Why hold metformin before contrast

For example, discontinuation of metformin may result in hyperglycemia and the need for the institution of insulin, as well as weight gain [ 9 ]. We have two overall objectives in this systematic review: firstly, what is the effect of holding RAS blockers, NSAIDs, diuretics or metformin before the administration of contrast media on the risk of CI-AKI and related renal complication in patients who undergo contrast procedures?

Secondly, what are the frequencies of clinical adverse events occurring after withdrawal of RAS blockers, NSAIDs, diuretics, or metformin prior to the administration of contrast media in patients who undergo contrast procedures?

Specific objectives are to summarize available evidence on 1 the risk of CI-AKI and other clinical outcomes [including renal outcomes, such as the need for renal replacement therapy RRT , prolonged hospitalization, lactic acidosis, and death] amongst patients who underwent contrast procedures in whom these drug classes specifically RAS blockers, NSAIDs, diuretics, and metformin were withheld compared to those in whom they were not and 2 the incidence of adverse effects occurring after withholding RAS blockers, NSAIDs, diuretics, or metformin prior to contrast administration amongst patients who underwent contrast procedures.

This systematic review will be performed to assess the effect of medication restriction before the administration of contrast material on the risk of subsequent CI-AKI and other clinical outcomes. The review will include randomized controlled trials, observational studies, case reports, and case series. The patient population will also be one receiving at least one of the drug classes to be studied i. The exposure to be assessed will be withholding of the drug prior to the contrast procedure.

The drugs to be studied include RAS blockade renin inhibitor and aliskerin; ACE-I: captopril, cilazapril, enalapril, fosinopril, lisinopril, perindopril, quinapril, ramipril, trandolapril, benazepril, and moexipril; ARBs: candesartan, valsartan, eprosartan, irbesartan, losartan, telmisartan, and olmesartan , NSAIDs aspirin, ibuprofen, and naproxen , loop diuretics furosemide, bumetanide, ethacrynic acid, and torsemide , thiazide diuretics hydrochlorothiazide, chlorothiazide, methylclothiazide, and bendrofluazide , thiazide-like diuretics metolazone, chlorthalidone, and indapamide , and metformin.

In studies where the drugs of interest are not withheld in patients prior to contrast procedures, a comparison will be made between patients who are administered the drugs of interest RAS blockade, diuretics, NSAIDs, or metformin before undergoing contrast procedures and patients who are not administered the drugs prior to contrast procedures, thus serving as controls.

The search terms were adapted for the different databases using a combination of Medical Subject Heading MeSH and relevant keywords contained in titles and abstracts. The literature search will be extended by 1 reviewing the bibliographic reference lists of studies selected from electronic databases and 2 identifying relevant abstracts from relevant professional society meetings from the fields of nephrology and cardiology.

Articles will be imported into Microsoft Excel, and duplicates will be removed. Two reviewers BL and OM will independently screen the titles and abstracts of each potential relevant article to determine whether they meet the inclusion criteria. If an abstract is absent, the full text will be reviewed. Articles that meet the inclusion criteria will have their full texts obtained. Each independent reviewer will then screen the full texts of potentially relevant articles.

Any disagreements between the independent reviewers will be mediated by a third reviewer SH. Reviewers will not be blinded to the authors or journals when screening articles. A data extraction template will be created by the principal investigator SH in Microsoft Excel and modified by feedback from two independent reviewers BL and OM to ensure that complete data is obtained.

Reviewers will not be blinded to the authors or journals during this process. CI-AKI is a sudden deterioration in renal function following the recent intravascular administration of a contrast medium in the absence of another nephrotoxic event. The secondary outcome of interest will be the frequency of adverse effects occurring after withholding the drugs. More specifically, the incidence of the following events will be reported: 1 drugs not being restarted and 2 rebound hypertension, hyperglycemia, weight gain, or pain.

Additional outcomes that will be studied include other renal outcomes, such as the need for RRT and persistent renal dysfunction, as well as other morbidity outcomes, such as prolonged hospitalization, risk of lactic acidosis, and mortality outcome. The study quality and the presence of potential bias within individual studies will be done at both the outcome level and the study level.

Two reviewers BL and OM will complete the assessment independently. A table comprised of study characteristics will illustrate the results from this methodology quality assessment. Study data will be quantitatively synthesized by first assessing heterogeneity to examine whether the estimates from included studies could be pooled.

RCTs and observational studies will be pooled separately. All analysis will be performed using the Comprehensive Meta-analysis software version 2. In cases where quantitative synthesis is not appropriate because it is not possible to conduct meta-analysis due to the heterogeneity of estimates reported by studies, a qualitative narrative synthesis of the evidence will be performed.

This will summarize the key characteristics of the studies included i. Additional analyses that will be performed include sensitivity and multivariate meta-regression analyses in order to assess the effects of some clinical factors and socio-demographic characteristics reported in included studies i.

The purpose of this systematic review is to identify, collect, and summarize the current evidence on the discontinuation of drugs prior to contrast procedures and its effect on CI-AKI and other clinical outcomes, such as the need for RRT, prolonged hospitalization, lactic acidosis, and death. More specifically, this study will aim to compare patients in whom these drugs were withheld and those in whom they were continued, prior to the exposure of contrast material, in order to better assess the risk of CI-AKI and other clinically important outcomes.

An analysis of the incidence of adverse effects, which include drugs not being restarted, rebound, hypertension, and hyperglycemia or weight gain, occurring following the event of withholding these drugs will also be done. The information from this systematic review will help advice cardiologists, radiologists, nephrologists, and other clinicians of the current evidence for interventions to prevent CI-AKI.

In addition, this synthesis will enable clinicians to have a better understanding about which drugs should be stopped, when they should be stopped, and when they should be restarted after exposure to contrast material.

This will allow patients at risk of developing CI-AKI or other adverse clinical outcomes to receive the proper care and treatment. These findings will ultimately provide a robust base to update clinical guidelines with new evidence-based recommendations and establish a strong research base for future studies in this subject field. Katzberg RW, Haller C. Contrast-induced nephrotoxicity: clinical landscape.

Kidney Int Suppl. Outcome definitions in non-dialysis intervention and prevention trials in acute kidney injury AKI. Nephrol Dial Transplant. Article PubMed Google Scholar. Section 4: contrast-induced AKI. Article Google Scholar. American Journal of Medicine74 2 pp — , Date of Publication: 2 — Owen R, Hiremath, S.

Can Assoc Radiol J , in press. Pototski M, Amenabar JM. Dental management of patients receiving anticoagulation or antiplatelet treatment. J Oral Sci. Discontinuation of and changes in drug therapy for hypertension among newly-treated patients: a population-based study in Italy.

J Hypertens. Discontinuation of metformin in the setting of coronary angiography: clinical uncertainty amongst physicians reflecting a poor evidence base. Eur Secur. Google Scholar. PLoS Med. PRESS peer review of electronic search strategies: guideline statement. J Clin Epidemiol. Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury. Crit Care. DerSimonian R, Laird N. Meta-analysis in clinical trials. Control Clin Trials. Meta-analysis of observational studies in epidemiology: a proposal for reporting.

Until recently, it is for these reasons that all patients discontue metformin-containg products following iodinated contrast administration. The mechanism is felt to be due to a combination of lactic acid formation from glucose in the splanchnic bed, intracellular shift from aerobic to anaerobic metabolism, and inhibition of gluconeogenesis from lactate via inhibition of pyruvate carboxylase — the rate limiting enzyme in the formation of glucose from lactate.

Fortunately, there has been reconsideration and re-evauation of the true risk factors for developing MALA. Furthermore, there is controversy regarding the causal relationship between diabetes and MALA i. This has lead to a much more appropriate and evidenced based approach to management of metformin-treated patients undergoing iodinated contrast examinations.

What does this mean for metformin-treated patients in need of an iodinated contrast exam? For nearly all patients in the outpatient setting, we will no longer need to withold metformin following iodinated contrast administration. Metformin is a medication used to treat non-insulin dependent diabetes mellitus. The most significant adverse effect of metformin therapy is the potential for the development of metformin-associated lactic acidosis. This condition is extremely rare, and seems to occur only when one or more contraindications for the drug are overlooked.