Acute Kidney Injury in Hospitalized Patients with COVID-19

IMPORTANCE

Preliminary reports indicate that acute kidney injury (AKI) is common in coronavirus disease (COVID)-19 patients and is associated with worse outcomes. AKI in hospitalized COVID-19 patients in the United States is not well-described.

OBJECTIVE

To provide information about frequency, outcomes and recovery associated with AKI and dialysis in hospitalized COVID-19 patients.

DESIGN

Observational, retrospective study.

SETTING

Admitted to hospital between February 27 and April 15, 2020.

PARTICIPANTS

Patients aged ≥18 years with laboratory confirmed COVID-19 Exposures: AKI (peak serum creatinine increase of 0.3 mg/dL or 50% above baseline). Main Outcomes and Measures: Frequency of AKI and dialysis requirement, AKI recovery, and adjusted odds ratios (aOR) with mortality. We also trained and tested a machine learning model for predicting dialysis requirement with independent validation.

RESULTS

A total of 3,235 hospitalized patients were diagnosed with COVID-19. AKI occurred in 1406 (46%) patients overall and 280 (20%) with AKI required renal replacement therapy. The incidence of AKI (admission plus new cases) in patients admitted to the intensive care unit was 68% (553 of 815). In the entire cohort, the proportion with stages 1, 2, and 3 AKI were 35%, 20%, 45%, respectively. In those needing intensive care, the respective proportions were 20%, 17%, 63%, and 34% received acute renal replacement therapy. Independent predictors of severe AKI were chronic kidney disease, systolic blood pressure, and potassium at baseline. In-hospital mortality in patients with AKI was 41% overall and 52% in intensive care. The aOR for mortality associated with AKI was 9.6 (95% CI 7.4-12.3) overall and 20.9 (95% CI 11.7-37.3) in patients receiving intensive care. 56% of patients with AKI who were discharged alive recovered kidney function back to baseline. The area under the curve (AUC) for the machine learned predictive model using baseline features for dialysis requirement was 0.79 in a validation test.

CONCLUSIONS AND RELEVANCE

AKI is common in patients hospitalized with COVID-19, associated with worse mortality, and the majority of patients that survive do not recover kidney function. A machine-learned model using admission features had good performance for dialysis prediction and could be used for resource allocation.

The Role of Uric Acid in Acute Kidney Injury

Studies have demonstrated the presence of a strong association between serum uric acid (SUA) and acute kidney injury (AKI) consistently across several disease models. Exposure to SUA at different time periods and concentrations has reliably resulted in AKI whether assessed by conventional or novel biomarkers or by kinetic estimated glomerular filtration rate (KeGFR) engineered for non-steady dynamic states. In experimental models, moderate hyperuricemia was associated with an absence of intrarenal crystals, manifestation of tubular injury, macrophage infiltration, and increased expression of inflammatory mediators that were attenuated with uric acid lowering therapy with rasburicase, a recombinant urate oxidase. In a pilot clinical trial, treatment with rasburicase was associated with a decreased incidence of AKI and evidence for less renal structural injury. Lowering SUA also improved KeGFR and estimated glomerular filtration rate in 2 separate studies. SUA has also been linked to diabetic nephropathy, hypertension, cardiovascular disease, chronic kidney disease, metabolic syndrome, and their mechanisms of action share many common traits. In this article, we explore the evidence for the causal role of SUA in AKI using Bradford Hill criteria as a guideline with data integration from related fields.

Utilization of parathyroidectomy for secondary hyperparathyroidism in end-stage renal disease

Background

The utilization of parathyroidectomy (PTX) to manage secondary hyperparathyroidism (SHPT) refractory to medical management (MTX) in end-stage renal disease (ESRD) in the era of calcimimetics is not well known.

Methods

Adult ESRD patients receiving dialysis between August 2007 and December 2011 at our institution with an intact parathyroid hormone (iPTH) level ≥88 pmol/L for 6 months associated with hypercalcemia and/or hyperphosphatemia for at least 50% of that period were included. Baseline characteristics and iPTH, calcium, phosphorus, calcium–phosphorus product and alkaline phosphatase (ALP) at baseline, 6 and 12 months were compared between the two groups (PTX versus MTX) using the χ² and paired t-tests.

Results

Of the total population of 687 patients, 80 (11.6%) satisfied KDOQI criteria for PTX, most of whom did not receive PTX (81.2%). At baseline, PTX patients had been on dialysis longer (P = 0.001), with higher iPTH (P < 0.001), calcium (P = 0.008) and ALP (P = 0.001) and were less likely to be African-American (P = 0.007). Complete follow-up data at 6 months were available on 75 patients (PTX = 15; MTX = 60). PTX had significantly greater reduction in iPTH (93 versus 23%) and ALP (68 versus 0%) compared with MTX. Changes from baseline in calcium, phosphate or calcium–phosphorus product levels and proportion of patients achieving KDOQI target values were not significant for either intervention. Findings were consistent at 12 months.

Conclusions

A significant proportion of ESRD patients who met indications for PTX did not receive it. Additional studies are needed to understand the barriers that prevent patients from receiving PTX, thereby resulting in underutilization.

Where should electronic records for patients be stored?

INTRODUCTION

The importance of a nationwide health information infrastructure (NHII) is widely recognized. Patient data may be stored where it happens to be created (the distributed or institution-centric model) or in one place for a given patient (the centralized or patient-centric model). Minimal data is available regarding the performance implications of these alternative architectural choices.

OBJECTIVE

To help identify the architecture best suited for efficient and complete nationwide health information exchange based on the large-scale operational characteristics of these architectures.

DESIGN

We used simulation to study the impact of health care record (data) fragmentation and probability of encounter on transaction volume and data retrieval failure rate as markers of performance for each of the above architectures.

RESULTS

Data fragmentation and the probability of encounter directly correlate with transaction volume and are significantly higher for the distributed model when the number of data nodes >4 (p<0.0001). The number of data retrieval failures increases in proportion to fragmentation and is significantly higher for the distributed model when the number of data nodes ≥2 (p<0.0059).

CONCLUSION

In simulation studies, the distributed model scaled poorly in terms of data availability and integrity with a higher failure rate when compared to the centralized model of data storage. Choice of architecture may have implications on the efficiency, usability, and effectiveness of the NHII at the point of care.

Elevated uric acid increases the risk for acute kidney injury

BACKGROUND

Uric acid has been proposed to play a role in acute kidney injury. We therefore investigated the potential influence of preoperative serum uric acid (SUA) on acute kidney injury in patients undergoing cardiovascular (CV) surgery. The primary aims were to investigate the incidence of acute kidney injury, peak serum creatinine (SCr) concentrations, hospital length of stay, and days on mechanical ventilation.

METHODS

Retrospective study included patients who underwent CV surgery and had preoperative SUA available. Acute kidney injury was defined as an absolute increase in SCr ≥0.3 mg/dL from baseline within 48 hours after surgery. Univariate and multivariate logistic regression analysis was performed to determine the odds ratio for acute kidney injury.

RESULTS

There were 190 patients included for analysis. SUA were divided into deciles. The incidences of acute kidney injury were higher with higher deciles of SUA. When the incidences of acute kidney injury were plotted against all available values of SUA at increments of 0.5 mg/dL, a J-shaped curve emerged demonstrating higher incidences of acute kidney injury associated with both hypo- and hyperuricemia. In the univariate analysis, SUA ≥5.5 mg/dL was associated with a 4-fold (odds ratio [OR] 4.4; 95% confidence interval [CI], 2.4-8.2), SUA ≥6 mg/dL with a 6-fold (OR 5.9; 95% CI, 3.2-11.3), SUA ≥6.5 mg/dL with an 8-fold (OR 7.9; 95% CI, 3.9-15.8), and SUA ≥7 mg/dL with a 40-fold (OR 39.1; 95% CI, 11.6-131.8) increased risk for acute kidney injury. In the multivariate analysis, SUA ≥7 mg/dL also was associated with a 35-fold (OR 35.4; 95% CI, 9.7-128.7) increased risk for acute kidney injury. The 48-hour postoperative and hospital-stay mean peak SCr levels also were higher in the SUA ≥5.5 mg/dL group compared with the SUA <5 mg/dL group. SUA ≥7 mg/dL was associated with increased length of hospital stay (SUA <7 mg/dL, 18.5 ± 1.8 days vs SUA ≥7 mg/dL, 32.0 ± 6.8 days, P = 0.058) and a longer duration of mechanical ventilation support (SUA <7 mg/dL, 2.4 ± 0.4 days vs SUA ≥7 mg/dL, 20.4 ± 4.5 days, P = 0.001).

CONCLUSION

Preoperative SUA was associated with increased incidence and risk for acute kidney injury, higher postoperative SCr values, and longer hospital length of stay and duration of mechanical ventilation support in patients undergoing cardiac surgery. A J-shaped relationship appears to exist between SUA and acute kidney injury.

Critically ill obstetric patients in an American and an Indian public hospital: comparison of case-mix, organ dysfunction, intensive care requirements, and outcomes

OBJECTIVE

To compare case-mix, health care practices, and outcome in obstetric ICU admissions in inner-city teaching hospitals in economically developed and developing countries.

DESIGN

Retrospective study.

SETTING

Ben Taub General Hospital (BTGH), Houston, Texas, and King Edward Memorial Hospital (KEMH), Mumbai, India.

PATIENTS

Women admitted during pregnancy or 6 weeks postpartum between 1992 and 2001.

MEASUREMENTS AND RESULTS

Patients from BTGH (n=174) and KEMH (n=754) had comparable age, number of organs affected, incidence of medical disorders (30%), liver dysfunction, and thrombocytopenia. Fewer KEMH patients received prenatal care (27 vs 86%) and came to hospital within 24 h of onset of symptoms (60 vs 90%). They had higher APACHE II scores (median 16 vs 10), greater incidence of neurological (63 vs 36%), renal (50 vs 37%), and cardiovascular dysfunction (39 vs 29%). Severe malaria, viral hepatitis, cerebral venous thrombosis, and poisoning were common medical disorders. The BTGH group had higher incidence of respiratory dysfunction (59 vs 46%) and disseminated intravascular coagulation (40 vs 23%), placental anomalies, HELLP syndrome, chorioamnionitis, peripartum cardiomyopathy, puerperal sepsis, urinary infection, bacteremia, substance abuse, and asthma. More BTGH patients required mechanical ventilation and blood component therapy, whereas more KEMH patients needed dialysis. Of BTGH patients, 78.2% were delivered by cesarean section (vs 15.4%). Maternal (2.3 vs 25%) and fetal (13 vs 51%) mortality were lower in BTGH patients.

CONCLUSIONS

There were marked differences in medical diseases, organ failure, and intensive care needs. Higher mortality in the Indian ICU may be due to difference in case mix, inadequate prenatal care, delay in reaching hospital, and greater severity of illness.

Prognostic factors in obstetric patients admitted to an Indian intensive care unit

OBJECTIVES

Obstetric patients form a significant proportion of intensive care unit admissions in countries like India, where maternal mortality is high (440 per 100,000 deliveries). We studied the diseases requiring intensive care and prognostic factors in obstetric patients.

DESIGN

Retrospective chart review. Acute Physiology and Chronic Health Evaluation (APACHE) II data were prospectively collected.

SETTING

Multidisciplinary intensive care unit of a public hospital in Mumbai, India.

PATIENTS

Women admitted during pregnancy or 6 wks post-partum during a 5-yr study period (1997-2001).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Four hundred fifty-three obstetric patients (age 25.5 +/- 4.6 yrs [mean +/- SD], mean gestational age 31 wks) were admitted (548 intensive care unit admissions per 100,000 deliveries), 138 with single organ failure and 152 with multiple organ failure. Ninety-eight women died (mortality rate 21.6%). Mortality was comparable in antepartum (n = 216) and postpartum (n = 247) admissions but increased with increasing number of organs affected. There were 236 fetal deaths (52%), of which 104 occurred before hospital admission. Median APACHE II score was 16 (interquartile range, 10-24), and standardized mortality ratio (observed deaths/predicted deaths) was 0.78. Compared with pregnant patients admitted with obstetric disorders (n = 313), those with medical diseases (n = 140) had significantly lower APACHE II scores (median 14 vs. 17) but higher observed mortality rate (28.6% vs. 18.5%; odds ratio, 1.76; 95% confidence interval, 1.08-2.87) and standardized mortality ratio (1.09 vs. 0.66). On multivariate analysis, increased mortality rate was associated with acute cardiovascular (odds ratio, 5.8), nervous system (odds ratio, 4.73) and respiratory (odds ratio, 12.9) failure, disseminated intravascular coagulation (odds ratio, 2.4), viral hepatitis (odds ratio, 5.8), intracranial hemorrhage (odds ratio, 5.4), absence of prenatal care (odds ratio, 1.94), and >24 hrs interval between onset of acute symptoms and intensive care unit admission (odds ratio, 2.3).

CONCLUSIONS

Multiple organ failure is common in obstetric patients; mortality rate increases with increasing organ failure. APACHE II scores overpredict mortality rate. Standardized mortality ratio is lower in obstetric disorders than in medical disorders. Lack of prenatal care and delay in intensive care unit referral adversely affect outcome and are easily preventable.