Psoas Muscle Index as a Predictor of Perioperative Outcomes in Geriatric Patients Undergoing Spine Surgery

Study Design Single-center retrospective study. Objective The objective of this study was to evaluate the association of psoas muscle mass defined sarcopenia with perioperative outcomes in geriatric patients undergoing elective spine surgery. Methods We included geriatric patients undergoing thoracolumbar spinal surgery. Total psoas surface area (TPA) was measured on preoperative axial computerized tomography or magnetic resonance imaging at the L3 vertebra and normalized to the L3 vertebral body area. Patients were divided into quartiles by normalized TPA, and the fourth quartile (Q4) was compared to quartiles 1–3 (Q1-3). Outcomes included perioperative transfusions, length of stay (LOS), delirium, pseudoarthrosis, readmission, discharge disposition, revision surgery, and mortality. Results Of the patients who met inclusion criteria (n = 196), the average age was 73.4 y, with 48 patients in Q4 and 148 patients in Q1-3. Q4 normalized TPA cut-off was <1.05. Differences in Q4 preoperative characteristics included significantly lower body mass index, baseline creatinine, and a greater proportion of females (Table 1). Q4 patients received significantly more postoperative red blood cell and platelet transfusions and had longer ICU LOS ( P < .05; Table 2). There was no difference in intraoperative transfusion volumes, delirium, initiation of walking, discharge disposition, readmission, pseudoarthrosis, or revision surgery (Tables 2 and 3). Mortality during follow-up was higher in Q4 but was not statistically significant ( P = .075). Conclusion Preoperative TPA in geriatric patients undergoing elective spine surgery is associated with increased need for intensive care and postoperative blood transfusion. Preoperative normalized TPA is a convenient measurement and could be included in geriatric preoperative risk assessment algorithms.

AKI in Hospitalized Children: Poorly Documented (and Underrecognized)

Background: Acute kidney injury (AKI) is common in hospitalized children. We hypothesized that hospital-acquired AKI would be underrecognized and under-reported, with potential implications for prevention of future AKI and CKD risk stratification.Methods: Five hundred thirty-two cases of AKI occurring over a 1 year period in a tertiary children's hospital in the United States were studied. AKI documentation was defined as any mention of AKI in the admission history and physical note, progress notes, or discharge summary. Nephrology follow-up was defined as a completed outpatient clinic visit within 1 year of discharge. Logistic regression was used to assess factors associated with documentation, consultation, and follow-up.Results: AKI developed during 584/7,640 (7.6%) of hospitalizations: 532 cases met inclusion criteria. Documentation was present in 34% (185/532) of AKI cases and 90 (16.9%) had an inpatient nephrology consult. Among 501 survivors, 89 (17.8%) had AKI in their hospital discharge summary and 54 had outpatient nephrology follow up. Stage 3 AKI, peak creatinine &gt;1 mg/dL and longer length of stay were associated with documentation. Stage 3 AKI and higher baseline creatinine were associated with inpatient nephrology consultation. Inpatient nephrology consultation was positively associated with outpatient nephrology follow up, but documentation in the discharge summary was not.Conclusion: Most cases of AKI were not documented and the proportion of children seen by a nephrologist was low, even among those with more severe injury. Increased severity of AKI was associated with documentation and inpatient consultation. Poor rates of documentation has implications for AKI recognition and appropriate management and follow up.

Defining Baseline Creatinine for Identification of Acute Kidney Injury in Population-based Laboratory Databases - A Danish Nationwide Cohort Study

Background: The baseline creatinine level is central in the KDIGO criteria of acute kidney injury (AKI), but baseline creatinine is often inconsistently defined or unavailable in AKI research. We examined the rate, characteristics, and 30-day mortality of AKI in five AKI cohorts created using different definitions of baseline creatinine. Methods: This nationwide cohort study included all individuals aged ≥18 in Denmark with a creatinine measurement in year 2017. Applying the KDIGO criteria, we created four AKI cohorts using four different baseline definitions (most recent, mean, or median value of outpatient creatinine 365-8 days before, or median value 90-8 days before if available otherwise median value 365-91 days before) and one AKI cohort not using a baseline value. AKI rate and the distribution of age, sex, baseline creatinine, and comorbidity was described for each AKI cohort, and the 30-day all-cause mortality was estimated using the Kaplan-Meier method. Results: The study included 2,095,850 adults with at least one creatinine measurement in 2017. The four different baseline definitions identified between 61,189 and 62,597 AKI episodes. The AKI rate in these four cohorts was 13-14 per 1,000 person-years, and 30-day all-cause mortality was 17-18%. The cohort created without using a baseline creatinine included 37,659 AKI episodes, corresponding to an AKI rate of 8.2 per 1,000 person-years, and a 30-day mortality of 23%. All five cohorts were similar regarding age, sex, and comorbidity. Conclusions: In a population-based setting with available outpatient baseline creatinine, different baseline creatinine definitions revealed comparable AKI cohorts, while the lack of a baseline creatinine when defining AKI led to a smaller AKI cohort with a higher mortality. These findings underscore the importance of availability and consistent use of an outpatient baseline creatinine, in particular in studies of community-acquired AKI.

Age and baseline creatinine as risk factors for methotrexate nephrotoxicity in children with acute lymphoblastic leukemia in resource-limited countries

Introduction. The search for risk factors for high-dose methotrexate (MTX)–induced nephrotoxicity in children with acute lymphoblastic leukemia (ALL) has been complex in the context of resource-limited countries where serum levels of MTX are not always available. Objective. To analyze the demographic, clinical, and biochemical factors associated with MTX-induced nephrotoxicity in children with ALL. Methodology. Case-control study in children with ALL from a General Hospital in Mexico over a four-year period (2016-2020). Kidney damage was defined with KDIGO criteria and the following variables were analyzed: sex, age, weight, height, creatinine, urea, transaminases, hematic cytometry, vomiting, mucositis, dermatitis, and number of MTX applications. Results: One hundred and eight children were studied, 22 females (38%) and 36 males (62%), ages 1 to14 years. The incidence of nephrotoxicity was 5.8% in 238 events of MTX administration. The children in the group with nephrotoxicity were older (average age 9.5 vs 5, p = 0.036), had higher baseline creatinine (0.5 mg/dL vs 0.4 mg/dL p = 0.006), and had lower baseline hemoglobin (10.1 g/dL vs 11.3 g/dL, p = 0.034). Mucositis was associated with nephrotoxicity with OR 13 95% CI 4-42, p <0.001. A cut-off value for creatinine of 0.44 mg/dL (AUC of 68%) and an age of 8 years (AUC of 64%) were identified for risk of nephrotoxicity. Conclusions: The incidence of MTX nephrotoxicity in children with ALL was 5.8%, with a high association with mucositis. The risk is greater for children older than 8 years and baseline creatinine higher than 0.44 mg/dL.

Estimation of Baseline Serum Creatinine with Machine Learning

<b><i>Introduction:</i></b> Comparing current to baseline serum creatinine is important in detecting acute kidney injury. In this study, we report a regression-based machine learning model to predict baseline serum creatinine. <b><i>Methods:</i></b> We developed and internally validated a gradient boosting model on patients admitted in Mayo Clinic intensive care units from 2005 to 2017 to predict baseline creatinine. The model was externally validated on the Medical Information Mart for Intensive Care III (MIMIC III) cohort in all ICU admissions from 2001 to 2012. The predicted baseline creatinine from the model was compared with measured serum creatinine levels. We compared the performance of our model with that of the backcalculated estimated serum creatinine from the Modification of Diet in Renal Disease (MDRD) equation. <b><i>Results:</i></b> Following ascertainment of eligibility criteria, 44,370 patients from the Mayo Clinic and 6,112 individuals from the MIMIC III cohort were enrolled. Our model used 6 features from the Mayo Clinic and MIMIC III datasets, including the presence of chronic kidney disease, weight, height, and age. Our model had significantly lower error than the MDRD backcalculation (mean absolute error [MAE] of 0.248 vs. 0.374 in the Mayo Clinic test data; MAE of 0.387 vs. 0.465 in the MIMIC III cohort) and higher correlation (intraclass correlation coefficient [ICC] of 0.559 vs. 0.050 in the Mayo Clinic test data; ICC of 0.357 vs. 0.030 in the MIMIC III cohort). <b><i>Discussion/Conclusion:</i></b> Using machine learning models, baseline serum creatinine could be estimated with higher accuracy than the backcalculated estimated serum creatinine level.

A Rare Case of Patiromer Induced Hypercalcemia

Patiromer is a calcium (Ca)-potassium (K) exchange resin approved for the treatment of hyperkalemia. Disorders of Ca or acid base balance were not reported in pre-approval clinical trials. We present a case of a patient with chronic kidney disease (CKD) with an unusual picture of hypercalcemia, metabolic alkalosis and hypokalemia upon intensification of patiromer dosing. A 56-year-old white man with CKD stage 4 (baseline creatinine 2.8 mg/dL) due to type 1 diabetes mellitus, proteinuria (1.5 g/g) and persistently high serum potassium 5.9 mEq/L attributed to type 4 renal tubular acidosis was evaluated in clinic. Due to high risk of CKD progression, patiromer 8.4 g daily, followed by 16.8 g daily was prescribed to enable renin angiotensin aldosterone system (RAAS) inhibitor. After 5 months of being on patiromer 16.8 g daily, routine laboratory tests revealed serum potassium 2.5 mEq/L, serum calcium 12.8 mg/dL and carbon dioxide 34 mEq/L. Patiromer was discontinued and thorough investigation held was negative for other causes of hypercalcemia. Five days after patiromer discontinuation, serum calcium returned to normal. The role of secondary hyperparathyroidism in this case remains unclear. We, therefore recommend cautious vigilance of patients receiving patiromer and undergoing dose escalation.

Comparison of Static and Dynamic Baseline Creatinine Surrogates for Defining Acute Kidney Injury

<b><i>Background:</i></b> “Dynamic” baseline serum creatinine (sCr), based on a rolling 48-h window, and a static baseline sCr (previous outpatient sCr) were used to define acute kidney injury (AKI). <b><i>Methods:</i></b> Retrospective cohort study of adult admissions to the University of Alabama (UAB) Health System hospitals for years 2016–2018. Included admissions had &#x3e;1- and &#x3c;180-day length of stay, &#x3e;2 inpatient sCr measurements, and an averaged estimated glomerular filtration rate &#x3e;15 mL/min/1.73 m². The final cohort of 62,380 patients included 100,570 admissions, 3,509 inpatient deaths, and 1,916 admissions with inpatient dialysis. AKI was defined by Kidney Disease Improving Global Outcomes (KDIGO) criteria and a static or dynamic baseline sCr. Discrimination was evaluated with area under receiver operator curves (AUC), logistic regression, and net reclassification improvement (NRI). <b><i>Results:</i></b> Preadmission outpatient “static” sCr values were available for 43,433 admissions. The lowest sCr value during a rolling 48-h window before each inpatient sCr defined a “dynamic” baseline sCr. Using point-wise comparisons, the dynamic baseline sCr performed better than static baseline sCr for inpatient mortality (AUC [0.819 vs. 0.741; <i>p</i> &#x3c; 0.001] and NRI ≥0.306 [<i>p</i> &#x3c; 0.001]) and inpatient dialysis (AUC [0.903 vs. 0.864; <i>p</i> &#x3c; 0.001] and NRI ≥0.317 [<i>p</i> &#x3c; 0.001]). <b><i>Conclusions:</i></b> The dynamic baseline sCr is available without reference to preadmission sCr values and avoids confounding associated with missing outpatient sCr values. AKI defined with the dynamic baseline sCr significantly improved discrimination of risk for inpatient mortality and dialysis compared to static baseline sCr.

Association of the classification and severity of heart failure with the incidence of contrast-induced acute kidney injury

Congestive heart failure (HF) is a known risk factor of contrast-induced acute kidney injury (CI-AKI). However, the relationship of the classification and severity of HF with CI-AKI remains under-explored. From January 2009 to April 2019, we recruited patients undergoing elective PCI who had complete pre- and post-operative creatinine data. According to the levels of ejection fraction (EF), HF was classified as HF with reduced EF (HFrEF) [EF < 40%], HF with mid-range EF (HFmrEF) [EF 40–49%] and HF with preserved EF (HFpEF) [EF ≥ 50%]. CI-AKI was defined as an increase of either 25% or 0.5 mg/dL (44.2 μmoI/L) in serum baseline creatinine level within 72 h following the administration of the contrast agent. A total of 3848 patients were included in the study; mean age 67 years old, 33.9% females, 48.1% with HF, and 16.9% with CI-AKI. In multivariate logistic regression analysis, HF was an independent risk factor for CI-AKI (OR 1.316, p value < 0.05). Among patients with HF, decreased levels of EF (OR 0.985, p value < 0.05) and elevated levels of N-terminal pro b-type natriuretic peptide (NT-proBNP) (OR 1.168, p value < 0.05) were risk factors for CI-AKI. These results were consistent in subgroup analysis. Patients with HFrEF were more likely to develop CI-AKI than those with HFmrEF or HFpEF (OR 0.852, p value = 0.031). Additionally, lower levels of EF were risk factors for CI-AKI in the HFrEF and HFmrEF groups, but not in the HFpEF group. NT-proBNP was an independent risk factor for CI-AKI in the HFrEF, HFmrEF and HFpEF groups. Elevated levels of NT-proBNP are independent risk factors for CI-AKI irrespective of the classification of HF. Lower levels of EF were risk factors for CI-AKI in the HFrEF and HFmrEF groups, but not in the HFpEF group.