHORS' CONCLUSIONS

Vitamin D3 seemed to decrease mortality in elderly people living independently or in institutional care. Vitamin D2, alfacalcidol and calcitriol had no statistically significant beneficial effects on mortality. Vitamin D3 combined with calcium increased nephrolithiasis. Both alfacalcidol and calcitriol increased hypercalcaemia. Because of risks of attrition bias originating from substantial dropout of participants and of outcome reporting bias due to a number of trials not reporting on mortality, as well as a number of other weaknesses in our evidence, further placebo-controlled randomised trials seem warranted.

Vitamin D dose response is underestimated by Endocrine Society's Clinical Practice Guideline

OBJECTIVE

The recommended daily intakes of vitamin D according to the recent Clinical Practice Guideline (CPG) of the Endocrine Society are three- to fivefold higher than the Institute of Medicine (IOM) report. We speculated that these differences could be explained by different mathematical approaches to the vitamin D dose response.

METHODS

Studies were selected if the daily dose was ≤2000 IU/day, the duration exceeded 3 months, and 25-hydroxyvitamin D (25OHD) concentrations were measured at baseline and post-therapy. The rate constant was estimated according to the CPG approach. The achieved 25OHD result was estimated according to the following: i) the regression equation approach of the IOM; ii) the regression approach of the Vitamin D Supplementation in Older Subjects (ViDOS) study; and iii) the CPG approach using a rate constant of 2.5 (CPG2.5) and a rate constant of 5.0 (CPG5.0). The difference between the expected and the observed 25OHD result was expressed as a percentage of observed and analyzed for significance against a value of 0% for the four groups.

RESULTS

Forty-one studies were analyzed. The mean (95% CI) rate constant was 5.3 (4.4-6.2) nmol/l per 100 IU per day, on average twofold higher than the CPG rate constant. The mean (95% CI) for the difference between the expected and observed expressed as a percentage of observed was as follows: i) IOM, -7 (-16,+2)% (t=1.64, P=0.110); ii) ViDOS, +2 (-8,+12)% (t=0.40, P=0.69); iii) CPG2.5, -21 (-27,-15)% (t=7.2, P<0.0001); and iv) CPG5.0+3 (-4,+10)% (t=0.91, P=0.366).

CONCLUSION

The CPG 'rule of thumb' should be doubled to 5.0 nmol/l (2.0 ng/ml) per 100 IU per day, adopting a more risk-averse position.

Vitamin D and vitamin D analogues for preventing fractures associated with involutional and post-menopausal osteoporosis

BACKGROUND

Vitamin D and related compounds have been used to prevent osteoporotic fractures in older people.

OBJECTIVES

To determine the effects of vitamin D or related compounds, with or without calcium, for preventing fractures in older people.

SEARCH STRATEGY

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 3), MEDLINE, EMBASE, CINAHL, and reference lists of articles. Most recent search: October 2007.

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing vitamin D or related compounds, alone or with calcium, against placebo, no intervention, or calcium alone, reporting fracture outcomes in older people.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality, and extracted data. Data were pooled, where admissible, using the fixed-effect model, or random-effects model if heterogeneity between studies appeared high.

MAIN RESULTS

Forty-five trials were included. Vitamin D alone appears unlikely to be effective in preventing hip fracture (nine trials, 24,749 participants, RR 1.15, 95% CI 0.99 to 1.33), vertebral fracture (five trials, 9138 participants, RR 0.90, 95% CI 0.42 to 1.92) or any new fracture (10 trials, 25,016 participants, RR 1.01, 95% CI 0.93 to 1.09).Vitamin D with calcium reduces hip fractures (eight trials, 46,658 participants, RR 0.84, 95% CI 0.73 to 0.96). Although subgroup analysis by residential status showed a significant reduction in hip fractures in people in institutional care, the difference between this and the community-dwelling subgroup was not significant (P = 0.15).Overall hypercalcaemia is significantly more common in people receiving vitamin D or an analogue, with or without calcium (18 trials, 11,346 participants, RR 2.35, 95% CI 1.59 to 3.47); this is especially true of calcitriol (four trials, 988 participants, RR 4.41, 95% CI 2.14 to 9.09). There is a modest increase in gastrointestinal symptoms (11 trials, 47,042 participants, RR 1.04, 95% CI 1.00 to 1.08, P = 0.04) and a small but significant increase in renal disease (11 trials, 46,537 participants, RR 1.16, 95% CI 1.02 to 1.33).

AUTHORS' CONCLUSIONS

Frail older people confined to institutions may sustain fewer hip fractures if given vitamin D with calcium. Vitamin D alone is unlikely to prevent fracture. Overall there is a small but significant increase in gastrointestinal symptoms and renal disease associated with vitamin D or its analogues. Calcitriol is associated with an increased incidence of hypercalcaemia.

Vitamin D insufficiency: disease or no disease?

Vitamin D insufficiency (VDI) is widely reported. In patients with normal PTH, the diagnosis rests on increases in fractional calcium absorption (FCA) when 25(OH)D increases above 30 ng/ml. However, estimates of increased FCA after correction of VDI vary dramatically, depending on study methods. We used a dual stable calcium isotope to clarify the impact of vitamin D repletion on FCA in postmenopausal women with VDI. We hypothesized that FCA would increase with vitamin D repletion. We studied postmenopausal women with VDI [25(OH)D = 16-24 ng/ml] and an estimated calcium intake <or=1100 mg daily. Exclusion criteria included hypercalcemia, hypercalciuria, renal insufficiency, nephrolithiasis, gastrointestinal disorders, osteomalacia, prior adult fragility fracture, baseline T-score < -3.0, and use of medications known to interfere with vitamin D or calcium metabolism. Each woman underwent inpatient FCA studies before and after correction of VDI. We used ergocalciferol 50,000 IU/d for 15 days to achieve vitamin D repletion. During each study, women consumed their typical diet. They ingested (44)Ca orally with breakfast and received (42)Ca intravenously. We collected urine for 24 h and measured its calcium isotope content by mass spectrometry. Eighteen women completed the study; all but two had normal PTH. During the first and second FCA studies, their mean 25(OH)D level was 22 +/- 4 and 64 +/- 21 ng/ml, respectively (p < 0.001). Subjects' average FCA was 24 +/- 7% initially and 27 +/- 6% after vitamin D repletion (p = 0.04). Thus, FCA increased by 3 +/- 1% with correction of VDI. Postmenopausal women with VDI experience small FCA increments with vitamin D therapy. In existing literature, this small change in FCA does not associate with lower fracture rates or consistently higher bone mass. Future studies should ascertain whether small FCA increments favorably affect the skeleton.

Responses of parathyroid hormone to vitamin D supplementation: a systematic review of clinical trials

The beneficial bone effects of vitamin D supplementation have been attributed to suppression of secondary hyperparathyroidism by 25-hydroxyvitamin D (25-OHD) levels at least 50nmol/l. In this systematic review, we have analyzed the results of 52 clinical trials, including 72 intervention groups and 6290 patients, on vitamin D supplementation in order to evaluate the experimental evidence and the effects of age and chronic immobility on responses of parathyroid hormone (PTH). The papers for this systematic review were selected through a search in PubMed and through a review of the reference lists of articles. Negative logarithmic (R(2)=0.318, p<0.001) and linear (R(2)=0.294, p<0.001) correlations were found between 25-OHD and PTH levels, when all pre- and post-trial values were scattered. Negative linear (R(2)=0.385, p<0.001) and logarithmic (R(2)=0.406, p<0.001) correlations were also found between the changes in 25-OHD and PTH levels. Age correlated negatively with changes in PTH (r=-0.476, p<0.001). The vitamin D supplementation of the chronically immobile patients resulted in a smaller decrease in PTH levels (-8.4 vs. -17.4%, p<0.001) despite a larger increase in 25-OHD levels (187.2% vs. 109.8%, p<0.001). According to the multiple regression analysis the changes in PTH were independently predicted by pre-trial PTH, changes in 25-OHD, age and chronic immobility, explaining 53.2% (R(2)=0.532) of the variation. This meta-analysis shows that responses of PTH to vitamin D supplementation are not only determined by the baseline PTH levels and changes in vitamin D status, but also by age and mobility of the patients. Our results also suggest that PTH decreases quite linearly during vitamin D supplementation at any given 25-OHD level. Longitudinal vitamin D supplementation studies on populations with wide range of mobility and age are needed to further elucidate their confounding effects. In determining the sufficient doses of vitamin D supplementation and adequate 25-OHD levels, these confounding effects and the inter-individual variation in responses of PTH to vitamin D supplementation should be taken into account.

Vitamin D and vitamin D analogues for preventing fractures associated with involutional and post-menopausal osteoporosis

BACKGROUND

Vitamin D and related compounds have been used to prevent fractures.

OBJECTIVES

To determine the effects of vitamin D or analogues, with or without calcium, in the prevention of fractures in older people.

SEARCH STRATEGY

We searched the Cochrane Bone, Joint and Muscle Trauma Group trials register, the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 1, 2005), MEDLINE, EMBASE, CINAHL, and reference lists of articles. Most recent search: March 2005.

SELECTION CRITERIA

Randomised or quasi-randomised trials comparing vitamin D or an analogue, alone or with calcium, against placebo, no intervention, or calcium, reporting fracture outcomes, in older people.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trial quality, and extracted data. Data were pooled, where admissible, using the fixed-effect model, or random-effects model if the relative risks were heterogeneous.

MAIN RESULTS

Vitamin D alone showed no statistically significant effect on hip fracture (seven trials, 18,668 participants, RR 1.17, 95% CI 0.98 to 1.41), vertebral fracture (four trials, 5698 participants, RR (random effects) 1.13, 95% CI 0.50 to 2.55) or any new fracture (eight trials, 18,903 participants, RR 0.99, 95% CI 0.91 to 1.09). Vitamin D with calcium marginally reduced hip fractures (seven trials, 10,376 participants, RR 0.81, 95% CI 0.68 to 0.96), non-vertebral fractures (seven trials, 10,376 participants, RR 0.87, 95% CI 0.78 to 0.97), but there was no evidence of effect of vitamin D with calcium on vertebral fractures. The effect appeared to be restricted to those living in institutional care. Hypercalcaemia was more common when vitamin D or its analogues was given compared with placebo or calcium (14 trials, 8035 participants, RR 2.38, 95% CI 1.52 to 3.71). The risk was particularly high with calcitriol (three trials, 742 participants, RR 14.94, 95% CI 2.95 to 75.61). There was no evidence that vitamin D increased gastro-intestinal symptoms (seven trials, 10,188 participants, RR (random effects) 1.03, 95% CI 0.79 to 1.36) or renal disease (nine trials, 10,107 participants, RR 0.80, 95% CI 0.34 to 1.87).

AUTHORS' CONCLUSIONS

Frail older people confined to institutions may sustain fewer hip and other non-vertebral fractures if given vitamin D with calcium supplements. Effectiveness of vitamin D alone in fracture prevention is unclear. There is no evidence of advantage of analogues of vitamin D compared with vitamin D. Calcitriol may be associated with an increased incidence of adverse effects. Dose, frequency, and route of administration of vitamin D in older people require further investigation.