Extreme Humid-Heat Exposure and Mortality Among Patients Receiving Dialysis.

RATIONALE & OBJECTIVE: Exposure to extreme heat events has been linked to increased morbidity and mortality in the general population. Patients receiving maintenance dialysis may be vulnerable to greater risks from these events, but this is not well understood. We characterized the association of extreme heat events and the risk of death among patients receiving dialysis in the United States. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: Data from the US Renal Data System were used to identify adults living in US urban settlements prone to extreme heat who initiated maintenance dialysis between 1997 and 2016. EXPOSURE: An extreme heat event, defined as a time-updated heat index (a humid-heat metric) exceeding 40.6°C for≥2 days or 46.1°C for≥1day. OUTCOME: Death. ANALYTICAL APPROACH: Cox proportional hazards regression to estimate the elevation in risk of death during a humid-heat event adjusted for age, sex, year of dialysis initiation, dialysis modality, poverty level, and climate region. Interactions between humid-heat and these same factors were explored. RESULTS: Among 945,251 adults in 245 urban settlements, the mean age was 63 years, and 44% were female. During a median follow-up period of 3.6 years, 498,049 adults were exposed to at least 1 of 7,154 extreme humid-heat events, and 500,025 deaths occurred. In adjusted models, there was an increased risk of death (hazard ratio 1.18 [95% CI, 1.15-1.20]) during extreme humid-heat exposure. The relative mortality risk was higher among patients living in the Southeast (P<0.001) compared with the Southwest. LIMITATIONS: Possibility of exposure misclassification, did not account for land use and air pollution co-exposures. CONCLUSIONS: This study suggests that patients receiving dialysis face an increased risk of death during extreme humid-heat exposure. PLAIN-LANGUAGE SUMMARY: Patients who receive dialysis are vulnerable to extreme weather events, and rising global temperatures may bring more frequent extreme heat events. We sought to determine whether extreme heat exposure was associated with an increased risk of death in urban-dwelling patients receiving dialysis across the United States. We found that people receiving dialysis were more likely to die during extreme humid-heat events, defined by a heat index exceeding 40.6°C (105°F) for≥2 days or 46.1°C (115°F) for≥1day. These findings inform the nephrology community about the potential importance of protecting patients receiving maintenance dialysis from the risks associated with extreme heat.

Dihydropyridine Calcium Channel Blockers and Kidney Outcomes.

BACKGROUND: Early trials of dihydropyridine calcium channel blockers (DCCBs) suggest a detrimental effect on intraglomerular pressure and an association with albuminuria. OBJECTIVE: We sought to evaluate the associations of DCCB initiation with albuminuria and kidney failure with replacement therapy (KFRT) and to determine whether renin-angiotensin system (RAS) blockade modified these associations. DESIGN: We conducted a target trial emulation study using a new user, active comparator design and electronic health record data from Geisinger Health. PARTICIPANTS: We included patients without severe albuminuria or KFRT who were initiated on a DCCB or thiazide (active comparator) between January 1, 2004, and December 31, 2019. MAIN MEASURES: Using inverse probability of treatment weighting, we performed doubly robust Cox proportional hazards regression to estimate the association of DCCB initiation with incident severe albuminuria (urine albumin to creatinine ratio > 300 mg/g) and KFRT, overall and stratified by RAS blocker use. KEY RESULTS: There were 11,747 and 26,758 eligible patients initiating a DCCB and thiazide, respectively, with a weighted baseline mean age of 60 years, systolic blood pressure of 143 mm Hg, and eGFR of 86 mL/min/1.73 m2, and with a mean follow-up of 8 years. Compared with thiazides, DCCBs were significantly associated with the development of severe albuminuria (hazard ratio [HR], 1.29; 95% confidence interval [CI], 1.16-1.43), with attenuation of risk in the presence of RAS blockade (P for interaction < 0.001). The risk of KFRT was increased among patients without RAS blockade (HR, 1.66; 95% CI, 1.19-2.31), but not with RAS blockade (P for interaction = 0.005). CONCLUSIONS: DCCBs were associated with increased risk of albuminuria and, in the absence of RAS blockade, KFRT. These findings suggest coupling DCCB therapy with RAS blockade may mitigate adverse kidney outcomes.

Hurricanes and Mortality among Patients Receiving Dialysis.

BACKGROUND: Hurricanes are severe weather events that can disrupt power, water, and transportation systems. These disruptions may be deadly for patients requiring maintenance dialysis. We hypothesized that the mortality risk among patients requiring maintenance dialysis would be increased in the 30 days after a hurricane. METHODS: Patients registered as requiring maintenance dialysis in the United States Renal Data System who initiated treatment between January 1, 1997 and December 31, 2017 in one of 108 hurricane-afflicted counties were followed from dialysis initiation until transplantation, dialysis discontinuation, a move to a nonafflicted county, or death. Hurricane exposure was determined as a tropical cyclone event with peak local wind speeds ≥64 knots in the county of a patient's residence. The risk of death after the hurricane was estimated using time-varying Cox proportional hazards models. RESULTS: The median age of the 187,388 patients was 65 years (IQR, 53-75) and 43.7% were female. There were 27 hurricanes and 105,398 deaths in 529,339 person-years of follow-up on dialysis. In total, 29,849 patients were exposed to at least one hurricane. Hurricane exposure was associated with a significantly higher mortality after adjusting for demographic and socioeconomic covariates (hazard ratio, 1.13; 95% confidence interval, 1.05 to 1.22). The association persisted when adjusting for seasonality. CONCLUSIONS: Patients requiring maintenance dialysis have a higher mortality risk in the 30 days after a hurricane.

Blood pressure parameters are associated with all-cause and cause-specific mortality in chronic kidney disease.

Previous observational studies reported J or U-shaped associations between blood pressure parameters and mortality in patients with chronic kidney disease (CKD). Here we examined the associations of different blood pressure levels with various causes of death in a CKD population that included patients with eGFR 15-59 ml/min/1.73 m2 with underlying hypertension receiving at least one antihypertensive agent. We obtained data on date and cause of death from State Department of Health mortality files and classified deaths into three categories: cardiovascular, malignancy-related, and non-cardiovascular/non-malignancy related. Cox models were fitted for overall mortality, and separate competing risk regression models for each major cause of death category, to evaluate their associations with various systolic and diastolic blood pressures. During a median follow-up of 3.9 years, 13,332 of 45,412 patients died. Systolic blood pressures under 100, 100-109, 110-119, and over 150 (vs. 130-139 mm Hg) were associated with higher all-cause and cardiovascular mortality. Systolic blood pressures under 100 mm Hg and 100-109 were associated with higher non-cardiovascular/non-malignancy related mortality. Diastolic blood pressures under 50 and 50-59 (vs. 70-79 mm Hg) were associated with higher all-cause and non-cardiovascular/non-malignancy-related mortality while diastolic blood pressures over 90 mm Hg was associated with higher cardiovascular but lower non-cardiovascular/non-malignancy related mortality. Thus, in a non-dialysis dependent CKD population, systolic blood pressures under 110 and over 150 mm Hg were associated with cardiovascular and non-cardiovascular/non-malignancy related deaths. However, diastolic blood pressure under 60 mm Hg was associated in contrast with all-cause mortality and non-cardiovascular/non-malignancy-related deaths.

Comparison of normothermic and hypothermic perfusion in porcine kidneys donated after cardiac death.

BACKGROUND: Normothermic machine perfusion (NMP) is an alternative strategy for preserving kidneys donated after cardiac death (DCD). The relative efficacy of prolonged NMP compared to hypothermic machine perfusion (HMP) in DCD kidneys with moderate ischemic injury is undetermined. This study compares NMP and HMP kidney preservation in a porcine DCD model. METHODS: Ten porcine kidneys underwent NMP or HMP preservation following 45 minutes of warm ischemia and 5 hours of cold ischemia. After 8 hours of machine preservation, hemodynamic stability, renal function, perfusate biomarkers, and histologic integrity were assessed in a simulated reperfusion model. RESULTS: During simulated reperfusion, no differences were observed in oxygen consumption, urine production, creatinine clearance, fractional excretion of sodium, proteinuria, and perfusate levels of lactate dehydrogenase and aspartate aminotransferase. Resistance was no different after 30 minutes of simulated reperfusion. Histologically, NMP kidneys demonstrated increased vacuolization after preservation and greater loss of tubular integrity after simulated reperfusion. Perfusate levels of alkaline phosphatase (AP) and gamma glutamyltransferase (GGT) were higher in NMP kidneys during preservation, but upon simulated reperfusion, AP and GGT levels were higher in HMP-preserved kidneys. Peak AP and GGT during simulated reperfusion of HMP kidneys were over 14 times higher than peak AP and GGT during preservation of NMP kidneys. CONCLUSIONS: NMP provided comparable preservation of renal function as HMP and minimized AP and GGT release upon reperfusion.

Trousseau's Syndrome in Cholangiocarcinoma: The Risk of Making the Diagnosis.

We report a case of Trousseau's syndrome with cholangiocarcinoma complicated by a fatal pulmonary embolism after liver biopsy. A 69-year-old man who presented with right upper quadrant pain was found to have portal vein thrombosis and nonspecific liver hypodensities after imaging by computerized tomography. Following four days of anticoagulation, heparin was held for percutaneous liver biopsy. After the biopsy, he developed acute hepatic failure, acute kidney injury, lactic acidemia, and expired. Autopsy revealed intrahepatic cholangiocarcinoma and a pulmonary embolism. Trousseau's syndrome with cholangiocarcinoma is rarely reported and has a poor prognosis. This case highlights a fundamental challenge in the diagnosis and early management of intrahepatic cholangiocarcinoma with hypercoagulability. Diagnostic biopsy creates an imperative to reduce post-operative bleeding risk, but this conflicts with the need to reduce thrombotic risk in a hypercoagulable state. Considering the risk of withholding anticoagulation in patients with proven or suspected cholangiocarcinoma complicated by portal vein thrombosis, physicians should consider biopsy procedures with lesser bleeding risks, such as transjugular liver biopsy or plugged percutaneous liver biopsy, to minimize interruption of anticoagulation.

Renin: Measurements, Correlates, and Associations With Long-Term Adverse Kidney Outcomes.

BACKGROUND: The association of renin with adverse kidney outcomes is largely unknown, and renin measurement strategies vary. We aimed to measure the clinical correlates of different renin measurements and the association between renin and incident chronic kidney disease (CKD), end-stage kidney disease (ESKD), and mortality. METHODS: We performed a prospective cohort analysis of 9,420 participants in the Atherosclerosis Risk in Communities study followed from 1996 to 1998 through 2019. We estimated longitudinal associations of renin measured using SomaScan modified nucleotide aptamer assay with incident CKD, ESKD, and death using Cox proportional hazards models. Using samples from a subsequent study visit, we compared SomaScan renin with plasma renin activity (PRA) and renin level from Olink, and estimated associations with covariates using univariate and multivariable regression. RESULTS: Higher SomaScan renin levels were associated with a higher risk of incident CKD (hazard ratio per two-fold higher [HR], 1.14; 95% confidence interval [CI], 1.09 to 1.20), ESKD (HR, 1.20; 95% CI, 1.03 to 1.41), and mortality (HR, 1.08; 95% CI, 1.04 to 1.13) in analyses adjusted for demographic, clinical, and socioeconomic covariates. SomaScan renin was moderately correlated with PRA (r = 0.61) and highly correlated with Olink renin (r = 0.94). SomaScan renin and PRA had similar clinical correlates except for divergent associations with age and beta-blocker use, both of which correlated positively with SomaScan renin but negatively with PRA. CONCLUSIONS: SomaScan aptamer-based renin level was associated with a higher risk of CKD, ESKD, and mortality. It was moderately correlated with PRA, sharing generally similar clinical covariate associations.

Particulate Matter and Albuminuria, Glomerular Filtration Rate, and Incident CKD.

BACKGROUND AND OBJECTIVES: Exposure to particulate matter (PM) <2.5 µm in aerodynamic diameter (PM2.5) has been linked to detrimental health effects. This study aimed to describe the relationship between long-term PM2.5 exposure and kidney disease, including eGFR, level of albuminuria, and incident CKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: The study included 10,997 participants from the Atherosclerosis Risk in Communities cohort who were followed from 1996-1998 through 2016. Monthly mean PM2.5 concentrations (µg/m3) were estimated at geocoded participant addresses using geographic information system-based, spatiotemporal generalized additive mixed models-including geospatial covariates such as land use-and then averaged over the 12-month period preceding participant examination. Covariate-adjusted, cross-sectional associations of PM2.5, baseline eGFR, and urinary albumin-creatinine ratio (UACR) were estimated using linear regression. PM2.5 and incident CKD (defined as follow-up eGFR <60 ml/min per 1.73 m2 with ≥25% eGFR decline relative to baseline, CKD-related hospitalization or death based on International Classification of Diseases 9/10 codes, or development of ESKD) associations were estimated using Cox proportional hazards regression. Modeling was stratified by study site, and stratum-specific estimates were combined using random-effects meta-analyses. RESULTS: Baseline mean participant age was 63 (±6) years and eGFR was 86 (±16) ml/min per 1.73 m2. There was no significant PM2.5-eGFR association at baseline. Each 1-µg/m3 higher annual average PM2.5 was associated with higher UACR after adjusting for demographics, socioeconomic status, and clinical covariates (percentage difference, 6.6%; 95% confidence interval [95% CI], 2.6% to 10.7%). Each 1-µg/m3 higher annual average PM2.5 was associated with a significantly higher risk of incident CKD (hazard ratio, 1.05; 95% CI, 1.01 to 1.10). CONCLUSIONS: Exposure to higher annual average PM2.5 concentrations was associated with a higher level of albuminuria and higher risk for incident CKD in a community-based cohort.

Development of a prolonged warm ex vivo perfusion model for kidneys donated after cardiac death.

PURPOSE: Ex vivo perfusion of marginal kidney grafts offers the chance to expand the donor pool, but there is no current clinical standard for the prolonged warm perfusion of renal grafts. This exploratory pilot study seeks to identify a stable ex vivo kidney perfusion model that can support low intravascular resistance and preserve histologic architecture in a porcine donation after cardiac death (DCD) model. METHODS: 15 kidneys were preserved in 1 of 3 settings: normothermic whole blood (NT-WB), normothermic Steen Solution™ (XVIVO Perfusion) with whole blood (NT-Steen/WB), or subnormothermic Steen Solution™ at 21°C (SNT-Steen). Kidneys were primarily assessed using hemodynamic parameters and histologic analysis. RESULTS: NT-WB perfusion resulted in high vascular resistance and glomerular necrosis. NT-Steen/WB and SNT-Steen resistance ranged between 0.18-0.45 mmHg/mL per minute and 0.25-0.53 mmHg/mL per minute, respectively, enabling stable perfusion for up to 24 hours. NT-Steen/WB demonstrated tubular and glomerular necrosis, while the histologic architecture of SNT-Steen was preserved with the exception of numerous proteinaceous casts. CONCLUSIONS: Our results suggest that ex vivo kidney perfusion with Steen Solution™ at 21°C supports low and stable vascular resistance and provides adequate histologic preservation during 24-hour perfusion.