Association between annual exposure to air pollution and systolic blood pressure among adolescents in Montréal, Canada. / Association entre l'exposition annuelle à la pollution atmosphérique et la pression artérielle systolique chez des adolescents à Montréal (Canada).

INTRODUCTION: In adults, chronic exposure to air pollution is associated with elevated blood pressure, but few studies have examined this relationship in youth. We investigated the association between annual ambient concentrations of air pollutants (fine particulate matter [PM2.5] and nitrogen dioxide [NO2]) and systolic blood pressure (SBP) among adolescents in Montréal, Canada. METHODS: Participants were students aged 15 to 17 years who provided SBP and residential postal code data in 2004/05 through their enrolment in the Nicotine Dependence in Teens study. Annual estimates for 2004 of residential exposure to NO2 and PM2.5 were provided by the Canadian Urban Environmental Health Research Consortium and linked to participants' residential postal code. Elevated SBP was defined as SBP ≥ 90th percentile adjusted for age, sex and height. Logistic regression was used to estimate odds ratios and 95% confidence intervals (CIs) for each pollutant with respect to elevated SBP, adjusted for relevant confounders. RESULTS: The sample consisted of 508 adolescents (mean age: 16.9, 46% male); 4% had elevated SBP. Although estimates were not statistically significant, there were generally modest positive associations between pollutant levels and SBP. The adjusted prevalence odds ratio of elevated SBP was 1.33 (95% CI: 0.64, 3.05) for every interquartile range (IQR) increase in residential PM2.5 levels (2.1µg/m3). Similarly, the adjusted prevalence odds ratio of elevated SBP was 1.17 (95% CI: 0.47, 2.70) for every IQR increase in residential NO2 levels (10.2 ppb). CONCLUSION: Findings support a possible relationship between exposure to air pollutants and increased SBP in adolescents, warranting further investigation for this important public health concern.

Impact of the Magnitude and Timing of Fluid Overload on Outcomes in Critically Ill Children: A Report From the Multicenter International Assessment of Worldwide Acute Kidney Injury, Renal Angina, and Epidemiology (AWARE) Study.

OBJECTIVES: With the recognition that fluid overload (FO) has a detrimental impact on critically ill children, the critical care nephrology community has focused on identifying clinically meaningful targets for intervention. The current study aims to evaluate the epidemiology and outcomes associated with FO in an international multicenter cohort of critically ill children. The current study also aims to evaluate the association of FO at predetermined clinically relevant thresholds and time points (FO ≥ 5% and FO ≥ 10% at the end of ICU days 1 and 2) with outcomes. DESIGN: Prospective cohort study. SETTING: Multicenter, international collaborative of 32 pediatric ICUs. PATIENTS: A total of 5,079 children and young adults admitted consecutively to pediatric ICUs as part of the Assessment of the Worldwide Acute Kidney Injury, Renal Angina and Epidemiology Study. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The FO thresholds at the time points of interest occurred commonly in the cohort (FO ≥ 5%Day1 in 38.1% [ n = 1753], FO ≥ 10%Day1 in 11.7% [ n = 537], FO ≥ 5%Day2 in 53.3% [ n = 1,539], FO ≥ 10%Day2 in 25.1% [ n = 724]). On Day1, multivariable modeling demonstrated that FO ≥ 5% was associated with fewer ICU-free days, and FO ≥ 10% was associated with higher mortality and fewer ICU and ventilator-free days. On multivariable modeling, FO-peak, Day2 FO ≥ 5%, and Day2 FO ≥ 10% were associated with higher mortality and fewer ICU and ventilator-free days. CONCLUSIONS: This study found that mild-to-moderate FO as early as at the end of ICU Day1 is associated with adverse outcomes. The current study fills an important void in the literature by identifying critical combinations of FO timing and quantity associated with adverse outcomes (FO ≥ 5%Day1, FO ≥10%Day1, FO ≥ 5%Day2, and FO ≥ 10%Day2). Those novel findings will help guide the development of interventional strategies and trials targeting the treatment and prevention of clinically relevant FO.

Long-term Health Care Utilization and Associated Costs After Dialysis-Treated Acute Kidney Injury in Children.

RATIONALE & OBJECTIVE: Acute kidney injury (AKI) is common among hospitalized children and is associated with increased hospital length of stay and costs. However, there are limited data on postdischarge health care utilization after AKI hospitalization. Our objectives were to evaluate health care utilization and physician follow-up patterns after dialysis-treated AKI in a pediatric population. STUDY DESIGN: Retrospective cohort study, using provincial health administrative databases. SETTING & PARTICIPANTS: All children (0-18 years) hospitalized between 1996 and 2017 in Ontario, Canada. Excluded individuals comprised non-Ontario residents; those with metabolic disorders or poisoning; and those who received dialysis or kidney transplant before admission, a kidney transplant by 104 days after discharge, or were receiving dialysis 76-104 days from dialysis start date. EXPOSURE: Episodes of dialysis-treated AKI, identified using validated health administrative codes. AKI survivors were matched to 4 hospitalized controls without dialysis-treated AKI by age, sex, and admission year. OUTCOME: Our primary outcome was postdischarge hospitalizations, emergency department visits, and outpatient physician visits. Secondary outcomes included outpatient visits by physician type and composite health care costs. ANALYTICAL APPROACH: Proportions with≥1 event and rates (per 1,000 person-years). Total and median composite health care costs. Adjusted rate ratios using negative binomial regression models. RESULTS: We included 1,688 pediatric dialysis-treated AKI survivors and 6,752 matched controls. Dialysis-treated AKI survivors had higher rehospitalization and emergency department visit rates during the analyzed follow-up periods (0-1, 0-5, and 0-10 years postdischarge, and throughout follow-up), and higher outpatient visit rates in the 0-1-year follow-up period. The overall adjusted rate ratio for rehospitalization was 1.46 (95% CI, 1.25-1.69; P<0.0001) and for outpatient visits was 1.16 (95% CI, 1.09-1.23; P=0.01). Dialysis-treated AKI survivors also had higher health care costs. Nephrologist follow-up was infrequent among dialysis-treated AKI survivors (18.6% by 1 year postdischarge). LIMITATIONS: Potential miscoding of study exposures or outcomes. Residual uncontrolled confounding. Data for health care costs and emergency department visits was unavailable before 2006 and 2001, respectively. CONCLUSIONS: Dialysis-treated AKI survivors had greater postdischarge health care utilization and costs versus hospitalized controls. Strategies are needed to improve follow-up care for children after dialysis-treated AKI to prevent long-term complications.

Development of a patient-reported outcome measure for the assessment of symptom burden in pediatric chronic kidney disease (PRO-Kid).

BACKGROUND: Chronic kidney disease (CKD) and kidney failure in childhood are associated with significant and life-altering morbidities and lower quality of life. Emerging evidence suggests that management should be guided in part by symptom burden; however, there is currently no standardized assessment tool for quantifying symptom burden in this pediatric population. This study aimed to develop and refine a patient-reported symptom assessment tool for children with CKD/kidney failure (PRO-Kid), to evaluate the frequency and impact of symptoms. METHODS: This was a prospective observational study of children and caregivers of children with CKD/kidney failure at two Canadian pediatric care centers. Building on previously published patient-reported outcome measures (PROs) for the assessment of symptom burden in other populations, we drafted a 13-item questionnaire. Cognitive interviews were performed with children and caregivers of children with CKD/kidney failure to iteratively refine the questionnaire. RESULTS: Twenty-four participants completed cognitive interviewing (11 children, 13 caregivers). The most common symptoms endorsed were feeling left out, feeling sad/depressed, inability to focus, tiredness, nausea, vomiting, not wanting to eat, and changes in the taste of food. Feeling left out was added to the questionnaire as almost all participants voiced this as a frequent and impactful symptom, resulting in a 14-item questionnaire. CONCLUSIONS: PRO-Kid is the first pediatric CKD/kidney failure-specific PRO tool to assess symptom burden. Future work should validate this tool in a larger cohort so that it may be used to improve the care of children living with CKD/kidney failure. A higher resolution version of the Graphical abstract is available as Supplementary information.

24-hour ambulatory blood pressure monitoring 9 years after pediatric cardiac surgery: a pilot and feasibility study.

BACKGROUND: Children undergoing cardiac surgery are at risk of high blood pressure (BP), a risk factor for cardiovascular and kidney disease. Twenty-four-hour ambulatory BP monitoring (ABPM) is a reference standard hypertension (HTN) test. Little data exist on ABPM abnormalities in children several years post cardiac surgery. This study aimed to (a) determine ABPM feasibility; (b) describe and compare ABPM measures and abnormalities (percent load, masked HTN [MH]; non-dipping, mean systolic/diastolic BP > 95th percentile; pre-HTN (ABPM); white-coat HTN [WCH]) to casual BP; and (c) compare BP in patients with and without acute kidney injury (AKI). METHODS: Prospective, follow-up pilot study of children (0-18 years) who underwent cardiac surgery from 2007 to 2009 at Montreal Children's Hospital. We recorded if participants had post-operative AKI and assessed the following outcomes at 9-year follow-up: casual BP classified by three single-visit measures (normal; elevated BP [eBPSingleVisit]; HTNSingleVisit); ABPM. Bivariable analyses were used to compare characteristics between groups. RESULTS: Twenty-three patients (median [interquartile range], 8.6 [8.0, 9.0] years post cardiac surgery) were included; 16 (70%) male. Six participants (26%) had eBPSingleVisit or higher. On ABPM, 11 (48%) had ≥ 1 abnormality: 9 (39%) had non-dipping; 3 (13%) had pre-HTN; 3 (13%) had WCH; none had HTN or MH. There were no differences in ABPM according to AKI status. CONCLUSION: Our pilot study determined that ABPM was feasible in children years after cardiac surgery and frequently identified ABPM abnormalities. Future research in larger populations is needed to define specific risk factors for HTN in children after cardiac surgery.

Post-Acute Kidney Injury Proteinuria and Subsequent Kidney Disease Progression: The Assessment, Serial Evaluation, and Subsequent Sequelae in Acute Kidney Injury (ASSESS-AKI) Study.

Importance: Among patients who had acute kidney injury (AKI) during hospitalization, there is a need to improve risk prediction such that those at highest risk for subsequent loss of kidney function are identified for appropriate follow-up. Objective: To evaluate the association of post-AKI proteinuria with increased risk of future loss of renal function. Design, Setting, and Participants: The Assessment, Serial Evaluation, and Subsequent Sequelae in Acute Kidney Injury (ASSESS-AKI) Study was a multicenter prospective cohort study including 4 clinical centers in North America included 1538 patients enrolled 3 months after hospital discharge between December 2009 and February 2015. Exposures: Urine albumin-to-creatinine ratio (ACR) quantified 3 months after hospital discharge. Main Outcomes and Measures: Kidney disease progression defined as halving of estimated glomerular filtration rate (eGFR) or end-stage renal disease. Results: Of the 1538 participants, 769 (50%) had AKI durring hospitalization. The baseline study visit took place at a mean (SD) 91 (23) days after discharge. The mean (SD) age was 65 (13) years; the median eGFR was 68 mL/min/1.73 m2; and the median urine ACR was 15 mg/g. Overall, 547 (37%) study participants were women and 195 (13%) were black. After a median follow-up of 4.7 years, 138 (9%) participants had kidney disease progression. Higher post-AKI urine ACR level was associated with increased risk of kidney disease progression (hazard ratio [HR], 1.53 for each doubling; 95% CI, 1.45-1.62), and urine ACR measurement was a strong discriminator for future kidney disease progression (C statistic, 0.82). The performance of urine ACR was stronger in patients who had had AKI than in those who had not (C statistic, 0.70). A comprehensive model of clinical risk factors (eGFR, blood pressure, and demographics) including ACR provided better discrimination for predicting kidney disease progression after hospital discharge among those who had had AKI (C statistic, 0.85) vs those who had not (C statistic, 0.76). In the entire matched cohort, after taking into account urine ACR, eGFR, demographics, and traditional chronic kidney risk factors determined 3 months after discharge, AKI (HR, 1.46; 95% CI, 0.51-4.13 for AKI vs non-AKI) or severity of AKI (HR, 1.54; 95% CI, 0.50-4.72 for AKI stage 1 vs non-AKI; HR, 0.56; 95% CI, 0.07-4.84 for AKI stage 2 vs non-AKI; HR, 2.24; 95% CI, 0.33-15.29 for AKI stage 3 vs non-AKI) was not independently associated with more rapid kidney disease progression. Conclusions and Relevance: Proteinuria level is a valuable risk-stratification tool in the post-AKI period. These results suggest there should be more widespread and routine quantification of proteinuria after hospitalized AKI.

Identifying Important Outcomes for Young People With CKD and Their Caregivers: A Nominal Group Technique Study.

RATIONALE & OBJECTIVE: Chronic kidney disease (CKD) has wide-ranging and long-term consequences for young people and their families. The omission of outcomes that are important to young people with CKD and their caregivers limits knowledge to guide shared decision making. We aimed to identify the outcomes that are important to young people with CKD and their caregivers. STUDY DESIGN: We used the nominal group technique whereby participants identified and ranked outcomes and explained their priorities. SETTINGS & PARTICIPANTS: Young people with CKD (stages 1-5, dialysis, or transplantation) and their caregivers were purposively sampled from 6 centers across Australia, the United States, and Canada. ANALYTICAL APPROACH: Importance scores were calculated (scale of 0-1), and qualitative data were analyzed thematically. RESULTS: 34 patients (aged 8-21 years) and 62 caregivers participated in 16 groups and identified 48 outcomes. The 5 highest ranked outcomes for patients were survival (importance score, 0.25), physical activity (0.24), fatigue (0.20), lifestyle restrictions (0.20), and growth (0.20); and for caregivers, kidney function (0.53), survival (0.28), infection (0.22), anemia (0.20), and growth (0.17). 12 themes were identified reflecting their immediate and current priorities (wanting to feel normal, strengthening resilience, minimizing intrusion into daily life, imminent threats to life, devastating family burdens, and seeking control over health) and considerations regarding future impacts (protecting health/development, remaining hopeful, concern for limited opportunities, prognostic uncertainty, dreading painful and invasive procedures, and managing expectations). LIMITATIONS: Only English-speaking participants were recruited. CONCLUSIONS: Kidney function, infection, survival, and growth were the highest priorities for patients with CKD and their caregivers. Young people with CKD also prioritized highly the outcomes that directly affected their lifestyle and sense of normality, while caregiver's highest priorities concerned the long-term health of their child, current health problems, and the financial and family burdens of caring for a child with CKD.

Optimizing the AKI definition during first postnatal week using Assessment of Worldwide Acute Kidney Injury Epidemiology in Neonates (AWAKEN) cohort.

BACKGROUND: Neonates with serum creatinine (SCr) rise ≥0.3 mg/dL and/or ≥50% SCr rise are more likely to die, even when controlling for confounders. These thresholds have not been tested in newborns. We hypothesized that different gestational age (GA) groups require different SCr thresholds. METHODS: Neonates in Assessment of Worldwide Acute Kidney Epidemiology in Neonates (AWAKEN) with ≥1 SCr on postnatal days 1-2 and ≥1 SCr on postnatal days 3-8 were assessed. We compared the mortality predictability of SCr absolute (≥0.3 mg/dL) vs percent (≥50%) rise. Next, we determine usefulness of combining absolute with percent rise. Finally, we determined the optimal absolute, percent, and maximum SCr thresholds that provide the highest mortality area under curve (AUC) and specificity for different GA groups. RESULTS: The ≥0.3 mg/dL rise outperformed ≥50% SCr rise. Addition of percent rise did not improve mortality predictability. The optimal SCr thresholds to predict AUC and specificity were ≥0.3 and ≥0.6 mg/dL for ≤29 weeks GA, and ≥0.1 and ≥0.3 mg/dL for >29 week GA. The maximum SCr value provides great specificity. CONCLUSION: Unique SCr rise cutoffs for different GA improves outcome prediction. Percent SCr rise does not add value to the neonatal AKI definition.

Child and Parental Perspectives on Communication and Decision Making in Pediatric CKD: A Focus Group Study.

BACKGROUND & OBJECTIVES: Effective communication and shared decision making improve quality of care and patient outcomes but can be particularly challenging in pediatric chronic disease because children depend on their parents and clinicians to manage complex health care and developmental needs. We aimed to describe the perspectives of children with chronic kidney disease (CKD) and their parents with regard to communication and decision making. STUDY DESIGN: Qualitative study. SETTING & PARTICIPANTS: Children with CKD (n=34) and parents (n=62) from 6 centers across 6 cities in Australia, Canada, and the United States participated in 16 focus groups. ANALYTICAL APPROACH: Transcripts were analyzed thematically. RESULTS: We identified 4 themes: (1) disempowered by knowledge imbalance (unprepared and ill-informed, suspicion of censorship, and inadequacy as technicians), (2) recognizing own expertise (intuition and instinct unique to parental bond, emerging wisdom and confidence, identifying opportunities for control and inclusion, and empowering participation in children), (3) striving to assert own priorities (negotiating broader life impacts, choosing to defer decisional burden, overprotected and overruled, and struggling to voice own preferences), and (4) managing child's involvement (respecting child's expertise, attributing "risky" behaviors to rebellion, and protecting children from illness burden). LIMITATIONS: Only English-speaking participants were recruited, which may limit the transferability of the findings. We collected data from child and parent perspectives; however, clinician perspectives may provide further understanding of the difficulties of communication and decision making in pediatrics. CONCLUSIONS: Parents value partnership with clinicians and consider long-term and quality-of-life implications of their child's illness. Children with CKD want more involvement in treatment decision making but are limited by vulnerability, fear, and uncertainty. There is a need to support the child to better enable him or her to become a partner in decision making and prepare him or her for adulthood. Collaborative and informed decision making that addresses the priorities and concerns of both children and parents is needed.

An assessment of dialysis provider's attitudes towards timing of dialysis initiation in Canada.

BACKGROUND: Physicians' perceptions and opinions may influence when to initiate dialysis. OBJECTIVE: To examine providers' perspectives and opinions regarding the timing of dialysis initiation. DESIGN: Online survey. SETTING: Community and academic dialysis practices in Canada. PARTICIPANTS: A nationally-representative sample of dialysis providers. MEASUREMENTS AND METHODS: Dialysis providers opinions assessing reasons to initiate dialysis at low or high eGFR. Responses were obtained using a 9-point Likert scale. Early dialysis was defined as initiation of dialysis in an individual with an eGFR greater than or equal to 10.5 ml/min/m(2). A detailed survey was emailed to all members of the Canadian Society of Nephrology (CSN) in February 2013. The survey was designed and pre-tested to evaluate duration and ease of administration. RESULTS: One hundred and forty one (25% response rate) physicians participated in the survey. The majority were from urban, academic centres and practiced in regionally administered renal programs. Very few respondents had a formal policy regarding the timing of dialysis initiation or formally reviewed new dialysis starts (N = 4, 3.1%). The majority of respondents were either neutral or disagreed that late compared to early dialysis initiation improved outcomes (85-88%), had a negative impact on quality of life (89%), worsened AVF or PD use (84-90%), led to sicker patients (83%) or was cost effective (61%). Fifty-seven percent of respondents felt uremic symptoms occurred earlier in patients with advancing age or co-morbid illness. Half (51.8%) of the respondents felt there was an absolute eGFR at which they would initiate dialysis in an asymptomatic patient. The majority of respondents would initiate dialysis for classic indications for dialysis, such as volume overload (90.1%) and cachexia (83.7%) however a significant number chose other factors that may lead them to early dialysis initiation including avoiding an emergency (28.4%), patient preference (21.3%) and non-compliance (8.5%). LIMITATIONS: 25% response rate. CONCLUSIONS: Although the majority of nephrologists in Canada who responded followed evidence-based practice regarding the timing of dialysis initiation, knowledge gaps and areas of clinical uncertainty exist. The implementation and evaluation of formal policies and knowledge translation activities may limit potentially unnecessary early dialysis initiation.

CONTEXTE: Les perceptions et opinions des médecins peuvent influencer le moment d'initiation de la dialyse. OBJECTIF: Examiner les perspectives et opinions des médecins relatives au moment d'initiation de la dialyse. TYPE D'ÉTUDE: Sondage en ligne. ÉCHANTILLON: Unités de dialyse communautaires et académiques au Canada. PARTICIPANTS: Un échantillon représentatif de médecins au Canada. MÉTHODES ET INSTRUMENTS DE MESURE: Nous avons recueilli les opinions des professionnels impliqués en dialyse sur l'initiation de la dialyse basée sur le niveau de eDGF (inférieur ou supérieur à 10,5 mL/min/m2) grâce à un sondage envoyé à tous les membres de la Société canadienne de néphrologie en février 2013. Les réponses aux questions étaient exprimées par une échelle de Likert à 9 catégories. Nous avons préalablement testé le sondage afin d'évaluer sa durée et sa facilité d'administration. L'initiation précoce de la dialyse était définie par un début de dialyse en présence d'un eDGF supérieur ou égal à 10,5 mL/min/m2. RÉSULTATS: Cent quarante et un (taux de réponse de 25%) médecins ont participé au sondage. La majorité provenait de centres urbains et académiques et pratiquait dans des programmes régionaux de suppléance rénale. Très peu de répondants avaient un protocole formel pour le début de la dialyse ou avaient révisés les nouvelles initiations de dialyse (n = 4, 3,1%). La majorité des répondants était soit neutre ou en désaccord avec l'affirmation que l'initiation tardive, comparée à l'initiation précoce, améliore les issues (85-88%), réduit l'utilisation d'une FAV ou de la dialyse péritonéale (84-90%), conduit vers des patients plus malades (83%), ou était rentable (61%). Cinquante-sept pour cent des répondants estimaient que les symptômes urémiques apparaissent plus tôt chez les patients âgés ou souffrant de comorbidités. La moitié (51,8%) des répondants estimait qu'il existe un seuil de DFG où ils débuteraient la dialyse chez un patient asymptomatique. La majorité des répondants initierait la dialyse pour les indications classiques de dialyse, telles que la surcharge volémique (90,1%) et la cachexie (83,7%). Cependant, un nombre significatif de répondants ont rapporté d'autres facteurs qui les conduiraient à initier la dialyse précocement, incluant éviter une urgence (28,4%), la préférence du patient (21,3%) et l'inobservance (8,5%). LIMITES DE L'ÉTUDE: Taux de réponse de 25%. CONCLUSIONS: Bien que la majorité des néphrologues au Canada ait répondu selon les lignes directrices basées sur les données probantes pour le moment d'initiation de la dialyse, des lacunes de connaissance et des incertitudes cliniques existent. La mise en œuvre et l'évaluation de politiques formelles et d'activités de valorisation des connaissances pourraient limiter l'initiation de dialyse précoce non nécessaire.

The assessment, serial evaluation, and subsequent sequelae of acute kidney injury (ASSESS-AKI) study: design and methods.

BACKGROUND: The incidence of acute kidney injury (AKI) has been increasing over time and is associated with a high risk of short-term death. Previous studies on hospital-acquired AKI have important methodological limitations, especially their retrospective study designs and limited ability to control for potential confounding factors. METHODS: The Assessment, Serial Evaluation, and Subsequent Sequelae of Acute Kidney Injury (ASSESS-AKI) Study was established to examine how a hospitalized episode of AKI independently affects the risk of chronic kidney disease development and progression, cardiovascular events, death, and other important patient-centered outcomes. This prospective study will enroll a cohort of 1100 adult participants with a broad range of AKI and matched hospitalized participants without AKI at three Clinical Research Centers, as well as 100 children undergoing cardiac surgery at three Clinical Research Centers. Participants will be followed for up to four years, and will undergo serial evaluation during the index hospitalization, at three months post-hospitalization, and at annual clinic visits, with telephone interviews occurring during the intervening six-month intervals. Biospecimens will be collected at each visit, along with information on lifestyle behaviors, quality of life and functional status, cognitive function, receipt of therapies, interim renal and cardiovascular events, electrocardiography and urinalysis. CONCLUSIONS: ASSESS-AKI will characterize the short-term and long-term natural history of AKI, evaluate the incremental utility of novel blood and urine biomarkers to refine the diagnosis and prognosis of AKI, and identify a subset of high-risk patients who could be targeted for future clinical trials to improve outcomes after AKI.