Effect of metformin use on graft and patient survival in kidney transplant recipients with type 2 diabetes: a systematic review protocol.

INTRODUCTION: Metformin is a first-line antihyperglycaemic agent for type 2 diabetes (T2DM). In addition to glycaemic control, it offers benefits related to cardiovascular health, weight neutrality and metabolic syndrome. However, its benefits in kidney transplant recipients remain unclear as metformin use is controversial in this population due to a lack of evidence and there are recommendations against its use in patients with poor kidney function. Hence, we seek to describe a protocol for a systematic review, which will assess the impact of metformin use on graft survival and mortality in kidney transplant recipients. METHODS: This protocol was guided by the standards of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Protocols 2015. We will search empirical databases such as MEDLINE, Embase, Cochrane Library, CINAHL and Web of Science Core Collection for relevant studies conducted in kidney transplant recipients using metformin, which report outcomes related to graft and patient survival. All studies meeting these criteria in adults and published in English from inception to 2023 will be included in our review. We will employ the Cochrane Risk of Bias Tool 2 for randomised controlled trials and the Risk of Bias in Non-randomised Studies of Intervention for non-randomised studies. We will present our data and study characteristics in a table format and determine if a meta-analysis can be performed by clinical and methodological heterogeneity, using the I2 statistics. If a meta-analysis cannot be performed, we will provide a narrative synthesis of included studies using the Synthesis Without Meta-Analysis Reporting Guideline. ETHICS AND DISSEMINATION: Ethical approval will not be required for this review as the data used will be extracted from already published studies with publicly accessible data. As this study will assess the impact of metformin use on graft and patient survival in kidney transplant recipients, evidence gathered through it will be disseminated using traditional approaches that include open-access peer-reviewed publication, scientific presentations and a report. We will also disseminate our findings to appropriate academic bodies in charge of publishing guidelines related to T2DM and transplantation, as well as patient and research centred groups. PROSPERO REGISTRATION NUMBER: CRD42023421799.

The Leading Causes of Optic Disc Edema Seen in Tertiary Care, Academic Neuro-Ophthalmology Clinics.

BACKGROUND: Optic disc edema (ODE) is one of the most common reasons for referral to a neuro-ophthalmologist. There are various causes that require vastly different workup. Thus, differentiating among each cause is important. Our goal was to determine the causes of ODE and various clinical characteristics of consecutive patients with ODE presenting to neuro-ophthalmology clinics. METHODS: A retrospective review of consecutive patients with ODE over a period of 5 years were included. Fundus photographs were routinely obtained as part of clinical care. Clinical data including retinal nerve fiber layer thickness, best-corrected visual acuity, and visual field mean deviation were retrieved, and patients were grouped by etiology. RESULTS: A total of 654 patients (n = 462 or 70.6% women and 192 or 29.4% men) with ODE were included with a mean age of 41.2 ± 17.9 years. Female patients were significantly younger than male patients (mean age female participants: 38.7 years, male participants: 47.6; P < 0.001). The top 5 most common causes of ODE in our clinics were idiopathic intracranial hypertension (IIH; 351/654 or 53.7%), nonarteritic anterior ischemic optic neuropathy (NAION; 116/654 or 17.4%), non-IIH papilledema (71/654 or 10.9%), optic neuritis (ON; 46/654 or 7.0%), and uveitis (17/654 or 2.6%). When considering female-only patients, the top 3 causes of ODE were IIH, non-IIH papilledema, and NAION. Among male-only patients, the top 3 causes were NAION, IIH, and non-IIH. Among the top 5 causes of ODE, visual acuity was the worst at presentation in the ON group and the best in the patients with IIH. The Humphrey mean deviation was the worst in ON/NAION groups and best in IIH group. The ODE was most severe in patients with non-IIH papilledema and least severe in ON group. Non-IIH patients with papilledema were not significantly different in visual acuity and visual field parameters at presentation compared with patients with IIH papilledema. Patients with papilledema (both IIH and non-IIH etiologies) had significantly better visual function at presentation compared with other top causes of disc edema (P < 0.001). CONCLUSIONS: The most common cause of ODE seen in neuro-ophthalmology clinics was IIH, and these patients were more likely to present with preserved visual function. The higher prevalence of IIH was likely why most patients with ODE were women. Visual function at presentation was not able to differentiate the specific cause of papilledema; however, it was an important differentiating factor for all papilledema cases compared with all other causes of ODE including ON and NAION.

The Causes of Optic Disc Edema in Patients Presenting With Significantly Compromised Vision.

BACKGROUND: To evaluate the most common causes of optic disc edema (ODE) in patients with significantly compromised vision (initial best-corrected visual acuity [BCVA] of 20/400 or worse) at presentation. METHODS: Retrospective chart review over a 5-year period of consecutive patients presenting to tertiary neuro-ophthalmology clinics at the University of Toronto. RESULTS: A total of 656 patients with ODE were included, and 49 patients (7.47%) had an initial BCVA of 20/400 or worse. There were 54 eyes included at baseline and 49 eyes at final follow-up. There were 29 female and 20 male patients. The mean age at first visit across patients was 55.9 years. Female patients (n = 29) were significantly older than male patients (n = 20) (P < 0.05). The causes of ODE were optic neuritis (ON) (n = 22; 40.7%), nonarteritic anterior ischemic optic neuropathy (NAION) (n = 22; 40.7%), arteritic anterior ischemic optic neuropathy (AAION) (n = 5; 9.26%), uveitis-related (n = 3; 5.56%), papilledema from idiopathic intracranial hypertension (IIH) (n = 1; 1.85%), and Vogt-Koyanagi-Harada disease (n = 1; 1.85%). Initial BCVA was not significantly different between ON and NAION groups (P = 0.52); however, final BCVA was significantly better in the ON group (P < 0.0001). The mean initial BCVA was worst in the AAION group (2.62 ± 0.54 logarithm of the minimum angle of resolution). The most common cause of ODE in patients <40 years old was ON (83.3%), whereas the 2 most common causes in patients >80 were NAION (60%) and AAION (40%). In patients between the ages of 60-80, NAION (100%) was the only cause. CONCLUSIONS: Patients with ODE and poor vision at presentation represent a minority of cases seen in neuro-ophthalmology clinics (<10%). Optic neuritis and NAION are the 2 most common causes of ODE with poor vision at presentation. These findings are limited by a small sample size and potential sampling bias.