Epidemiological characteristics and prevalence rates of research reproducibility across disciplines: A scoping review of articles published in 2018-2019.

Background: Reproducibility is a central tenant of research. We aimed to synthesize the literature on reproducibility and describe its epidemiological characteristics, including how reproducibility is defined and assessed. We also aimed to determine and compare estimates for reproducibility across different fields. Methods: We conducted a scoping review to identify English language replication studies published between 2018 and 2019 in economics, education, psychology, health sciences, and biomedicine. We searched Medline, Embase, PsycINFO, Cumulative Index of Nursing and Allied Health Literature - CINAHL, Education Source via EBSCOHost, ERIC, EconPapers, International Bibliography of the Social Sciences (IBSS), and EconLit. Documents retrieved were screened in duplicate against our inclusion criteria. We extracted year of publication, number of authors, country of affiliation of the corresponding author, and whether the study was funded. For the individual replication studies, we recorded whether a registered protocol for the replication study was used, whether there was contact between the reproducing team and the original authors, what study design was used, and what the primary outcome was. Finally, we recorded how reproducibilty was defined by the authors, and whether the assessed study(ies) successfully reproduced based on this definition. Extraction was done by a single reviewer and quality controlled by a second reviewer. Results: Our search identified 11,224 unique documents, of which 47 were included in this review. Most studies were related to either psychology (48.6%) or health sciences (23.7%). Among these 47 documents, 36 described a single reproducibility study while the remaining 11 reported at least two reproducibility studies in the same paper. Less than the half of the studies referred to a registered protocol. There was variability in the definitions of reproduciblity success. In total, across the 47 documents 177 studies were reported. Based on the definition used by the author of each study, 95 of 177 (53.7%) studies reproduced. Conclusions: This study gives an overview of research across five disciplines that explicitly set out to reproduce previous research. Such reproducibility studies are extremely scarce, the definition of a successfully reproduced study is ambiguous, and the reproducibility rate is overall modest. Funding: No external funding was received for this work.

Vitamin D Supplementation for Benign Paroxysmal Positional Vertigo: A Systematic Review.

OBJECTIVE: Benign paroxysmal positional vertigo (BPPV) is commonly attributed to displaced otoconia. These have been shown to have biomineralization close to that of bone, and vitamin D deficiency has been associated with BPPV. We aim to systematically review the available literature on vitamin D supplementation and BPPV intensity and recurrence in adults. DATABASES REVIEWED: PubMed, MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), Current Controlled Trials, and ClinicalTrials.gov. METHODS: We systematically reviewed the available literature from 1947 to April 2020. The study protocol was registered in the PROSPERO database (trial registration: CRD42020183195). RESULTS: A total of 179 abstracts were identified and screened by two independent reviewers. Based on inclusion and exclusion criteria, six studies were selected and subjected to a quality assessment. In one randomized clinical trial (RCT), vitamin D supplementation was found to reduce annual recurrence rate of vertigo in patient with BPPV and subnormal serum vitamin D levels compared with placebo (odds ratio, 0.69; 95% confidence interval, 0.54-0.90). Non-RCTs demonstrated the possibility of a null effect in the random effects model (odds ratio, 0.08; 95% confidence interval, 0.00-1.56). The RCT considered as low risk of bias. All of the nonrandomized studies were assessed as serious risk of bias. CONCLUSIONS: The intervention studies identified consistently demonstrated a decrease in BPPV recurrence with supplementation of vitamin D in patients with subnormal vitamin D levels. Although there is a paucity of high-quality studies, the present literature does highlight a role for optimization of vitamin D levels in patients with BPPV.