Practices, Knowledge, and Attitudes of Nephrologists Towards Prescribing and Monitoring Vancomycin at Dialysis Centers

BACKGROUND

Vancomycin dosing protocols are varied in the literature for hemodialysis patients. This study sought to determine nephrologists' practices, knowledge, attitudes, and barriers toward prescribing and monitoring vancomycin at dialysis centers.

METHODS

A cross-sectional and multi-center study was conducted in Kuwait using a validated self-administered questionnaire among 168 nephrologists. Descriptive and comparative analyses were performed using SPSS (version 28).

RESULTS

The response rate was 75% (n = 126). Over half of nephrologists frequently prescribed a vancomycin loading dose of 1000 mg (53.2%) and a maintenance dose of 500 mg (51.6%) to all patients. Their overall median (IQR) percentage knowledge about the therapeutic monitoring of vancomycin was 66.7% (33.3) and was found to be higher in nephrologists aged ≤ 40 years and in registrars/senior registrars (p < 0.05). Their overall median (IQR) attitude score was 4.0 (1.0) [positive attitude]. Nephrologists with > 15 years of practice experience expressed higher attitudes (p < 0.05). The top two perceived barriers were a lack of clear local hospital/national guidelines (60.3%) for vancomycin dosing in dialysis and inconsistencies among different dosing references and guidelines (51.6%).

CONCLUSION

Findings showed that nephrologists have varying practices, moderate knowledge, and positive attitudes toward prescribing and monitoring vancomycin and highlight the need for interventions to overcome the perceived barriers.

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.

Predicting Maintenance Doses of Vancomycin for Hospitalized Patients Undergoing Hemodialysis

BACKGROUND

Methicillin-resistant Staphylococcus aureus is a leading cause of death in patients undergoing hemodialysis. However, controversy exists about the optimal dose of vancomycin that will yield the recommended pre-hemodialysis serum concentration of 15-20 mg/L.

OBJECTIVE

To develop a data-driven model to optimize the accuracy of maintenance dosing of vancomycin for patients undergoing hemodialysis.

METHODS

A prospective observational cohort study was performed with 164 observations obtained from a convenience sample of 63 patients undergoing hemodialysis. All vancomycin doses were given on the floor after completion of a hemodialysis session. Multivariate linear generalized estimating equation analysis was used to examine independent predictors of pre-hemodialysis serum vancomycin concentration.

RESULTS

Pre-hemodialysis serum vancomycin concentration was independently associated with maintenance dose (B = 0.658, p < 0.001), baseline pre-hemodialysis serum concentration of the drug (B = 0.492, p < 0.001), and interdialytic interval (B = -2.133, p < 0.001). According to the best of 4 models that were developed, the maintenance dose of vancomycin required to achieve a pre-hemodialysis serum concentration of 15-20 mg/L, if the baseline serum concentration of the drug was also 15-20 mg/L, was 5.9 mg/kg with interdialytic interval of 48 h and 7.1 mg/kg with interdialytic interval of 72 h. However, if the baseline pre-hemodialysis serum concentration was 10-14.99 mg/L, the required dose increased to 9.2 mg/kg with an interdialytic interval of 48 h and 10.0 mg/kg with an interdialytic interval of 72 h.

CONCLUSIONS

The maintenance dose of vancomycin varied according to baseline pre-hemodialysis serum concentration of the drug and interdialytic interval. The current practice of targeting a pre-hemodialysis concentration of 15-20 mg/L may be difficult to achieve for the majority of patients undergoing hemodialysis.