THE CLINICAL PRACTICE OF VANCOMYCIN DOSING AND MONITORING, AND FACTORS AFFECTING LEVELS AMONGST ONCOLOGY AND CARDIOLOGY PATIENTS IN QATAR: A RETROSPECTIVE ANALYSIS

Shereen Elazzazy*, Khalid Al Siyab, Amir Nounou, Ahmed Mahfouz, Prem Chandra, Manal Zaidan

The paper focuses on the assessment of current vancomycin (VCM) use in National Centre for Cancer Care and Research (NCCCR) and Heart Hospital (HH) (the only tertiary care specialty hospitals in Qatar) which are 2 out of 8 teaching hospitals in Hamad Medical Corporation the main and largest healthcare organization in Qatar. Primary objectives were to assess the current vancomycin use for cancer and cardiology patients among Qatar population admitted to National Centre for Cancer Care and Research (NCCCR) and Heart Hospital (HH), and to explicate the factors that affected VCM serum trough levels, secondary objective was to access the need to develop and establish a guideline, which is essential to assure the standardization of practice and meets the unique needs of our patients’ population. A retrospective cross sectional study was conducted to review patients’ medical record of the clinical practice of VCM use in two hospitals the NCCCR and HH. We reviewed all VCM level determinations performed during the 12-month (from January, to December, 2012) study period that met inclusion criteria. We retrospectively analyzed the trough and peak concentrations (if taken) of vancomycin in 206 hospitalized patients (between 16 to 92 years of age) with VCM treatment episodes. The relationship between dose and concentration of drug, dose and body weight/ CrCl were established by regression analysis. Statistical analyses were done using excel and statistical packages SPSS 19.0. This multicenter study shows that 71% (118/167) of patients received a total daily dose of 2000 mg/ day (1000 mg every 12 hours over 60 minutes); this dose was common among different body weights (40-145 kg) and estimated CrCl (11-139 ml/min) values, dose selections was not considered based on body weight and/ or CrCl, therefore no linear correlation were shown between VCM trough and body weight/ CrCl. Initial loading dose of VCM was not considered for any of the patients included in the study (n=167). Only 16% of trough concentrations presented therapeutic levels, therefore a high percentage of patients was found to have sub-therapeutic or supra-therapeutic concentrations, furthermore 31% of patients had no trough levels. No linear correlation was found between patients body weight and the total daily dose (r=0.037). Only 39% (65/167) had cultures done, out of which7.8% (13/167) showed various gram positive bacteria (MRSA, MRSE, other coagulase-negative staphylococci, or Enterococcus) were isolated. Multiple areas of improvement were identified in dosing and monitoring of VCM in NCCCR and HH, evidence based guidelines are urgently required with the direct involvement of Clinical Pharmacists and Infectious Disease department to apply the optimal VCM initial dose based on creatinine clearance (CrCl) and body weight (BW) to minimize sub-therapeutic or supra-therapeutic trough levels.