Vancomycin therapeutic drug monitoring service quality indices and clinical effectiveness outcomes: A retrospective cohort and clinical audit

IntroductionVancomycin is commonly used for the treatment of complicated infections caused by methicillin-resistant Staphylococcus aureus. The impact of vancomycin therapeutic drug monitoring (TDM) quality indices on clinical outcomes has not been previously explored. ObjectivesThis study aims to relate routine vancomycin TDM service quality indices to clinical effectiveness outcomes and to develop a pragmatic vancomycin-specific TDM quality assessment tool that can be used in quality audits. MethodsA retrospective chart review was conducted on adult non-dialysis vancomycin TDM records documented between January 2014 and October 2016 in three tertiary care hospitals under Hamad Medical Corporation (HMC) in Qatar. Evidence-based criteria and pilot-testing were applied to develop a quality assessment tool. The appropriateness of vancomycin TDM service and clinical outcomes were simultaneously evaluated. ResultsA 13-criterion vancomycin TDM quality assessment tool was developed and used to evaluate 208 TDM records involving 99 patients. The indications for TDM requests were judged appropriate in 77.4% (n = 161) of the records. However, most of the blood samples were deemed to be incorrectly timed (70.7%, n = 147). Inappropriate vancomycin TDM practices compared with appropriate practices were associated with lower therapeutic cure (47.3% vs 75%, P-value = .009). ConclusionsVancomycin TDM requests were justified at HMC. However, inappropriate practices were associated with suboptimal clinical outcomes, signifying the importance of routine quality audits using rigorous evaluation tools. The developed tool can be used to determine setting-specific deficiencies in routine vancomycin TDM practices.