Design Features of Randomized Clinical Trials of Vitamin D and Falls: A Systematic Review

Effect of vitamin D, calcium, or combined supplementation on fall prevention: a systematic review and updated network meta-analysis

BACKGROUND

The association between vitamin D supplementation and the risk of falls in older adults has been controversial. This systematic review and network meta-analysis aims to assess the efficacy of vitamin D, calcium, and combined supplementation in the prevention of falls.

METHODS

Randomized controlled trials (RCTs) on the efficacy of vitamin D in fall prevention were systematically searched in PubMed, Embase, Cochrane Library, and Web of Science from inception to May 9, 2023. The network meta-analysis was performed using a random effects model in R4.1.3 and Stata15.0. Heterogeneity was evaluated by the I2 statistic, and publication bias was assessed using funnel plots, Begg's test, and Egger's tests. Data were pooled and expressed as relative risk (RR) and 95% confidence interval (CI).

RESULTS

A total of 35 RCTs involving 58,937 participants were included in this study, among which 11 RCTs (31.4%) applied calcium combined with vitamin D. There was low heterogeneity (I2 = 11%) among the included studies. Vitamin D supplementation at 800-1000 International Unit (IU)/d resulted in a lower risk of falls than placebo or no treatment (RR = 0.85, 95%CI: 0.74-0.95). In addition, 800-1000 IU/d of vitamin D with or without calcium were more effective in preventing falls than calcium alone. High-dose vitamin D (> 1000 IU/day) increased the risk of falls compared with 800-1000 IU/d of vitamin D. According to the subgroup analysis, daily administration of 800-1000 IU/d vitamin D was associated with a 22% reduction in the risk of falls (RR = 0.78, 95%CI:0.64-0.92), whereas intermittent vitamin D administration had no preventive effect. Furthermore, 800-1000 IU/d of vitamin D also significantly decreased the risk of falls in old adults with ≤ 50 nmol/L 25-hydroxyvitamin D [25(OH)D] (RR = 0.69, 95%CI:0.52-0.86) but not in individuals with > 50 nmol/L 25(OH)D.

CONCLUSION

Vitamin D supplementation at 800-1000 IU/d is associated with a lower risk of falls among older adults. 800-1000IU/d of vitamin D has a benefit on prevention of falls in population received daily dose regimens and in population with vitamin D deficiency.

The Relationship of Falls With Achieved 25-Hydroxyvitamin D Levels From Vitamin D Supplementation: The STURDY Trial

Context

The Study to Understand Fall Reduction and Vitamin D in You (STURDY), a randomized trial enrolling older adults with low 25-hydroxyvitamin D [25(OH)D], demonstrated vitamin D supplementation ≥ 1000 IU/day did not prevent falls compared with 200 IU/day, with doses ≥ 2000 IU/day potentially showing safety concerns.

Objective

To examine associations of achieved and change in 25(OH)D concentrations after 3 months of vitamin D supplementation with fall risk.

Design

Observational analysis of trial data.

Setting

General community.

Participants

A total of 637 adults aged ≥ 70 with baseline 25(OH)D concentrations 10 to 29 ng/mL and elevated fall risk. Three-month on-treatment absolute 25(OH)D; absolute and relative changes from baseline.

Main Outcome Measures

Incident first fall (primary) and first consequential fall (injury or sought medical care) up to 24 months. Cox models were adjusted for sociodemographics, season, Short Physical Performance Battery, and body mass index.

Results

At baseline, mean (SD) age was 77.1 (5.4) years and 25(OH)D was 22.1 (5.1) ng/mL; 43.0% were women and 21.5% non-White. A total of 395 participants experienced ≥ 1 fall; 294 experienced ≥ 1 consequential fall. There was no association between absolute achieved 25(OH)D and incident first fall (30-39 vs < 30 ng/mL hazard ratio [HR], 0.93; 95% CI, 0.74-1.16; ≥40 vs < 30 ng/mL HR, 1.09; 95% CI, 0.82-1.46; adjusted overall P = 0.67), nor absolute or relative change in 25(OH)D. For incident consequential first fall, the HR (95% CI) comparing absolute 25(OH)D ≥ 40 vs < 30 ng/mL was 1.38 (0.99-1.90).

Conclusion

Achieved 25(OH)D concentration after supplementation was not associated with reduction in falls. Risk of consequential falls may be increased with achieved concentrations ≥ 40 ng/mL.

Trial Registration

ClinicalTrials.gov: NCT02166333.

The Effects of Four Doses of Vitamin D Supplements on Falls in Older Adults : A Response-Adaptive, Randomized Clinical Trial

BACKGROUND

Vitamin D supplementation may prevent falls in older persons, but evidence is inconsistent, possibly because of dosage differences.

OBJECTIVE

To compare the effects of 4 doses of vitamin D₃ supplements on falls.

DESIGN

2-stage Bayesian, response-adaptive, randomized trial. (ClinicalTrials.gov: NCT02166333).

SETTING

2 community-based research units.

PARTICIPANTS

688 participants, aged 70 years and older, with elevated fall risk and a serum 25-hydroxyvitamin D [25-(OH)D] level of 25 to 72.5 nmol/L.

INTERVENTION

200 (control), 1000, 2000, or 4000 IU of vitamin D₃ per day. During the dose-finding stage, participants were randomly assigned to 1 of the 4 vitamin D₃ doses, and the best noncontrol dose for preventing falls was determined. After dose finding, participants previously assigned to receive noncontrol doses received the best dose, and new enrollees were randomly assigned to receive 200 IU/d or the best dose.

MEASUREMENTS

Time to first fall or death over 2 years (primary outcome).

RESULTS

During the dose-finding stage, the primary outcome rates were higher for the 2000- and 4000-IU/d doses than for the 1000-IU/d dose, which was selected as the best dose (posterior probability of being best, 0.90). In the confirmatory stage, event rates were not significantly different between participants with experience receiving the best dose (events and observation time limited to the period they were receiving 1000 IU/d; n = 308) and those randomly assigned to receive 200 IU/d (n = 339) (hazard ratio [HR], 0.94 [95% CI, 0.76 to 1.15]; P = 0.54). Analysis of falls with adverse outcomes suggested greater risk in the experience-with-best-dose group versus the 200-IU/d group (serious fall: HR, 1.87 [CI, 1.03 to 3.41]; fall with hospitalization: HR, 2.48 [CI, 1.13 to 5.46]).

LIMITATIONS

The control group received 200 IU of vitamin D₃ per day, not a placebo. Dose finding ended before the prespecified thresholds for dose suspension and dose selection were reached.

CONCLUSION

In older persons with elevated fall risk and low serum 25-(OH)D levels, vitamin D₃ supplementation at doses of 1000 IU/d or higher did not prevent falls compared with 200 IU/d. Several analyses raised safety concerns about vitamin D₃ doses of 1000 IU/d or higher.

PRIMARY FUNDING SOURCE

National Institute on Aging.

The vitamin D and calcium controversy: an update

PURPOSE OF REVIEW

Calcium and vitamin D supplementation is widely recommended for prevention of falls and fracture, particularly in the elderly where calcium intakes and vitamin D levels are often inadequate. A number of meta-analyses have questioned the benefits of untargeted or 'holistic' supplementation for falls and fracture, and raised the possibility of adverse cardiovascular effects. This review provides an update on these controversies.

RECENT FINDINGS

Recent advances have largely centred around new trials of vitamin D and meta-analyses of published trials and observational studies. These articles have identified holistic vitamin D supplementation with or without calcium is unlikely to be an effective primary prevention strategy for falls or fracture. There has also been high-quality evidence that vitamin D, daily or as a bolus, does not reduce the risk of cardiovascular events.

SUMMARY

The benefits of vitamin D and calcium supplements for holistic fall and fracture prevention remain uncertain. Recent evidence supports the concept that high-dose vitamin D has adverse musculoskeletal effects. Future studies should focus on moderate daily doses. Finally, there remain inconsistent findings for adverse cardiovascular effects of calcium supplements with or without vitamin D. This uncertainty should be taken into account when evaluating the risk/benefits of supplementation.

Vitamin D and Falls in Older African American Women: The PODA Randomized Clinical Trial

BACKGROUND

Limited information is available on the influence of vitamin D on falls in older high-functioning black American women. Endocrine Society guidelines propose serum 25(OH)D levels over 30 ng/mL.

OBJECTIVE

To determine if maintenance of serum 25(OH)D above 30 ng/mL protects against falls.

DESIGN

The Physical Performance, Osteoporosis and Vitamin D in African American Women (PODA) trial had a prospective, randomized, placebo-controlled, double-dummy design with two arms: one with placebo and one with vitamin D₃ adjusted to maintain serum 25(OH)D above 30 ng/mL. The primary outcomes were the prevention of bone loss and the decline in physical performance.

PATIENTS

The target population was healthy black women older than 60 years with serum 25(OH)D between 8 and 26 ng/mL. The trial was 3 years in duration with a falls questionnaire administered every 3 months. A total of 260 women entered the study, and 184 completed the 3 years. Mean age was 68.2 years.

SETTING

Research center in an academic health center.

MAIN OUTCOMES MEASURE

Prevention of falls.

INTERVENTION

Participants were randomly assigned to placebo or active vitamin D. Vitamin D₃ dose was adjusted to maintain serum 25(OH)D above 30 ng/mL in the active group using a double-dummy design.

RESULTS

Baseline 25(OH)D was 22 ng/mL. Mean serum 25(OH)D reached 47 ng/mL in the active group compared with 21 ng/mL in the placebo group. There were 14.2% falls in the previous year recalled at baseline. During the study, 46% reported falling in the treatment group compared with 47% in the placebo group. There was no association of serum 25(OH)D or vitamin D dose with the risk of falling.

CONCLUSIONS

There is no benefit of maintaining serum 25(OH)D above 30 ng/mL compared with the Institute of Medicine recommendation (20 ng/mL) in preventing falls in healthy older black American women. J Am Geriatr Soc 67:1043-1049, 2019.

Assessing bone mineral changes in response to vitamin D supplementation using natural variability in stable isotopes of Calcium in Urine

Osteoporosis is a chronic disease of public health importance, particularly in low and middle income countries. Measuring the bone mineral balance (BMB) in a non-invasive manner, and its response to different interventions, is critical to the definition of optimal strategies for its prevention and management. In this study, we demonstrate the usefulness of natural variability in calcium isotopes (δ^44/40Ca) of urine and the derived BMB estimates as a biomarker of bone health and its responsiveness to interventions. Vitamin D₃ is commonly used as a supplement for the prevention and treatment of osteoporosis, along with calcium supplements. We studied the effect of a short term vitamin D₃ supplementation on changes in urine δ^44/40Ca and the derived BMB. δ^44/40Ca before and after the vitamin D₃ supplementation yielded a statistically significant change (p = 0.050) with a positive δ^44/40Ca enrichment. The mean derived BMB was net positive (0.04 ± 0.05) in comparison to a net negative value for the control group (−0.03 ± 0.01). These results indicate the potential usefulness of urinary natural δ^44/40Ca and the derived BMB, which, along with bone mineral density could be used as a sensitive marker for precision in the prevention and treatment of osteoporosis.

Rationale and design of the Study To Understand Fall Reduction and Vitamin D in You (STURDY): A randomized clinical trial of Vitamin D supplement doses for the prevention of falls in older adults

Prior evidence suggests that vitamin D supplementation may reduce fall risk, but existing data are inconsistent and insufficient to guide policy. We designed a two-stage Bayesian response-adaptive dose-finding and seamless confirmatory randomized trial of vitamin D supplementation to prevent falls. Up to 1200 community-dwelling persons, aged ≥70 years, of predominantly white and African-American race, with serum 25(OH)D concentrations of 10-29 ng/mL and at elevated fall risk, will be randomized to one of four vitamin D3 (cholecalciferol) supplement doses: 200 (control), 1000, 2000, or 4000 IU/day and treated for up to 2 years. Stage 1 is designed to identify the best of the non-control doses for fall prevention. If a best dose is selected, Stage 2 will start seamlessly, with enrollees assigned to control or the best dose in Stage 1 continuing on that dose unchanged, enrollees assigned to the two non-control, non-best doses in Stage 1 switched to the best dose, and new enrollees randomly assigned 1:1 to control or the best dose. In Stage 2, we will compare the control dose group to the best dose group to potentially confirm the efficacy of that dose for fall prevention. The primary outcome measure in both stages is time to first fall or death, whichever comes first. Falls are ascertained from calendars, scheduled interviews, or interim self-reports. Secondary outcome measures include time to each component of the composite primary outcome and gait speed. Additional outcomes include the Short Physical Performance Battery score, physical activity level (assessed by accelerometry), and frailty score.

CLINICAL TRIAL REGISTRATION

NCT02166333.