The ratio of pre-dialysis vancomycin trough serum concentration to minimum inhibitory concentration is associated with treatment outcomes in methicillin-resistant Staphylococcus aureus bacteremia

External evaluation of intravenous vancomycin population pharmacokinetic models in adults receiving high-flux intermittent haemodialysis

AIMS

Patients undergoing haemodialysis (HD) are at greater risk of methicillin-resistant Staphylococcus aureus infections requiring intravenous vancomycin. Close vancomycin therapeutic drug monitoring is warranted in HD patients as renal clearance is the primary elimination pathway. Clinically, population pharmacokinetics (popPK) model-informed dosing is commonly used. This study aimed to perform an external evaluation of published vancomycin popPK models developed for adults undergoing high-flux intermittent HD, and to create a dosing nomogram derived from the model that performed best.

METHODS

A literature review was conducted through PubMed and EMBASE to identify relevant popPK models. an external dataset was collected retrospectively from patients of 2 healthcare centres in Quebec, Canada. Selected models were implemented in NONMEM (v7.5; ICON Development Solutions). Predictive performance was assessed through prediction and simulation-based diagnostics.

RESULTS

In total, 2386 vancomycin concentrations were collected from 274 patients and 476 antibiotic courses. Four vancomycin popPK models were selected for evaluation. None of the models demonstrated overall satisfactory or clinically acceptable predictive performance. Nonetheless, Bae et al.'s model performed best with a median prediction error of 16.25% and median absolute prediction error of 34.66%. Different predictive performance was also observed for vancomycin concentrations from samples collected during and between HD sessions.

CONCLUSION

All evaluated models presented poor overall predictive performance. Further studies are required, through existing popPK model parameter re-estimation or new model development, to adequately describe vancomycin pharmacokinetics for our high-flux intermittent HD patient cohort.

Optimize Vancomycin Dose in Surgical Ward Patients with Augmented Renal Clearance Determined by Chronic Kidney Disease Epidemiology Collaboration Equation

Background

In the field of postoperative care, infections caused by Gram-positive bacteria pose a major clinical challenge. Vancomycin is a key therapeutic agent whose efficacy is greatly influenced by renal function, particularly by augmented renal clearance (ARC). The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) estimated glomerular filtration rate (eGFR) is an easy and commonly used method to predict ARC; however, it is not well studied to determine vancomycin dose. In this study, we examined the effectiveness of the CKD-EPI equation in determining ARC and optimizing the dose of vancomycin for surgical ward patients.

Methodology

A retrospective observational study was conducted to examine 158 surgical ward patients receiving vancomycin. Data on demographics, medical history, and vancomycin dosing were collected. Renal function was evaluated using the CKD-EPI equation, with ARC defined as eGFR ≥ 96.5 mL/min/1.73 m2. Vancomycin pharmacokinetics were calculated using the ClinCalc tool.

Results

ARC was in 54% of the patients. Compared with patients without ARC, those with ARC were younger and had lower serum creatinine levels. They also required higher vancomycin doses but had lower trough concentrations and 24-hour area-under-the-curve values. A significant correlation was observed between eGFR and vancomycin clearance, with eGFR > 96.5 mL/min/1.73 m2 necessitating higher vancomycin doses (>45 mg/kg/day) to achieve the desired area under the curve to minimum inhibitory concentration ratio.

Conclusion

For surgical ward patients with CKD-EPI eGFR ≥ 96.5 mL/min/1.73 m2, a vancomycin dosage of >45 mg/kg/day may be recommended to reach effective therapeutic levels. Overall, this study emphasizes the importance of tailoring vancomycin therapy depending on renal function to ensure efficacy and mitigate the risk of antimicrobial resistance in surgical ward patients.

Development and Assessment of Vancomycin Dosing Utilizing AUC/MIC Protocol in Patients With End-Stage Renal Disease (ESRD) on Intermittent Hemodialysis (IHD)

Purpose: Vancomycin is commonly prescribed for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections, including patients with end stage renal disease (ESRD) receiving intermittent hemodialysis (IHD). Infection is the second-leading cause of mortality in this patient population; therefore, optimizing vancomycin dosing is essential. New guidelines recommend using the ratio of area under the curve (AUC)/minimal inhibitory concentration (MIC) dosing with a target of 400-600 to maximize efficacy and minimize vancomycin nephrotoxicity. Summary: A retrospective chart review was performed to assess the current protocol for vancomycin dosing in ESRD patients on IHD at a community hospital in North Mississippi. A protocol was developed for dosing vancomycin utilizing AUC/MIC targets in this patient population. The study included all inpatient adults with ESRD receiving IHD at least 3 times weekly and receiving vancomycin. Data collection occurred in two phases. The first phase of data collection occurred before implementation of the new protocol and assessed the current vancomycin protocol effectiveness. In phase II of data collection, an assessment of the newly developed protocol utilizing similar data collected in phase I was conducted. Conclusions: It is thought that the difference in treatment outcomes and AUC/MIC targets is due to decreased immune function in this population. For this reason, we set our goal pre-dialysis level at 20-25 mg/dL, rather than 17-25 mg/dL, which correlates with an AUC/MIC of 480-600. It is important to quickly achieve therapeutic levels for the patients that do have MRSA to improve outcomes, to sustain these levels, and to reduce adverse events and costs.

Impact of Vancomycin trough levels monitoring on uncomplicated methilcillin-resistant Staphylococcus aureus bacteremia in chronic kidney disease on hemodialysis, retrospective cohort

BACKGROUND

CKD patients on hemodialysis (HD) with Staphylococcus aureus (SA) bacteremia present high morbidity, mortality and increased risk of MRSA. Vancomycin is the antibiotic of choice in these cases, it has a narrow therapeutic margin and inadequate dosage generates a risk of toxicity, therefore, the recommendation is to dosage it through serum levels.

METHODS

This is a retrospective cohort study in 3 hospitals of third level of complexity in the city of Medellin in which there were differences in the measurement and implementation of vancomycin25 dosage based on trough levels (VL) in patients with chronic kidney disease on hemodialysis (CKD- HD) with uncomplicated bacteremia based infection by methilcillin-resistant Staphyloccocus aureus (MRSA). The primary outcome was the composite of hospital mortality, clinical response (fever, hemodynamic instability and altered consciousness), complications associated with bacteremia, or bacteriological response failure (positive cultures at first week follow-up) at 7 days. The composite variables were analyzed individually as secondary outcomes.

RESULTS

The main unadjusted outcome (OR 1.3, CI 0.6 - 2.7) and adjusted for age, Charlson index, loading dose, initial dose, dosing frequency and MIC to vancomycin (OR 1.2, CI 0.5 - 2.7). Regarding adjusted secondary outcomes: clinical response (OR 1.4 CI 0.3 - 5.8), death (OR 1.3 CI 0.3 - 4.6) and complications (OR 0.9, CI 0.37 - 2.2).

CONCLUSIONS

We conclude that the measurement of trough levels in patients with HD-CKD does not modify the composite outcome. The main limitation is the sample size and type of study, randomized control trials may be required to confirm the results presented.

Is It Still Beneficial to Monitor the Trough Concentration of Vancomycin? A Quantitative Meta-Analysis of Nephrotoxicity and Efficacy

This study conducted a quantitative meta-analysis to investigate the association of vancomycin indicators, particularly area under the curve over 24 h (AUC24) and trough concentrations (Ctrough), and their relationship with both nephrotoxicity and efficacy. Literature research was performed in PubMed and Web of Science on vancomycin nephrotoxicity and efficacy in adult inpatients. Vancomycin Ctrough, AUC24, AUC24/minimum inhibitory concentration (MIC), nephrotoxicity evaluation and treatment outcomes were extracted. Logistic regression and Emax models were conducted, stratified by evaluation criterion for nephrotoxicity and primary outcomes for efficacy. Among 100 publications on nephrotoxicity, 29 focused on AUC24 and 97 on Ctrough, while of 74 publications on efficacy, 27 reported AUC24/MIC and 68 reported Ctrough. The logistic regression analysis indicated a significant association between nephrotoxicity and vancomycin Ctrough (odds ratio = 2.193; 95% CI 1.582-3.442, p < 0.001). The receiver operating characteristic curve had an area of 0.90, with a cut-off point of 14.55 mg/L. Additionally, 92.3% of the groups with a mean AUC24 within 400-600 mg·h/L showed a mean Ctrough of 10-20 mg/L. However, a subtle, non-statistically significant association was observed between the AUC24 and nephrotoxicity, as well as between AUC24/MIC and Ctrough concerning treatment outcomes. Our findings suggest that monitoring vancomycin Ctrough remains a beneficial and valuable approach to proactively identifying patients at risk of nephrotoxicity, particularly when Ctrough exceeds 15 mg/L. Ctrough can serve as a surrogate for AUC24 to some extent. However, no definitive cut-off values were identified for AUC24 concerning nephrotoxicity or for Ctrough and AUC24/MIC regarding efficacy.

Model-Informed Precision Dosing of Vancomycin in Adult Patients Undergoing Hemodialysis

Model-informed precision dosing (MIPD) maximizes the probability of successful dosing in patients undergoing hemodialysis. In these patients, area under the concentration-time curve (AUC)-guided dosing is recommended for vancomycin. However, this model is yet to be developed. The purpose of this study was to address this issue. The overall mass transfer-area coefficient (KoA) was used for the estimation of vancomycin hemodialysis clearance. A population pharmacokinetic (popPK) model was developed, resulting in a fixed-effect parameter for nonhemodialysis clearance of 0.316 liters/h. This popPK model was externally evaluated, with a resulting mean absolute error of 13.4% and mean prediction error of -0.17%. KoA-predicted hemodialysis clearance was prospectively evaluated for vancomycin (n = 10) and meropenem (n = 10), with a correlation equation being obtained (slope of 1.099, intercept of 1.642; r = 0.927, P < 0.001). An experimental evaluation using an in vitro hemodialysis circuit validated the developed model of KoA-predicted hemodialysis clearance using vancomycin, meropenem, vitamin B6, and inulin in 12 hemodialysis settings. This popPK model indicated a maximum a priori dosing for vancomycin-a loading dose of 30 mg/kg, which achieves the target AUC for 24 h after first dose with a probability of 93.0%, ensured by a predialysis concentration of >15 μg/mL. Maintenance doses of 12 mg/kg after every hemodialysis session could achieve the required exposure, with a probability of 80.6%. In conclusion, this study demonstrated that KoA-predicted hemodialysis clearance may lead to an upgrade from conventional dosing to MIPD for vancomycin in patients undergoing hemodialysis.

Optimal Sampling Strategy and Threshold of Serum Vancomycin Concentration in Elderly Japanese Patients Undergoing High-Flux Hemodialysis

BACKGROUND

The optimal sampling points and thresholds for initial serum vancomycin (VCM) concentrations have not been determined in hemodialysis (HD) patients. To clarify this, multiple blood tests were performed, and the correlations between VCM concentrations at several sampling points and the area under the concentration-time curve for 24 hours (AUC24h) were analyzed.

METHODS

A single-center, prospective observational study was conducted. Patients with end-stage renal failure who received VCM treatment while undergoing chronic maintenance HD were enrolled in this study. HD was performed using a high-flux membrane as the dialyzer. After VCM administration, 7 points were sampled between the first and second HD. The AUC24h after the end of the first HD (AUC0-24) and that before the end of the second HD (AUC24-48) were calculated using the linear trapezoidal method. Correlation analysis and simple regression analysis between AUC24h and serum concentrations were performed at each sampling point.

RESULTS

Nine patients were evaluated. Strong correlations were found between AUC24-48 and serum concentrations at 24 hours after the initiation of VCM treatment following the first HD (C24h, R = 0.983 and P < 0.001), between AUC0-24 and C24h (R = 0.967 and P < 0.001), and between AUC24-48 and serum concentration just before the second HD (Cpre(HD2), R = 0.965 and P < 0.001). Regression equations with high coefficients of determination (R2 > 0.9) were obtained, and a C24h of ≥18.0 mg/L and a Cpre(HD2) of ≥16.5 mg/L were required to achieve an AUC24-48 value of ≥400 mg·h/L. In addition, a C24h of ≤23.3 mg/L was estimated to satisfy the AUC0-24 range of ≤600 mg·h/L.

CONCLUSIONS

C24h and Cpre(HD2) are optimal sampling points for predicting VCM-AUC24h in HD patients.

An updated vancomycin dosing protocol for initiating therapy in patients undergoing intermittent high-flux hemodialysis

DISCLAIMER

In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time.

PURPOSE

To design an updated vancomycin dosing protocol for initiating therapy in patients undergoing chronic intermittent high-flux hemodialysis (iHFHD) that is congruent with the revised 2020 consensus guidelines for therapeutic drug monitoring (TDM).

METHODS

Monte Carlo simulation methods were used to study vancomycin dosing for patients on iHFHD. Vancomycin regimens were constructed as intravenous infusions (for intradialytic administration) of a loading dose and maintenance doses 3 times weekly during subsequent dialysis sessions. Vancomycin plasma concentrations were simulated, and the probability of target attainment (PTA) for a 24-hour area under the time-concentration curve (AUC24) of 400 to 700 mg • h/L was determined. Standardized weight-based (ie, dose-banding) regimens were investigated, and an optimized protocol was selected based on TDM target attainment and practical considerations for use in the dialysis setting.

RESULTS

The proposed vancomycin dosing protocol (for intradialytic administration) specifies 3 regimens: (1) a 1,500-mg loading dose and 750-mg maintenance doses for patients weighing 50 kg to 69 kg; (2) a 2,000-mg loading dose and 1,000-mg maintenance doses for patients weighing 70 kg to 89 kg; and (3) a 2,500-mg loading dose and 1,250-mg maintenance doses for patients weighing 90 kg to 110 kg. In a simulated hemodialysis population (n = 1,000), the proposed protocol delivered median (interquartile range [IQR]) loading and maintenance doses of 25.0 (23.4-26.6) mg/kg and 12.5 (11.8-13.3) mg/kg, respectively. The PTA for an AUC24 of 400 to 700 mg • h/L was 74.7% on day 1 and 70.8% on day 8, with less than 10% of values exceeding the target range.

CONCLUSION

Our proposed dosing protocol for patients undergoing iHFHD offers an updated and practical approach for initiating vancomycin therapy that can be optimized with early TDM.

Clinical Practice Guidelines for Therapeutic Drug Monitoring of Vancomycin in the Framework of Model-Informed Precision Dosing: A Consensus Review by the Japanese Society of Chemotherapy and the Japanese Society of Therapeutic Drug Monitoring

Background: To promote model-informed precision dosing (MIPD) for vancomycin (VCM), we developed statements for therapeutic drug monitoring (TDM). Methods: Ten clinical questions were selected. The committee conducted a systematic review and meta-analysis as well as clinical studies to establish recommendations for area under the concentration-time curve (AUC)-guided dosing. Results: AUC-guided dosing tended to more strongly decrease the risk of acute kidney injury (AKI) than trough-guided dosing, and a lower risk of treatment failure was demonstrated for higher AUC/minimum inhibitory concentration (MIC) ratios (cut-off of 400). Higher AUCs (cut-off of 600 μg·h/mL) significantly increased the risk of AKI. Although Bayesian estimation with two-point measurement was recommended, the trough concentration alone may be used in patients with mild infections in whom VCM was administered with q12h. To increase the concentration on days 1–2, the routine use of a loading dose is required. TDM on day 2 before steady state is reached should be considered to optimize the dose in patients with serious infections and a high risk of AKI. Conclusions: These VCM TDM guidelines provide recommendations based on MIPD to increase treatment response while preventing adverse effects.

Vancomycin pharmacokinetics in patients treated with intermittent haemodialysis based on therapeutic drug monitoring

Vancomycin is frequently used in haemodialysis (HD) patients but generally accepted target serum ranges and dosing strategy are still lacking in this group. Based on retrospective analysis of data from 118 HD patients treated with vancomycin the interdialytic elimination constant (K_e), apparent volume of distribution (Vd) and dialysis efficacy were calculated. The influence of possible clinical variables on the pharmacokinetic parameters of vancomycin have been tested. The median of K_e in interdialytic periods, corresponding half-life and Vd were 0.0073 h^-1, 95.0 h and 0.87 L/kg, respectively. We found significant positive correlation between time in dialysis program and K_e. The Vd correlated best with lean body mass (LBM). For high- and low flux membrane HD of 4 hours duration the decline in vancomycin levels was 20.88% and 12.86%, respectively. Based on these data loading dose for vancomycin in HD patient should be calculated as 24.483 × LBM (kg) + 455 mg. The utility of this equation for entire HD population should be also verified prospectively.

The monitoring of vancomycin: a systematic review and meta-analyses of area under the concentration-time curve-guided dosing and trough-guided dosing

Background

This systematic review and meta-analysis explored the relationship between vancomycin (VCM) monitoring strategies and VCM effectiveness and safety.

Methods

We conducted our analysis using the MEDLINE, Web of Sciences, and Cochrane Register of Controlled Trials electronic databases searched on August 9, 2020. We calculated odds ratios (ORs) and 95% confidence intervals (CIs).

Results

Adult patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia with VCM trough concentrations ≥15 μg/mL had significantly lower treatment failure rates (OR 0.63, 95% CI 0.47–0.85). The incidence of acute kidney injury (AKI) increased with increased trough concentrations and was significantly higher for trough concentrations ≥20 μg/mL compared to those at 15–20 μg/mL (OR 2.39, 95% CI 1.78–3.20). Analysis of the target area under the curve/minimum inhibitory concentration ratios (AUC/MIC) showed significantly lower treatment failure rates for high AUC/MIC (cut-off 400 ± 15%) (OR 0.28, 95% CI 0.18–0.45). The safety analysis revealed that high AUC value (cut-off 600 ± 15%) significantly increased the risk of AKI (OR 2.10, 95% CI 1.13–3.89). Our meta-analysis of differences in monitoring strategies included four studies. The incidence of AKI tended to be lower in AUC-guided monitoring than in trough-guided monitoring (OR 0.54, 95% CI 0.28–1.01); however, it was not significant in the analysis of mortality.

Conclusions

We identified VCM trough concentrations and AUC values that correlated with effectiveness and safety. Furthermore, compared to trough-guided monitoring, AUC-guided monitoring showed potential for decreasing nephrotoxicity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-05858-6.

Evaluation and Development of Vancomycin Dosing Schemes to Meet New AUC/MIC Targets in Intermittent Hemodialysis Using Monte Carlo Simulation Techniques

Published vancomycin dosing recommendations for patients receiving maintenance hemodialysis were not designed to meet newly recommended 24-hour area under the curve/minimum inhibitory concentration (AUC_24h /MIC) pharmacokinetic/pharmacodynamic targets. The aims of this study were to predict pharmacokinetic/pharmacodynamic target attainment rates with a commonly used vancomycin regimen and to design a new dosing scheme incorporating therapeutic drug monitoring (TDM) to maximize target attainment in patients receiving vancomycin and hemodialysis with high- or low-flux hemodialyzers. Vancomycin pharmacokinetic- and dialysis-specific parameters were incorporated into Monte Carlo simulations (MCS). A commonly used vancomycin regimen was modeled to determine its likelihood of attaining AUC_24h /MIC targets for 1 week of thrice-weekly hemodialysis treatments. MCS was then used to develop optimal initial vancomycin dosing for patients receiving intradialytic or postdialytic vancomycin administration with either high- or low-flux hemodialyzers. Finally, a new MCS model incorporating TDM was built to further optimize the probability of pharmacokinetic/pharmacodynamic target attainment. Traditional vancomycin dosing methods are unlikely to meet AUC_24h /MIC targets. Vancomycin doses necessary to attain AUC_24h /MIC targets are significantly influenced by hemodialyzer permeability and whether vancomycin is administered intradialytically or after hemodialysis. Depending on dialyzer type and whether vancomycin is administered during or after hemodialysis, loading doses of 25 to 35 mg/kg followed by maintenance doses of 7.5 to 15 mg/kg are necessary to reach minimum AUC_24h /MIC targets in 90% of virtual patients. For a 3-day interdialytic period, a 30% higher maintenance dose is required to maintain target attainment. Dosing based on a single vancomycin serum concentration obtained prior to the second dialysis session greatly enhances the probability of target attainment.

Validation of a Weight Threshold-Based Vancomycin Dosing Protocol for Patients Undergoing Intermittent Hemodialysis

BACKGROUND

Patients receiving intermittent hemodialysis (IHD) are at high risk of acquiring gram-positive infections, which are often treated with IV vancomycin. Despite frequent use of vancomycin in the IHD setting, there is variability in dosing and monitoring practices among clinicians at the study institution. There is also a paucity of evidence regarding optimal vancomycin dosing to achieve target pre-IHD serum concentration.

OBJECTIVES

The primary objective was to compare the percentage of treatment courses with a serum vancomycin concentration between 15 and 20 mg/L, measured before the third IHD session, before and after implementation of a weight threshold-based dosing protocol. The secondary objectives were to compare the percentage of treatment courses with a pre-third IHD vancomycin concentration between 10 and 22 mg/L and the number of vancomycin measurements per treatment day, before and after protocol implementation.

METHODS

This quasi-experimental, single-centre study included inpatients and outpatients who underwent IHD and received at least 2 IV doses of vancomycin, with vancomycin being measured in an appropriately drawn sample before the third IHD session. Before protocol implementation, vancomycin dosing was at the clinician's discretion (usual care). After protocol implementation, each patient received a loading dose of 1000, 1500, or 2000 mg and a maintenance dose of 500, 750, or 1000 mg, depending on body weight.

RESULTS

The percentage of treatment courses with a pre-third IHD vancomycin concentration between 15 and 20 mg/L was greater after implementation of the protocol than with usual care, but the difference was nonsignificant (44% [8/18] versus 20% [3/15], p = 0.27). However, the percentage of treatment courses with a pre-third IHD vancomycin concentration between 10 and 22 mg/L was significantly higher after protocol implementation (94% [17/18] versus 53% [8/15], p = 0.012). There was no difference in the median number of vancomycin measurements per treatment day before and after protocol implementation (0.133 versus 0.125, p = 0.99).

CONCLUSIONS

At the study institution, the likelihood of achieving recommended vancomycin concentration increased (relative to previous practice) after implementation of a simplified vancomycin dosing protocol for patients undergoing IHD.