Prediction of major postoperative events after non-cardiac surgery for people with kidney failure: derivation and internal validation of risk models.

BACKGROUND: People with kidney failure often require surgery and experience worse postoperative outcomes compared to the general population, but existing risk prediction tools have excluded those with kidney failure during development or exhibit poor performance. Our objective was to derive, internally validate, and estimate the clinical utility of risk prediction models for people with kidney failure undergoing non-cardiac surgery. DESIGN, SETTING, PARTICIPANTS, AND MEASURES: This study involved derivation and internal validation of prognostic risk prediction models using a retrospective, population-based cohort. We identified adults from Alberta, Canada with pre-existing kidney failure (estimated glomerular filtration rate [eGFR] < 15 mL/min/1.73m2 or receipt of maintenance dialysis) undergoing non-cardiac surgery between 2005-2019. Three nested prognostic risk prediction models were assembled using clinical and logistical rationale. Model 1 included age, sex, dialysis modality, surgery type and setting. Model 2 added comorbidities, and Model 3 added preoperative hemoglobin and albumin. Death or major cardiac events (acute myocardial infarction or nonfatal ventricular arrhythmia) within 30 days after surgery were modelled using logistic regression models. RESULTS: The development cohort included 38,541 surgeries, with 1,204 outcomes (after 3.1% of surgeries); 61% were performed in males, the median age was 64 years (interquartile range [IQR]: 53, 73), and 61% were receiving hemodialysis at the time of surgery. All three internally validated models performed well, with c-statistics ranging from 0.783 (95% Confidence Interval [CI]: 0.770, 0.797) for Model 1 to 0.818 (95%CI: 0.803, 0.826) for Model 3. Calibration slopes and intercepts were excellent for all models, though Models 2 and 3 demonstrated improvement in net reclassification. Decision curve analysis estimated that use of any model to guide perioperative interventions such as cardiac monitoring would result in potential net benefit over default strategies. CONCLUSIONS: We developed and internally validated three novel models to predict major clinical events for people with kidney failure having surgery. Models including comorbidities and laboratory variables showed improved accuracy of risk stratification and provided the greatest potential net benefit for guiding perioperative decisions. Once externally validated, these models may inform perioperative shared decision making and risk-guided strategies for this population.

Sequential measurement of the neurosensory retina in hypertensive disorders of pregnancy: a model of microvascular injury in hypertensive emergency.

Optical coherence tomography of the eye suggests the retina thins in normal pregnancy. Our objectives were to confirm and extend these observations to women with hypertensive disorders of pregnancy (HDP). Maternal demographics, clinical/laboratory findings and measurements of macular thickness were repeatedly collected at gestational ages <20 weeks, 20-weeks to delivery, at delivery and postpartum. The primary outcome was the change in macular thickness from non-pregnant dimensions in women with incident HDP compared to non-hypertensive pregnant controls. Secondary outcomes were the relationship(s) between mean arterial pressure (MAP) and macular response. Data show macular thicknesses diminished at <20 weeks gestation in each of 27 pregnancies ending in HDP (mean 3.94 µm; 95% CI 4.66, 3.21) and 11 controls (mean 3.92 µm; 5.05, 2.79; P < 0.001 versus non-pregnant dimensions in both; P = 0.983 HDP versus controls). This thinning response continued to delivery in all controls and in 7 women with HDP superimposed on chronic hypertension. Macular thinning was lost after 20 weeks gestation in the other 20 women with HDP. MAP at loss of macular thinning in women without prior hypertension (n = 12) was identical to MAP at enrollment. However, mean MAP subsequently rose 19 mmHg (15, 22) leading to de novo HDP in all 12 women. Loss of thinning leading to a rise in MAP was also observed in 8 of 15 women with HDP superimposed on chronic hypertension. We conclude the macula thins in most women in early pregnancy. Those who lose this early macular thinning response often develop blood pressure elevations leading to HDP.

Association of Kidney Function With Major Postoperative Events After Noncardiac Ambulatory Surgeries: A Population-Based Cohort Study.

OBJECTIVE: The aim of this study was to estimate the association between estimated glomerular filtration rate (eGFR) and acute myocardial infarction (AMI) or death after ambulatory noncardiac surgery. SUMMARY BACKGROUND DATA: People with chronic kidney disease (CKD) commonly undergo surgical procedures. Although most are performed in an ambulatory setting, the risk of major perioperative outcomes after ambulatory surgery for people with CKD is unknown. METHODS: In this retrospective population-based cohort study using administrative health data from Alberta, Canada, we included adults with measured preoperative kidney function undergoing ambulatory noncardiac surgery between April 1, 2005 and February 28, 2017. Participants were categorized into 6 eGFR categories (in mL/min/1.73m 2 )of ≥60 (G1-2), 45 to 59 (G3a), 30 to 44 (G3b), 15 to 29 (G4), <15 not receiving dialysis (G5ND), and those receiving chronic dialysis (G5D). The odds of AMI or death within 30 days of surgery were estimated using multivariable generalized estimating equation models. RESULTS: We identified 543,160 procedures in 323,521 people with a median age of 66 years (IQR 56-76); 52% were female. Overall, 2338 people (0.7%) died or had an AMI within 30 days of surgery. Compared with the G1-2 category, the adjusted odds ratio of death or AMI increased from 1.1 (95% confidence interval: 1.0-1.3) for G3a to 3.1 (2.6-3.6) for G5D. Emergency Department and Urgent Care Center visits within 30 days were frequent (17%), though similar across eGFR categories. CONCLUSIONS: Ambulatory surgery was associated with a low risk of major postoperative events. This risk was higher for people with CKD, which may inform their perioperative shared decision-making and management.

Perioperative management for people with kidney failure receiving dialysis: A scoping review.

BACKGROUND: People with kidney failure receiving dialysis (CKD-G5D) are more likely to undergo surgery and experience poorer postoperative outcomes than those without kidney failure. In this scoping review, we aimed to systematically identify and summarize perioperative strategies, protocols, pathways, and interventions that have been studied or implemented for people with CKD-G5D. METHODS: We searched MEDLINE, EMBASE, CINAHL Plus, Cochrane Database of Systematic Reviews, and Cochrane Controlled Trials registry (inception to February 2020), in addition to an extensive grey literature search, for sources that reported on a perioperative strategy to guide management for people with CKD-G5D. We summarized the overall study characteristics and perioperative management strategies and identified evidence gaps based on surgery type and perioperative domain. Publication trends over time were assessed, stratified by surgery type and study design. RESULTS: We included 183 studies; the most common study design was a randomized controlled trial (27%), with 67% of publications focused on either kidney transplantation or dialysis vascular access. Transplant-related studies often focused on fluid and volume management strategies and risk stratification, whereas dialysis vascular access studies focused most often on imaging. The number of publications increased over time, across all surgery types, though driven by non-randomized study designs. CONCLUSIONS: Despite many current gaps in perioperative research for patients with CKD-G5D, evidence generation supporting perioperative management is increasing, with recent growth driven primarily by non-randomized studies. Our review may inform organization of evidence-based strategies into perioperative care pathways where evidence is available while also highlighting gaps that future perioperative research can address.

Mortality and cardiovascular events in adults with kidney failure after major non-cardiac surgery: a population-based cohort study.

BACKGROUND: People with kidney failure have a high incidence of major surgery, though the risk of perioperative outcomes at a population-level is unknown. Our objective was to estimate the proportion of people with kidney failure that experience acute myocardial infarction (AMI) or death within 30 days of major non-cardiac surgery, based on surgery type. METHODS: In this retrospective population-based cohort study, we used administrative health data to identify adults from Alberta, Canada with major surgery between April 12,005 and February 282,017 that had preoperative estimated glomerular filtration rates (eGFRs) < 15 mL/min/1.73m2 or received chronic dialysis. The index surgical procedure for each participant was categorized within one of fourteen surgical groupings based on Canadian Classification of Health Interventions (CCI) codes applied to hospitalization administrative datasets. We estimated the proportion of people that had AMI or died within 30 days of the index surgical procedure (with 95% confidence intervals [CIs]) following logistic regression, stratified by surgery type. RESULTS: Overall, 3398 people had a major surgery (1905 hemodialysis; 590 peritoneal dialysis; 903 non-dialysis). Participants were more likely male (61.0%) with a median age of 61.5 years (IQR 50.0-72.7). Within 30 days of surgery, 272 people (8.0%) had an AMI or died. The probability was lowest following ophthalmologic surgery at 1.9% (95%CI: 0.5, 7.3) and kidney transplantation at 2.1% (95%CI: 1.3, 3.2). Several types of surgery were associated with greater than one in ten risk of AMI or death, including retroperitoneal (10.0% [95%CI: 2.5, 32.4]), intra-abdominal (11.7% [8.7, 15.5]), skin and soft tissue (12.1% [7.4, 19.1]), musculoskeletal (MSK) (12.3% [9.9, 15.5]), vascular (12.6% [10.2, 15.4]), anorectal (14.7% [6.3, 30.8]), and neurosurgical procedures (38.1% [20.3, 59.8]). Urgent or emergent procedures had the highest risk, with 12.1% experiencing AMI or death (95%CI: 10.7, 13.6) compared with 2.6% (1.9, 3.5) following elective surgery. CONCLUSIONS: After major non-cardiac surgery, the risk of death or AMI for people with kidney failure varies significantly based on surgery type. This study informs our understanding of surgery type and risk for people with kidney failure. Future research should focus on identifying high risk patients and strategies to reduce these risks.

Derivation and External Validation of a Risk Index for Predicting Acute Kidney Injury Requiring Kidney Replacement Therapy After Noncardiac Surgery.

Importance: Severe acute kidney injury (AKI) is a serious postoperative complication. A tool for predicting the risk of AKI requiring kidney replacement therapy (KRT) after major noncardiac surgery might assist with patient counseling and targeted use of measures to reduce this risk. Objective: To derive and validate a predictive model for AKI requiring KRT after major noncardiac surgery. Design, Setting, and Participants: In this prognostic study, 5 risk prediction models were derived and internally validated in a population-based cohort of adults without preexisting kidney failure who underwent noncardiac surgery in Alberta, Canada, between January 1, 2004, and December 31, 2013. The best performing model and corresponding risk index were externally validated in a population-based cohort of adults without preexisting kidney failure who underwent noncardiac surgery in Ontario, Canada, between January 1, 2007, and December 31, 2017. Data analysis was conducted from September 1, 2019, to May 31, 2021. Exposures: Demographic characteristics, surgery type, laboratory measures, and comorbidities before surgery. Main Outcomes and Measures: Acute kidney injury requiring KRT within 14 days after surgery. Discrimination was assessed using the C statistic; calibration was assessed using calibration intercept and slope. Logistic recalibration was used to optimize model calibration in the external validation cohort. Results: The derivation cohort included 92 114 patients (52.2% female; mean [SD] age, 62.3 [18.0] years), and the external validation cohort included 709 086 patients (50.8% female; mean [SD] age, 61.0 [16.0] years). A total of 529 patients (0.6%) developed postoperative AKI requiring KRT in the derivation cohort, and 2956 (0.4%) developed postoperative AKI requiring KRT in the external validation cohort. The following factors were consistently associated with the risk of AKI requiring KRT: younger age (40-69 years: odds ratio [OR], 2.07 [95% CI, 1.69-2.53]; <40 years: OR, 3.73 [95% CI, 2.61-5.33]), male sex (OR, 1.55; 95% CI, 1.28-1.87), surgery type (colorectal: OR, 4.86 [95% CI, 3.28-7.18]; liver or pancreatic: OR, 6.46 [95% CI, 3.85-10.83]; other abdominal: OR, 2.19 [95% CI, 1.66-2.89]; abdominal aortic aneurysm repair: OR, 19.34 [95% CI, 14.31-26.14]; other vascular: OR, 7.30 [95% CI, 5.48-9.73]; thoracic: OR, 3.41 [95% CI, 2.07-5.59]), lower estimated glomerular filtration rate (OR, 0.97; 95% CI, 0.97-0.97 per 1 mL/min/1.73 m2 increase), lower hemoglobin concentration (OR, 0.99; 95% CI, 0.98-0.99 per 0.1 g/dL increase), albuminuria (mild: OR, 1.88 [95% CI, 1.52-2.33]; heavy: OR, 3.74 [95% CI, 2.98-4.69]), history of myocardial infarction (OR, 1.63; 95% CI, 1.32-2.03), and liver disease (mild: OR, 2.32 [95% CI, 1.66-3.24]; moderate or severe: OR, 4.96 [95% CI, 3.58-6.85]). In external validation, a final model including these variables showed excellent discrimination (C statistic, 0.95; 95% CI, 0.95-0.96), with sensitivity of 21.2%, specificity of 99.9%, positive predictive value of 38.1%, and negative predictive value of 99.7% at a predicted risk threshold of 10% or greater. Conclusions and Relevance: The findings suggest that this risk model can predict AKI requiring KRT after noncardiac surgery using routine preoperative data. The model may be feasible for implementation in clinical perioperative risk stratification for severe AKI.

Estimated GFR and Incidence of Major Surgery: A Population-Based Cohort Study.

RATIONALE & OBJECTIVE: Kidney disease is associated with an increased risk for postoperative morbidity and mortality. However, the incidence of major surgery on a population level is unknown. We aimed to determine the incidence of major surgery by level of kidney function. STUDY DESIGN: Retrospective cohort study with entry from January 1, 2008, through December 31, 2009, and outcome surveillance from January 1, 2010, through December 31, 2016. SETTING & PARTICIPANTS: Population-based study using administrative health data from Alberta, Canada; adults with an outpatient serum creatinine measurement or receiving maintenance dialysis formed the study cohort. EXPOSURE: Participants were categorized into 6 estimated glomerular filtration rate (eGFR) categories: ≥60 (G1-G2), 45 to 59 (G3a), 30 to 44 (G3b), 15 to 29 (G4), and<15mL/min/1.73m2 with (G5D) and without (G5) dialysis. eGFR was examined as a time-varying exposure based on means of measurements within 3-month ascertainment periods throughout the study period. OUTCOME: Major surgery defined as surgery requiring admission to the hospital for at least 24 hours. ANALYTICAL APPROACH: Incidence rates (IRs) for overall major surgery were estimated using quasi-Poisson regression and adjusted for age, sex, income, location of residence, albuminuria, and Charlson comorbid conditions. Age- and sex-stratified IRs of 13 surgery subtypes were also estimated. RESULTS: 1,455,512 cohort participants were followed up for a median of 7.0 (IQR, 5.3) years, during which time 241,989 (16.6%) underwent a major surgery. Age and sex modified the relationship between eGFR and incidence of surgery. Men younger than 65 years receiving maintenance dialysis experienced the highest rates of major surgery, with an adjusted IR of 243.8 (95% CI, 179.8-330.6) per 1,000 person-years. There was a consistent trend of increasing surgery rates at lower eGFRs for most subtypes of surgery. LIMITATIONS: Outpatient preoperative serum creatinine measurement was necessary for inclusion and outpatient surgical procedures were not included. CONCLUSIONS: People with reduced eGFR have a significantly higher incidence of major surgery compared with those with normal eGFR, and age and sex modify this increased risk. This study informs our understanding of how surgical burden changes with differing levels of kidney function.

Perioperative management for people with chronic kidney disease receiving dialysis undergoing major surgery: a protocol for a scoping review.

INTRODUCTION: People with chronic kidney disease receiving dialysis (CKD G5D) have an increased risk of poor postoperative outcomes and a high incidence of major surgery. Despite the high burden of these combined risks, there is a paucity of evidence to support tailored perioperative strategies to manage this population. A comprehensive evidence synthesis would inform the management of these patients in the perioperative period and identify knowledge gaps. We describe a protocol for a scoping review of the literature to identify existing perioperative strategies, protocols, pathways and interventions for people with CKD G5D undergoing major surgery. METHODS AND ANALYSIS: We will conduct a scoping review in accordance with the Joanna Briggs Institute methodology and report per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for scoping reviews. In February 2020, we will complete our search of MEDLINE, EMBASE, CINAHL Plus, Cochrane Database of Systematic Reviews, and Cochrane Controlled Trials Registry for published literature from inception to present. All study types are eligible for inclusion, without language restriction. Studies reporting a perioperative intervention in adult patients with CKD G5D are eligible for inclusion. Studies in prevalent kidney transplant patients or patients with acute kidney injury, and studies that report on surgical approaches without consideration of perioperative management strategies, will be excluded. Reviewers will independently assess abstracts for all identified studies in duplicate, and again at the full-text stage. Following published literature searches, a search of the grey literature will be developed. We will extract and narratively report study, participant and intervention details. This will include a summary table outlining the strategies employed, organised into post hoc developed perioperative domains. ETHICS AND DISSEMINATION: Ethical considerations do not apply to this scoping review. Findings will be disseminated through relevant conference presentations and publications.

Hypertension Canada's 2017 Guidelines for Diagnosis, Risk Assessment, Prevention, and Treatment of Hypertension in Adults.

Hypertension Canada provides annually updated, evidence-based guidelines for the diagnosis, assessment, prevention, and treatment of hypertension. This year, we introduce 10 new guidelines. Three previous guidelines have been revised and 5 have been removed. Previous age and frailty distinctions have been removed as considerations for when to initiate antihypertensive therapy. In the presence of macrovascular target organ damage, or in those with independent cardiovascular risk factors, antihypertensive therapy should be considered for all individuals with elevated average systolic nonautomated office blood pressure (non-AOBP) readings ≥ 140 mm Hg. For individuals with diastolic hypertension (with or without systolic hypertension), fixed-dose single-pill combinations are now recommended as an initial treatment option. Preference is given to pills containing an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker in combination with either a calcium channel blocker or diuretic. Whenever a diuretic is selected as monotherapy, longer-acting agents are preferred. In patients with established ischemic heart disease, caution should be exercised in lowering diastolic non-AOBP to ≤ 60 mm Hg, especially in the presence of left ventricular hypertrophy. After a hemorrhagic stroke, in the first 24 hours, systolic non-AOBP lowering to < 140 mm Hg is not recommended. Finally, guidance is now provided for screening, initial diagnosis, assessment, and treatment of renovascular hypertension arising from fibromuscular dysplasia. The specific evidence and rationale underlying each of these guidelines are discussed.

The 2015 Canadian Hypertension Education Program recommendations for blood pressure measurement, diagnosis, assessment of risk, prevention, and treatment of hypertension.

The Canadian Hypertension Education Program reviews the hypertension literature annually and provides detailed recommendations regarding hypertension diagnosis, assessment, prevention, and treatment. This report provides the updated evidence-based recommendations for 2015. This year, 4 new recommendations were added and 2 existing recommendations were modified. A revised algorithm for the diagnosis of hypertension is presented. Two major changes are proposed: (1) measurement using validated electronic (oscillometric) upper arm devices is preferred over auscultation for accurate office blood pressure measurement; (2) if the visit 1 mean blood pressure is increased but < 180/110 mm Hg, out-of-office blood pressure measurements using ambulatory blood pressure monitoring (preferably) or home blood pressure monitoring should be performed before visit 2 to rule out white coat hypertension, for which pharmacologic treatment is not recommended. A standardized ambulatory blood pressure monitoring protocol and an update on automated office blood pressure are also presented. Several other recommendations on accurate measurement of blood pressure and criteria for diagnosis of hypertension have been reorganized. Two other new recommendations refer to smoking cessation: (1) tobacco use status should be updated regularly and advice to quit smoking should be provided; and (2) advice in combination with pharmacotherapy for smoking cessation should be offered to all smokers. The following recommendations were modified: (1) renal artery stenosis should be primarily managed medically; and (2) renal artery angioplasty and stenting could be considered for patients with renal artery stenosis and complicated, uncontrolled hypertension. The rationale for these recommendation changes is discussed.

The 2004 Canadian Hypertension Education Program recommendations for the management of hypertension: Part I--Blood pressure measurement, diagnosis and assessment of risk.

OBJECTIVE: To provide updated, evidence-based recommendations for the assessment of the diagnosis, cardiovascular risk and identifiable causes for adults with high blood pressure. OPTIONS: For persons in whom a high blood pressure value is recorded, the assignment of a diagnosis of hypertension is dependent on the appropriate measurement of blood pressure, the level of the blood pressure elevation and the duration of follow-up. In addition, the presence of concomitant vascular risk factors, target organ damage and established atherosclerotic diseases should be assessed to determine the urgency, intensity and type of treatment. For persons diagnosed as having hypertension, defining overall risk of adverse cardiovascular outcomes requires an assessment of concomitant vascular risk factors, including laboratory testing, a search for target organ damage and an assessment for modifiable causes of hypertension. Home and ambulatory blood pressure assessment and echocardiography are options for selected patients. OUTCOMES: The identification of persons at increased risk of adverse cardiovascular outcomes; the quantification of overall cardiovascular risk; and the identification of persons with potentially modifiable causes of hypertension. EVIDENCE: Medline searches were conducted from November 2001, one year before the period of the last revision of the Canadian recommendations for the management of hypertension, to October 2003. Reference lists were scanned, experts were polled, and the personal files of subgroup members and authors were used to identify other studies. Identified articles were reviewed and appraised using prespecified levels of evidence by content experts and methodological experts. VALUES: A high value was placed on the identification of persons at increased risk of cardiovascular morbidity and mortality, and persons with identifiable and potentially modifiable causes of hypertension. BENEFITS, HARMS AND COSTS: The identification of persons at higher risk of cardiovascular disease will permit counselling for lifestyle maneuvers and introduction of antihypertensive drugs to reduce blood pressure for patients with sustained hypertension. The identification of specific causes of hypertension may permit the use of cause-specific interventions. For certain subgroups of patients and specific classes of drugs, blood pressure lowering has been associated with reduced cardiovascular morbidity and/or mortality. RECOMMENDATIONS: The document contains recommendations for blood pressure measurement, diagnosis of hypertension and assessment of cardiovascular risk for adults with high blood pressure. These include the accurate measurement of blood pressure, criteria for diagnosis of hypertension, and recommendations for follow-up, assessment of overall cardiovascular risk, routine and optional laboratory testing, assessment for renovascular and endocrine causes, home and ambulatory blood pressure monitoring, and the role of echocardiography for those with hypertension. VALIDATION: All recommendations were graded according to strength of evidence and voted on by the Canadian Hypertension Education Program Evidence-Based Recommendations Task Force. Only the recommendations that achieved high levels of consensus are reported. These guidelines will be updated annually.