Cystatin C and/or creatinine-based estimated glomerular filtration rate for prediction of vancomycin clearance in long-stay critically ill patients with persistent inflammation, immunosuppression and catabolism syndrome (PICS): a population pharmacokinetics analysis

Performance of Five Estimated Glomerular Filtration Rate Equations in Vietnamese Kidney Transplant Recipients: A Cross-Sectional Study

BACKGROUND

Despite the critical role of glomerular filtration rate (GFR) assessment in monitoring kidney transplants, the most accurate estimate remains uncertain. This study aimed to evaluate the performance of established estimated GFR (eGFR) equations in the Vietnamese population.

METHODS

This cross-sectional study involving 299 Vietnamese kidney transplant recipients (KTRs) compared measured GFR (mGFR), determined using technetium-99m-diethylenetriaminepentaacetate (99mTc-DTPA) renal dynamic scintigraphy, with five eGFR equations (Modification of Diet in Renal Disease [MDRD], Asian modified Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI], CKD-EPI SCysC 2012, CKD-EPI SCr 2021, and CKD-EPI SCr-SCysC 2021). The performances of the five eGFR equations were compared based on bias, P30 accuracy, absolute accuracy, precision, root mean square error (RMSE), concordance correlation coefficient (CCC), and Pearson's correlation coefficient (r), along with their 95% confidence intervals (CIs).

RESULTS

CKD-EPI SCr-SCysC 2021 showed the best performance. The values for median bias, P30 accuracy, absolute accuracy, precision, RMSE, CCC, and r were: 2.57 [1.22; 3.55] mL/min/1.73 m2, 87.6% [83.3; 90.6], 10.0% [8.3; 11.7], 11.29 [9.57; 13.40] mL/min/1.73 m2, 11.54 [10.42; 12.92], 0.787 [0.737; 0.828], and 0.810 [0.759; 0.850], respectively. The MDRD equation did not show significantly lower precision and accuracy than the CKD-EPI SCr-SCysC 2021 equation. All five equations demonstrated improved accuracy in the mGFR ≥ 60 mL/min/1.73 m2 subgroup compared to the mGFR < 60 mL/min/1.73 m2 subgroup.

CONCLUSIONS

CKD-EPI SCr-SCysC 2021 is the most accurate eGFR equation for Vietnamese KTRs. Further studies with larger cohorts and comparisons with gold-standard methods are needed to confirm these findings.

External Evaluation of Longitudinal Population Pharmacokinetic Models of Vancomycin in Patients With Osteoarticular Infections

BACKGROUND

Osteoarticular infections pose a challenge for therapeutic drug monitoring of vancomycin because they often require prolonged treatment. Given the extensive renal elimination of vancomycin, its pharmacokinetic properties are difficult to predict in the later stages of treatment because the risk of nephrotoxicity increases with the duration of treatment. In this study, published longitudinal population pharmacokinetic (popPK) models were externally evaluated in a cohort of patients with osteoarticular infections.

METHODS

A literature search was performed in PubMed/EMBASE and published reviews. The predictive performance of the selected models was assessed through prediction- and simulation-based diagnostics using NONMEM software. Data were collected during both the retrospective and prospective phases, during which prospectively recruited patients provided additional vancomycin concentrations.

RESULTS

The external validation dataset comprised 525 vancomycin concentrations obtained from 73 patients treated for osteoarticular infections at Montréal General Hospital. Two published popPK models that provided different approaches for integrating a longitudinal structure were identified. Both failed to meet the clinically acceptable threshold of imprecision in population predictions. The weighted median absolute prediction error ranged from 34.9% to 48.3% before re-estimation of model parameters and from 33.5% to 35.2% after re-estimation. The re-estimated models tended to underpredict vancomycin concentrations in the later stages of treatment.

CONCLUSIONS

The 2 evaluated models showed poor predictive performance in our local study population. Further studies should explore new strategies to incorporate a longitudinal component and consider other relevant clinical covariates to develop improved longitudinal popPK models for vancomycin.

Comprehensive guidance for antibiotic dosing in obese adults: 2022 update

Drug dosing in obese patients continues to be challenging due to a lack of high-quality evidence to guide dosing recommendations. We first published guidance for antibiotic dosing in obese adults in 2017, in which we critically reviewed articles identified from a broad search strategy to develop dosing recommendations for 35 antimicrobials. In this updated narrative review, we searched Pubmed, Web of Science, and the Cochrane Library using Medical Subject Headings including anti-infectives, specific generic antimicrobial names, obese, pharmacokinetics, and others. We reviewed 393 articles, cross-referenced select cited references, and when applicable, referenced drug databases, package inserts, and clinical trial data to update dosing recommendations for 41 antimicrobials. Most included articles were pharmacokinetic studies, other less frequently included articles were clinical studies (mostly small, retrospective), case reports, and very rarely, guidelines. Pharmacokinetic changes are frequently reported, can be variable, and sometimes conflicting in this population, and do not always translate to a documented difference in clinical outcomes, yet are used to inform dosing strategies. Extended infusions, high doses, and therapeutic drug monitoring remain important strategies to optimize dosing in this population. Additional studies are needed to clinically validate proposed dosing strategies, clarify optimal body size descriptors, dosing weight scalars, and estimation method of renal function in obese patients.

Population pharmacokinetic model of vancomycin in postoperative neurosurgical patients

Objective: Vancomycin is commonly used in postoperative neurosurgical patients for empirical anti-infective treatment due to the low success rate of bacterial culture in cerebrospinal fluid (about 20%) and the high mortality of intracranial infection. At conventional doses, the rate of target achievement for vancomycin trough concentration is low and the pharmacokinetics of vancomycin varies greatly in these patients, which often leads to treatment failure. The objective of this study was to establish a population pharmacokinetic (PPK) model of vancomycin in postoperative neurosurgical patients for precision medicine.

Method: A total of 895 vancomycin plasma concentrations from 560 patients (497 postoperative neurosurgical patients) were retrospectively collected. The model was analyzed by nonlinear mixed effects modeling method. One-compartment model and mixed residual model was employed. The influence of covariates on model parameters was tested by forward addition and backward elimination. Goodness-of-fit, bootstrap and visual predictive check were used for model evaluation. Monte Carlo simulations were employed for dosing strategies with AUC₂₄ targets 400–600.

Result: Estimated glomerular filtration rate (eGFR), body weight (BW) and mannitol had significant influence on vancomycin clearance (CL). eGFR(mL/min)=144×(Scr/a)b×0.993age, for female, a = 0.7, Scr ≤ 0.7 mg/dl, b = −0.329, Scr > 0.7 mg/dl, b = −1.209; for male, a = 0.9, Scr ≤ 0.9 mg/dl, b = −0.411, Scr > 0.9 mg/dl, b = −1.210. Vancomycin clearance was accelerated when co-medicated with mannitol and increased with eGFR and BW. In the final model, the population typical value is 7.98 L/h for CL and 60.2 L for apparent distribution volume, CL (L/h)=7.98×(eGFR/115.2)0.8×(BW/70)0.3×eA, where A = 0.13 when co-medicated with mannitol, otherwise A = 0. The model is stable and effective, with good predictability.

Conclusion: In postoperative neurosurgical patients, a higher dose of vancomycin may be required due to the augmented renal function and the commonly used mannitol, especially in those with high body weight. Our vancomycin PPK model could be used for individualized treatment in postoperative neurosurgical patients.

Chronic Kidney Disease with Mild and Mild to Moderate Reduction in Renal Function and Long-Term Recurrences of Atrial Fibrillation after Pulmonary Vein Cryoballoon Ablation

The aim of this research was to evaluate if patients with chronic kidney disease (CKD) and mild or mild to moderate depression of renal function have an increased risk of atrial fibrillation (AF) recurrences after cryoballoon (CB) ablation. We performed a retrospective analysis of AF patients undergoing pulmonary vein isolation (PVI) by CB. The cohort was divided according to the KDIGO CKD-EPI classification into a (1) normal, (2) mildly decreased, or (3) mild to moderate reduction in estimated glomerular filtration rate (eGFR). Freedom from AF recurrences was the primary endpoint. A total of 1971 patients were included (60 ± 10 years, 29.0% females, 73.6% paroxysmal AF) in the study. Acute success and complication rates were 99.2% and 3.7%, respectively, with no significant differences among the three groups. After a follow-up of 24 months, AF recurrences were higher in the mildly and mild to moderate CKD groups compared to the normal kidney function group (23.4% vs. 28.3% vs. 33.5%, p < 0.05). Mild to moderate CKD was an independent predictor of AF recurrences after the blanking period (hazard ratio:1.38, 95% CI 1.02−1.86, p = 0.037). In conclusion, a multicenter analysis of AF patients treated with cryoablation revealed mild to moderate reductions in renal functions were associated with a higher risk of AF recurrences. Conversely, the procedural success and complication rates were similar in patients with normal, mildly reduced, or mild to moderate reduction in eGFR.