SynthesisPloS one2014
A case study of discordant overlapping meta-analyses: vitamin d supplements and fracture.
Synthesis in PloS one, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 24 papers, 6 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
24 citing papers in PubMed, 6 syntheses or guidelines pooled it, 59 citations in OpenAlex.
- The Lebanese GRADE-based vitamin D guidelines: a paradigm for the MENA region.Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2025Guideline
- How can clinicians choose between conflicting and discordant systematic reviews? A replication study of the Jadad algorithm.BMC medical research methodology · 2022Pooled it
- Vitamin D Supplementation and Fractures in Adults: A Systematic Umbrella Review of Meta-Analyses of Controlled Trials.The Journal of clinical endocrinology and metabolism · 2022Pooled it
- Dairy product consumption and risk of hip fracture: a systematic review and meta-analysis.BMC public health · 2018Pooled it
- Pooled it
- Use of existing systematic reviews for evidence assessments in infectious disease prevention: a comparative case study.Systematic reviews · 2016Pooled it
- A randomised controlled trial of low-dose aspirin for the prevention of fractures in healthy older people: protocol for the ASPREE-Fracture substudy.Injury prevention : journal of the International Society for Child and Adolescent Injury Prevention · 2016Trial
- Rethinking Vitamin D Deficiency: Controversies and Practical Guidance for Clinical Management.Nutrients · 2025Review
- Evidence-based health policy in Germany: lack of communication and coordination between academia and health authorities?Systematic reviews · 2023Article
- Article
- Effects of vitamin D with or without calcium on pathological ossification: A retrospective clinical study.Experimental and therapeutic medicine · 2022Article
- A meta-review of systematic reviews of lifestyle interventions for reducing gestational weight gain in women with overweight or obesity.Obesity reviews : an official journal of the International Association for the Study of Obesity · 2021Review
- Vitamin D status and complications, readmissions, and mortality after hip fracture.Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2021Article
- Concordance between systematic reviews of randomized controlled trials in assisted reproduction: an overview.Human reproduction open · 2020Review
- Overview of Systematic Reviews with Meta-Analysis Based on Randomized Controlled Trials of Balneotherapy and Spa Therapy from 2000 to 2019.International journal of general medicine · 2020Review
- Vibration of effects from diverse inclusion/exclusion criteria and analytical choices: 9216 different ways to perform an indirect comparison meta-analysis.BMC medicine · 2019Article
- Assessment of research waste part 1: an exemplar from examining study design, surrogate and clinical endpoints in studies of calcium intake and vitamin D supplementation.BMC medical research methodology · 2018Article
- Vitamin-D concentrations, cardiovascular risk and events - a review of epidemiological evidence.Reviews in endocrine & metabolic disorders · 2017Review
- Hypovitaminosis D Among Patients Admitted With Hip Fracture to a Level-1 Trauma Center in the Sunny Upper Egypt: Prevalence and Associated Correlates.Geriatric orthopaedic surgery & rehabilitation · 2016Article
- Errors in NOF meta-analyses of calcium and vitamin D supplements.Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2016Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
2 authors at 1 institution in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundOverlapping meta-analyses on the same topic are now very common, and discordant results often occur. To explore why discordant results arise, we examined a common topic for overlapping meta-analyses- vitamin D supplements and fracture. METHODS AND
findingsWe identified 24 meta-analyses of vitamin D (with or without calcium) and fracture in a PubMed search in October 2013, and analysed a sample of 7 meta-analyses in the highest ranking general medicine journals. We used the AMSTAR tool to assess the quality of the meta-analyses, and compared their methodologies, analytic techniques and results. Applying the AMSTAR tool suggested the meta-analyses were generally of high quality. Despite this, there were important differences in trial selection, data extraction, and analytical methods that were only apparent after detailed assessment. 25 trials were included in at least one meta-analysis. Four meta-analyses included all eligible trials according to the stated inclusion and exclusion criteria, but the other 3 meta-analyses "missed" between 3 and 8 trials, and 2 meta-analyses included apparently ineligible trials. The relative risks used for individual trials differed between meta-analyses for total fracture in 10 of 15 trials, and for hip fracture in 6 of 12 trials, because of different outcome definitions and analytic approaches. The majority of differences (11/16) led to more favourable estimates of vitamin D efficacy compared to estimates derived from unadjusted intention-to-treat analyses using all randomised participants. The conclusions of the meta-analyses were discordant, ranging from strong statements that vitamin D prevents fractures to equally strong statements that vitamin D without calcium does not prevent fractures.
conclusionsSubstantial differences in trial selection, outcome definition and analytic methods between overlapping meta-analyses led to discordant estimates of the efficacy of vitamin D for fracture prevention. Strategies for conducting and reporting overlapping meta-analyses are required, to improve their accuracy and transparency.
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What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.