Therapeutic drug monitoring (TDM) has become standard clinical practice for gentamicin, amikacin, and vancomycin to optimize efficacy and reduce toxicity. TDM after the first dose of antibiotic was adopted in our institution. This study aims to evaluate if target therapeutic drug concentrations could be achieved more rapidly in patients with TDM performed after the first dose of gentamicin, amikacin, or vancomycin compared to TDM at steady state. A single‐center retrospective cohort study was conducted at KK Women's and Children's Hospital, Singapore. Patients aged 1 month to 18 years old who received amikacin, gentamicin, or vancomycin between October 2012 to March 2016 and had at least 2 serum drug concentrations done within the same dosing interval were included. The primary objective was to compare the time taken to achieve target serum drug concentrations between first‐dose and steady‐state TDM. A total of 334 patients on amikacin, 211 patients on gentamicin, and 140 patients on vancomycin were included. Using Kaplan‐Meier analysis, the median number of days to optimize therapy was significantly shorter after first‐dose TDM was performed for amikacin (first dose, 1.51 [95% confidence interval (CI), 1.44‐1.89] days vs steady state, 2.85 [95%CI, 2.50‐3.25] days; P < .01] and gentamicin (first dose, 1.66 [95%CI, 1.25‐2.08] days vs steady state, 3.54 [95%CI, 2.40‐4.75] days; P < .01] but not vancomycin (first dose, 1.34 [95%CI, 1.06‐1.52] days vs steady state, 1.42 [95%CI, 1.26‐1.59] days; P = .99]. First‐dose TDM for gentamicin and amikacin resulted in faster attainment of target serum concentrations but did not for vancomycin. Further validation of its impact on actual clinical outcomes may be required.

Background Oral anticoagulation with warfarin is the cornerstone therapy in atrial fibrillation (AF) for stroke prevention. Multi-disciplinary anticoagulation management services have been shown to be cost-effective in the United States, Hong Kong and Thailand, but the findings are not readily generalizable to Singapore's healthcare system. Objective This study aimed to evaluate the cost-effectiveness of pharmacist-managed anticoagulation clinic (ACC) compared with usual care (UC) for the management of older adults with AF receiving oral anticoagulation with warfarin. Setting Pharmacist-managed ACC in an academic medical centre. Method A Markov model with 3-month cycle length and 30-year time horizon compared costs and quality-adjusted life-years (QALYs) of ACC and UC from the patient's and healthcare provider's perspectives. Four pathways based on time in therapeutic range (TTR) were: ACC TTR < 70 %, ACC TTR ≥ 70 %, UC TTR < 70 % and UC TTR ≥ 70 %. A hypothetical cohort of 70-year-old Singaporean AF patients receiving warfarin was utilised. Local data from national disease registries, patient surveys and hospital databases were used. When local data was not available, published studies on Asian populations were utilized when available. One-way sensitivity analyses and probabilistic sensitivity analyses were performed to account for uncertainties. Costs and QALYs were discounted annually by 3 %. Main outcome measure Costs and QALYs of ACC and UC. Results Pharmacist-managed ACC was found to dominate UC in all comparisons. It improved effectiveness by 0.19 and 0.13 QALYs at TTR < 70 % and TTR ≥ 70 % respectively compared with UC. From the patient's perspective, ACC reduced costs by SG$1222.67 (€1110.24) for TTR < 70 % and SG$1008.16 (€915.46) for TTR ≥ 70 %. Similar trends were observed from the healthcare provider's perspective, with ACC reducing costs by SG$1444.79 (€1311.94) for TTR < 70 % and SG$1269.17 (€1152.46) for TTR ≥ 70 % compared with UC. The results were robust to variations of the parameters over their plausible ranges in one-way sensitivity analyses. Probabilistic sensitivity analyses demonstrated that ACC was cost-effective more than 79 % of the time from both perspectives at a willingness-to-pay threshold of SG$69,050 (€62,701) per QALY. Conclusion Pharmacist-managed ACC is more effective and less costly compared with UC regardless of the quality of anticoagulation therapy. The findings support the current body of evidence demonstrating the cost-effectiveness of ACC.