COVID-19 and vitamin D (Co-VIVID study): a systematic review and meta-analysis of randomized controlled trials.

INTRODUCTION: Vitamin D levels have been reported to be associated with COVID-19 susceptibility, severity, and mortality events. We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the use of vitamin D intervention on COVID-19 outcomes. AREAS COVERED: Literature search was conducted using PubMed, Cochrane library, and ClinicalTrials.gov databases. We included RCTs reporting the use of vitamin D intervention to control/placebo group in COVID-19. The study was registered at PROSPERO: CRD42021271461. EXPERT OPINION: A total of 6 RCTs with 551 COVID-19 patients were included. The overall collective evidence pooling all the outcomes across all RCTs indicated the beneficial use of vitamin D intervention in COVID-19 (relative risk, RR = 0.60, 95% CI 0.40 to 0.92, Z = 2.33, p = 0.02, I2 = 48%). The rates of RT-CR positivity were significantly decreased in the intervention group as compared to the non-vitamin D groups (RR = 0.46, 95% CI 0.24 to 0.89, Z = 2.31, p = 0.02, I2 = 0%). Conclusively, COVID-19 patients supplemented with vitamin D are more likely to demonstrate fewer rates of ICU admission, mortality events, and RT-PCR positivity.

Maternal serum irisin levels in normotensive and preeclamptic pregnancies: a systematic review and meta-analysis.

BACKGROUND: Altered irisin levels have been reported in pregnancy-associated disorders, such as preeclampsia. OBJECTIVE: A systematic review and meta-analysis were conducted to evaluate the changes in maternal circulatory irisin levels in preeclampsia as compared to normotensive healthy pregnant controls. METHODS: Relevant studies were identified by searching PubMed and other databases. Random-effects model was used to obtain standardized mean differences (SMDs) and its 95% confidence intervals (CIs). The sub-group meta-regression analyses were conducted to explore heterogeneity. The presence of publication bias and the study robustness was tested using funnel plot and sensitivity analyses, respectively. RESULTS: This meta-analysis finally included 14 observations from eight studies. Compared with controls, preeclampsia patients showed significantly decreased serum irisin levels (SMD: -1.13; 95% CI: -1.63 to -0.62, p < .0001). The sub-group analysis showed that this decrease in irisin is regardless of body mass index (BMI) and gestational age of preeclampsia patients. The meta-regression analysis indicated that blood pressure is significantly associated with the observed results. There was no significant publication bias as indicated by the funnel plot analysis followed by Begg's (p = .35) and Egger's tests (p = .39). The sensitivity analysis indicated that no single study had a significant influence on the overall outcome, suggesting the robustness of this meta-analysis. CONCLUSIONS: This meta-analysis showed significantly decreased maternal serum irisin level in preeclampsia patients as compared to normotensive pregnant women. This study highlights the need for future studies evaluating the diagnostic utilities and associations of irisin with the fetal and neonatal outcomes in preeclampsia.

Effect of metformin intervention on circulating irisin levels in polycystic ovary syndrome: a systematic review and collaborative meta-analysis.

BACKGROUND: Irisin is an adipo-myokine with potential implications in metabolic disorders such as polycystic ovary syndrome (PCOS). Despite of a strong evidence showing increased irisin level in PCOS, there is no conclusive evidence on the effect of metformin intervention on circulatory irisin in PCOS. AIM: The aim of this meta-analysis was to compare the circulatory (serum/plasma) irisin levels before and after metformin intervention in subjects with PCOS. METHODS: Relevant studies were retrieved by online database and manual searching. The standardized mean differences (SMDs) with 95% confidence intervals (CIs) were obtained by a random-effects meta-analysis. A one-study leave-out sensitivity analysis was conducted to validate the overall obtained results. RESULTS: A total of five observations were included in this meta-analysis. The results based on random effects meta-analysis indicated that irisin levels were significantly decreased after metformin intervention as compared to the baseline pretreatment levels in PCOS (SMD: -1.00, 95% CI: -1.60 to -0.41, Z: 3.29, p = .001). The sensitivity analysis leaving-out a particular observation at a time and repeating the meta-analysis validated the robustness of the overall finding suggesting the significant effect of metformin treatment on irisin levels in PCOS. CONCLUSION: Circulating irisin levels were significantly decreased upon metformin intervention in PCOS patients. The higher pretreatment irisin levels in PCOS may recede once the altered metabolic state is restored upon metformin intervention. Well-designed randomized trials with large sample sizes are warranted to further substantiate the reported evidence reported and to establish the possible mechanisms.