The experiences and perspectives of people with gout on urate self-monitoring.

INTRODUCTION: Gout management remains suboptimal despite safe and effective urate-lowering therapy. Self-monitoring of urate may improve gout management, however, the acceptability of urate self-monitoring by people with gout is unknown. The aim of this study was to explore the experiences of urate self-monitoring in people with gout. METHODS: Semistructured interviews were conducted with people taking urate-lowering therapy (N = 30) in a 12-month trial of urate self-monitoring in rural and urban Australia. Interviews covered the experience of monitoring and its effect on gout self-management. Deidentified transcripts were analysed thematically. RESULTS: Participants valued the ability to self-monitor and gain more understanding of urate control compared with the annual monitoring ordered by their doctors. Participants indicated that self-monitoring at home was easy, convenient and informed gout self-management behaviours such as dietary modifications, hydration, exercise and medication routines. Many participants self-monitored to understand urate concentration changes in response to feeling a gout flare was imminent or whether their behaviours, for example, alcohol intake, increased the risk of a gout flare. Urate concentrations were shared with doctors mainly when they were above target to seek management support, and this led to allopurinol dose increases in some cases. CONCLUSION: Urate self-monitoring was viewed by people with gout as convenient and useful for independent management of gout. They believed self-monitoring achieved better gout control with a less restricted lifestyle. Urate data was shared with doctors at the patient's discretion and helped inform clinical decisions, such as allopurinol dose changes. Further research on implementing urate self-monitoring in routine care would enable an evaluation of its impact on medication adherence and clinical outcomes, as well as inform gout management guidelines. PATIENT OR PUBLIC CONTRIBUTION: One person with gout, who was not a participant, was involved in the study design by providing feedback and pilot testing the semistructured interview guide. In response to their feedback, subsequent modifications to the interview guide were made to improve the understandability of the questions from a patient perspective. No additional questions were suggested.

Evaluation of Published Population Pharmacokinetic Models to Inform Tacrolimus Therapy in Adult Lung Transplant Recipients.

BACKGROUND: The applicability of currently available tacrolimus population pharmacokinetic models in guiding dosing for lung transplant recipients is unclear. In this study, the predictive performance of relevant tacrolimus population pharmacokinetic models was evaluated for adult lung transplant recipients. METHODS: Data from 43 lung transplant recipients (1021 tacrolimus concentrations) administered an immediate-release oral formulation of tacrolimus were used to evaluate the predictive performance of 17 published population pharmacokinetic models for tacrolimus. Data were collected from immediately after transplantation up to 90 days after transplantation. Model performance was evaluated using (1) prediction-based assessments (bias and imprecision) of individual predicted tacrolimus concentrations at the fourth dosing based on 1 to 3 previous dosings and (2) simulation-based assessment (prediction-corrected visual predictive check; pcVPC). Both assessments were stratified based on concomitant azole antifungal use. Model performance was clinically acceptable if the bias was within ±20%, imprecision was ≤20%, and the 95% confidence interval of bias crossed zero. RESULTS: In the presence of concomitant antifungal therapy, no model showed acceptable performance in predicting tacrolimus concentrations at the fourth dosing (n = 33), and pcVPC plots displayed poor model fit to the data set. However, this fit slightly improved in the absence of azole antifungal use, where 4 models showed acceptable performance in predicting tacrolimus concentrations at the fourth dosing (n = 33). CONCLUSIONS: Although none of the evaluated models were appropriate in guiding tacrolimus dosing in lung transplant recipients receiving concomitant azole antifungal therapy, 4 of these models displayed potential applicability in guiding dosing in recipients not receiving concomitant azole antifungal therapy. However, further model refinement is required before the widespread implementation of such models in clinical practice.

Geographic variation in sodium-glucose cotransporter 2 inhibitor and glucagon-like peptide-1 receptor agonist use in people with type 2 diabetes in New South Wales, Australia.

AIM: Sodium-glucose cotransporter 2 inhibitors (SGLT2is) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) improve glycaemic control and cardio-renal outcomes for people with type 2 diabetes (T2D). However, geographic and socio-economic variation in use is not well understood. METHODS: We identified 367 829 New South Wales residents aged ≥40 years who dispensed metformin in 2020 as a proxy for T2D. We estimated the prevalence of use of other glucose-lowering medicines among people with T2D and the prevalence of SGLT2i and GLP-1RA use among people using concomitant T2D therapy (i.e. metformin + another glucose-lowering medicine). We measured the prevalence by small-level geography, stratified by age group, and characterized by remoteness and socio-economic status. RESULTS: The prevalence of SGLT2i (29.7%) and GLP-1RA (8.3%) use in people with T2D aged 40-64 increased with geographic remoteness and in areas of greater socio-economic disadvantage, similar to other glucose-lowering medicines. The prevalence of SGLT2i (55.4%) and GLP-1RA (15.4%) among people using concomitant T2D therapy varied across geographic areas, with lower SGLT2i use in more disadvantaged areas and localized areas of high GLP-1RA use (2.5 times the median). Compared with people aged 40-64 years, the prevalence of SGLT2i and GLP-1RA use was lower in older age groups, but with similar patterns of variation across geographic areas. CONCLUSIONS: The prevalence of SGLT2i and GLP-1RA use varied by geography, probably reflecting a combination of system- and prescriber-level factors. Socio-economic variation in GLP-1RA use was overshadowed by localized patterns of prescribing. Continued monitoring of variation can help shape interventions to optimize use among people who would benefit the most.

Patient-Led Urate Self-Monitoring to Improve Clinical Outcomes in People With Gout: A Feasibility Study.

OBJECTIVE: Self-monitored point-of-care urate-measuring devices are an underexplored strategy to improve adherence to urate-lowering therapy and clinical outcomes in gout. This study observed patient-led urate self-monitoring practice and assessed its influence on allopurinol adherence, urate control, and health-related quality of life. METHODS: People with gout (n = 31) and prescribed allopurinol self-monitored their urate concentrations (HumaSens2.0plus) at baseline and thereafter monthly for 12 months (3 months per quarter). Adherence to allopurinol was measured using medication event monitoring technology (Medication Event Monitoring System cap). Time spent below the target urate concentration (<0.36 mmol/L) was determined. Health-related quality of life was measured using a survey (EuroQoL EQ-5D-5L). Gout flares were recorded. Two-tailed Spearman correlation and the Wilcoxon matched-pairs signed-rank test (P < 0.05) were used for statistical comparisons. RESULTS: Most participants were male (94%) and had urate concentrations below the target (74%) at baseline. Overall, seven participants demonstrated repeated periods of "missed doses" (two or fewer allopurinol doses missed consecutively) and "drug holidays" (three or more missed doses). Most participants (94%) persisted with allopurinol. Time spent within the target urate concentration increased 1.3-fold (from 79% to 100%; P = 0.346), and the incidence of gout flares decreased 1.6-fold (from 8 to 5; P = 0.25) in the final quarter compared to that in the first quarter of the study. Health-related quality of life was reduced for participants reporting at least one gout flare (median utility values 0.9309 vs 0.9563, P = 0.04). CONCLUSION: Patient-led urate self-monitoring may support the maintenance of allopurinol adherence and improve urate control, thus reducing the incidence of gout flares. Further research on patient-led urate self-monitoring in a randomized controlled study is warranted.

Drug-Drug Interactions and Actual Harm to Hospitalized Patients: A Multicentre Study Examining the Prevalence Pre- and Post-Electronic Medication System Implementation.

INTRODUCTION: Drug-drug interactions (DDIs) have potential to cause patient harm, including lowering therapeutic efficacy. This study aimed to (i) determine the prevalence of potential DDIs (pDDIs); clinically relevant DDIs (cDDIs), that is, DDIs that could lead to patient harm, taking into account a patient's individual clinical profile, drug effects and severity of potential harmful outcome; and subsequent actual harm among hospitalized patients and (ii) examine the impact of transitioning from paper-based medication charts to electronic medication management (eMM) on DDIs and patient harms. METHODS: This was a secondary analysis of the control arm of a controlled pre-post study. Patients were randomly selected from three Australian hospitals. Retrospective chart review was conducted before and after the implementation of an eMM system, without accompanying clinical decision support alerts for DDIs. Harm was assessed by an expert panel. RESULTS: Of 1186 patient admissions, 70.1% (n = 831) experienced a pDDI, 42.6% (n = 505) a cDDI and 0.9% (n = 11) an actual harm in hospital. Of 15,860 pDDIs identified, 27.0% (n = 4285) were classified as cDDIs. The median number of pDDIs and cDDIs per 10 drugs were 6 [interquartile range (IQR) 2-13] and 0 (IQR 0-2), respectively. In cases where a cDDI was identified, both drugs were 44% less likely to be co-administered following eMM (adjusted odds ratio 0.56, 95% confidence interval 0.46-0.73). CONCLUSION: Although most patients experienced a pDDI during their hospital stay, less than one-third of pDDIs were clinically relevant. The low prevalence of harm identified raises questions about the value of incorporating DDI decision support into systems given the potential negative impacts of DDI alerts.

Qualitative study of challenges with recruitment of hospitals into a cluster controlled trial of clinical decision support in Australia.

OBJECTIVE: To identify barriers to hospital participation in controlled cluster trials of clinical decision support (CDS) and potential strategies for addressing barriers. DESIGN: Qualitative descriptive design comprising semistructured interviews. SETTING: Five hospitals in New South Wales and one hospital in Queensland, Australia. PARTICIPANTS: Senior hospital staff, including department directors, chief information officers and those working in health informatics teams. RESULTS: 20 senior hospital staff took part. Barriers to hospital-level recruitment primarily related to perceptions of risk associated with not implementing CDS as a control site. Perceived risks included reductions in patient safety, reputational risk and increased likelihood that benefits would not be achieved following electronic medical record (EMR) implementation without CDS alerts in place. Senior staff recommended clear communication of trial information to all relevant stakeholders as a key strategy for boosting hospital-level participation in trials. CONCLUSION: Hospital participation in controlled cluster trials of CDS is hindered by perceptions that adopting an EMR without CDS is risky for both patients and organisations. The improvements in safety expected to follow CDS implementation makes it challenging and counterintuitive for hospitals to implement EMR without incorporating CDS alerts for the purposes of a research trial. To counteract these barriers, clear communication regarding the evidence base and rationale for a controlled trial is needed.

Estimation of adherence to urate-lowering therapy in people living with gout using Australia's Pharmaceutical Benefits Scheme and patient-reported dosing.

AIMS: The aim of this study was to estimate adherence to urate-lowering therapy (ULT), predominately allopurinol, from Australia's Pharmaceutical Benefits Scheme (PBS) claims database in association with (1) patient-reported doses and (2) World Health Organization's (WHO) defined daily doses (DDD), namely, allopurinol (400 mg/day) or febuxostat (80 mg/day). METHODS: Proportion of days covered (PDC) was calculated in 108 Gout App (Gout APP) trial participants with at least two recorded ULT dispensings in an approximately 12-month period before provision of intervention or control apps. Adherence was defined as PDC ≥80%. We measured the correlation between the two methods of calculating PDC using a Wilcoxon signed rank test. Agreement between ULT-taking status (self-reports) and ULT-dispensed status (PBS records) was tested with Cohen's kappa (κ), and positive and negative percent agreement. RESULTS: Allopurinol was prescribed in 93.5% of participants taking ULT. Their self-reported mean daily dose (SD) was 291 (167) mg/day. Mean PDC (SD) for allopurinol was 83% (21%) calculated using self-reported dose, and 63% (24%) using WHO's DDD. Sixty-three percent of allopurinol users were identified as adherent (PDC ≥80%) using self-reported dose. There was good agreement between self-reported ULT use and PBS dispensing claims (κ = 0.708, P < .001; positive percent agreement = 90%, negative percent agreement = 82%). CONCLUSIONS: Participant-reported allopurinol daily doses, in addition to PBS dispensing claims, may enhance confidence in estimating PDC and adherence compared to using DDD. This approach improves adherence estimations from pharmaceutical claims datasets for medications where daily doses vary between individuals or where there is a wide therapeutic dose range.

'We are somehow fixated on this being a diabetes drug': a qualitative study exploring the views of cardiologists and nephrologists about sodium-glucose cotransporter 2 inhibitor initiation.

BACKGROUND: Sodium-glucose cotransporter 2 inhibitors (SGLT2i) are now indicated for heart failure and chronic kidney disease (CKD), irrespective of the presence of diabetes. Hence, cardiologists and nephrologists have an important role in initiating these drugs. AIMS: To explore cardiologists' and nephrologists' perspectives regarding initiating SGLT2i and their safety monitoring practices when initiating SGLT2i. METHODS: Purposive and snowball approaches were used to recruit participants working in diverse areas in New South Wales, Australia. Semi-structured interviews were conducted with 12 cardiologists and 12 nephrologists. Interviews were conducted until thematic saturation was reached. Emergent themes were identified from transcripts. An iterative general inductive approach was used for data analysis. RESULTS: There was a reluctance amongst most non-heart-failure subspecialist cardiologists to initiate SGLT2i. Reasons included the perception of SGLT2i as diabetes drugs, concern about side effects, lack of experience and issues with follow-up. In contrast, nephrologists reported feeling confident to initiate SGLT2i. Nephrologists varied in their opinions about the severity of CKD at which SGLT2i initiation was reasonable and monitoring of renal function following initiation. Government subsidisation was an important factor in the decision to prescribe SGLT2i to people without diabetes. CONCLUSIONS: Our findings highlight the complex transition from the perception of SGLT2i as diabetes drugs to cardiometabolic and reno-protective agents. Interdisciplinary collaboration may enable greater confidence amongst specialists to initiate SGLT2i, including in patients with CKD. Additionally, there is a need for clear and detailed guidance about SGLT2i prescription in patients with renal dysfunction and renal function monitoring following SGLT2i initiation.

The Influence of a Therapeutic Drug Monitoring Service on Vancomycin-Associated Nephrotoxicity.

Vancomycin's widespread use as the mainstay antibiotic against methicillin-resistant Staphylococcus aureus infections is complicated by its narrow therapeutic index. Therapeutic drug monitoring using area under the concentration-time curve (AUC)-guided dosing is recommended to optimize therapy and prevent vancomycin-associated nephrotoxicity (VAN). In 2018, a consultative therapeutic drug monitoring Advisory Service (the Service) was piloted at an Australian hospital to enable AUC-guided vancomycin dosing. This study sought to compare the incidence of VAN pre- and post-Service implementation. A 4-year retrospective observational study of intravenous vancomycin therapy (greater than 48 hours) in adults (aged 18 years or older), spanning 3 years before and 1-year after implementation of the Service was undertaken. Nephrotoxicity was defined as an increase in serum creatinine concentrations of 26.5 µmol/L or greater or 50% or more from baseline, on 2 or more consecutive days. Univariate analysis was performed to compare patients before and after implementation, and with and without VAN. Independent factors associated with VAN were identified using a multivariate model. In total, 971 courses of vancomycin therapy, administered to 781 patients, were included: 764 courses (603 patients) before implementation and 207 courses (163 patients) after implementation. The incidence of VAN decreased by 5% after Service implementation (15% before implementation vs 10% after implementation; P = .075). Independent factors associated with VAN were sepsis, heart failure, solid-organ transplant, concomitant piperacillin-tazobactam, and average vancomycin AUC during therapy. In conclusion, there was a nonsignificant trend toward a reduced incidence of VAN after the Service. Larger prospective studies are needed to confirm the efficacy of the Service.

Ongoing challenges of off-label prescribing.

Off-label prescribing refers to prescribing that is not concordant with the indications, doses, routes of administration or patient groups included in the Australian approved product information. Off-label prescribing is common, especially for vulnerable patient groups who tend to be excluded from clinical trials, such as children and pregnant women. There may be increased risk of prescriber liability if the patient experiences an adverse event following off-label prescription, particularly when supporting evidence or guidelines are lacking. There may be additional costs to the patient if the medicine is not subsidised for the off-label indication. Prescribers should ensure patients are aware when a medicine is being prescribed off label, and informed of potential benefits and harms. Alternative pathways for approval of new indications, doses and patient groups may reduce the need for off-label prescribing.

General practitioners' decision-making process to prescribe pain medicines for low back pain: a qualitative study.

BACKGROUND: Pain medicines are widely prescribed by general practitioners (GPs) when managing people with low back pain (LBP), but little is known about what drives decisions to prescribe these medicines. OBJECTIVES: The aim of this study was to investigate what influences GPs' decision to prescribe pain medicines for LBP. DESIGN: Qualitative study with in-depth interviews. SETTING: Australian primary care. PARTICIPANTS: We interviewed 25 GPs practising in Australia experienced in managing LBP (mean (SD) age 53.4 (9.1) years, mean (SD) years of experience: 24.6 (9.3), 36% female). GPs were provided three vignettes describing common LBP presentations (acute exacerbation of chronic LBP, subacute sciatica and chronic LBP) and were asked to think aloud how they would manage the cases described in the vignettes. DATA ANALYSIS: We summarised GP's choices of pain medicines for each vignette using content analysis and used framework analysis to investigate factors that affected GP's decision-making. RESULTS: GPs more commonly prescribed opioid analgesics. Anticonvulsants and antidepressants were also commonly prescribed depending on the presentation described in the vignette. GP participants made decisions about what pain medicines to prescribe for LBP largely based on previous experiences, including their own personal experiences of LBP, rather than guidelines. The choice of pain medicine was influenced by a range of clinical factors, more commonly the patient's pathoanatomical diagnosis. While many adhered to principles of judicious use of pain medicines, polypharmacy scenarios were also common. Concerns about drug-seeking behaviour, adverse effects, stigma around opioid analgesics and pressure from regulators also shaped their decision-making process. CONCLUSIONS: We identified several aspects of decision-making that help explain the current profile of pain medicines prescribed for LBP by GPs. Themes identified by our study could inform future implementation strategies to improve the quality use of medicines for LBP.

Patient factors and health outcomes associated with illness perceptions in people with gout.

OBJECTIVE: Illness perceptions are views and beliefs formed in response to a health threat which may influence self-management behaviours and chronic disease outcomes. Despite effective medication, sub-optimal outcomes in gout are common. This study aimed to quantitatively investigate illness perceptions in gout to examine how illness perceptions relate to health outcomes. METHODS: Data were obtained from a randomised-controlled trial where people with gout (n = 493) completed surveys measuring illness perceptions (Brief Illness Perception Questionnaire (B-IPQ)), gout flares, medication adherence, health-related quality of life, healthcare utilisation and productivity, alongside serum urate blood tests at baseline, 6- and 12-month follow-ups. Multivariable linear regression identified patient factors independently associated with each B-IPQ item score. Logistic and linear regression, adjusted for age and sex, determined whether baseline B-IPQ items could predict current and future health outcomes. RESULTS: Younger individuals and those with severe gout were more likely to experience pessimistic illness perceptions at baseline. Optimistic illness perceptions were associated with lower odds of having at least one flare in the preceding 6 months. Every 1-point increase in B-IPQ treatment control, indicating the optimistic view that gout is treatable, decreased the odds of a recent flare prior to baseline by 33% (OR : 0.67; 95%CI : 0.53,0.85; p< 0.001) and prior to 12-month follow-up by 15% (OR : 0.85; 95%CI : 0.76,0.96; p= 0.01). Pessimistic illness perceptions also predicted poorer medication adherence, health-related quality of life and productivity but not serum urate levels. CONCLUSION: Modifying pessimistic illness perceptions, including, but not limited to, patient education, may promote prudent self-management behaviours and better outcomes in gout. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry; https://www.anzctr.org.au/; ACTRN12616000455460.

Trends in use of sodium-glucose co-transporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) in Australia in the era of increased evidence of their cardiovascular benefits (2014-2022).

PURPOSE: To investigate trends in SGLT2i and GLP-1RA use in Australia in the era of increased evidence of their cardiovascular benefits. METHODS: We used national dispensing claims for a 10% random sample of Australians to estimate the number of prevalent and new users (no dispensing in the prior year) of SGLT2i or GLP-1RA per month from January 2014 to July 2022. We assessed prescriber specialty and prior use of other antidiabetic and cardiovascular medicines as a proxy for evidence of type 2 diabetes (T2D) and cardiovascular conditions, respectively. RESULTS: We found a large increase in the number of prevalent users (216-fold for SGLT2i; 11-fold for GLP-1RA); in July 2022 approximately 250,000 Australians were dispensed SGLT2i and 120,000 GLP-1RA. Most new users of SGLT2i or GLP-1RA had evidence of both T2D and cardiovascular conditions, although from 2022 onwards, approximately one in five new users of SGLT2i did not have T2D. The proportion of new users initiating SGLT2i by cardiologists increased after 2021, reaching 10.0% of initiations in July 2022. Among new users with evidence of cardiovascular conditions, empagliflozin was the most commonly prescribed SGLT2i, while dulaglutide or semaglutide was the most common GLP-1RA. CONCLUSION: SGLT2i and GLP-1RA use is increasing in Australia, particularly in populations with higher cardiovascular risk. The increased use of SGLT2i among people without evidence of T2D suggests that best-evidence medicines are adopted in Australia across specialties, aligning with new evidence and expanding indications.

Opioid analgesia for acute low back pain and neck pain (the OPAL trial): a randomised placebo-controlled trial.

BACKGROUND: Opioid analgesics are commonly used for acute low back pain and neck pain, but supporting efficacy data are scarce. We aimed to investigate the efficacy and safety of a judicious short course of an opioid analgesic for acute low back pain and neck pain. METHODS: OPAL was a triple-blinded, placebo-controlled randomised trial that recruited adults (aged ≥18 years) presenting to one of 157 primary care or emergency department sites in Sydney, NSW, Australia, with 12 weeks or less of low back or neck pain (or both) of at least moderate pain severity. Participants were randomly assigned (1:1) using statistician-generated randomly permuted blocks to guideline-recommended care plus an opioid (oxycodone-naloxone, up to 20 mg oxycodone per day orally) or guideline-recommended care and an identical placebo, for up to 6 weeks. The primary outcome was pain severity at 6 weeks measured with the pain severity subscale of the Brief Pain Inventory (10-point scale), analysed in all eligible participants who provided at least one post-randomisation pain score, by use of a repeated measures linear mixed model. Safety was analysed in all randomly assigned eligible participants. The trial was registered with the Australian New Zealand Clinical Trials Registry (ACTRN12615000775516). FINDINGS: Between Feb 29, 2016, and March 10, 2022, 347 participants were recruited (174 to the opioid group and 173 to the placebo group). 170 (49%) of 346 participants were female and 176 (51%) were male. 33 (19%) of 174 participants in the opioid group and 25 (15%) of 172 in the placebo group had discontinued from the trial by week 6, due to loss to follow-up and participant withdrawals. 151 participants in the opioid group and 159 in the placebo group were included in the primary analysis. Mean pain score at 6 weeks was 2·78 (SE 0·20) in the opioid group versus 2·25 (0·19) in the placebo group (adjusted mean difference 0·53, 95% CI -0·00 to 1·07, p=0·051). 61 (35%) of 174 participants in the opioid group reported at least one adverse event versus 51 (30%) of 172 in the placebo group (p=0·30), but more people in the opioid group reported opioid-related adverse events (eg, 13 [7·5%] of 174 participants in the opioid group reported constipation vs six [3·5%] of 173 in the placebo group). INTERPRETATION: Opioids should not be recommended for acute non-specific low back pain or neck pain given that we found no significant difference in pain severity compared with placebo. This finding calls for a change in the frequent use of opioids for these conditions. FUNDING: National Health and Medical Research Council, University of Sydney Faculty of Medicine and Health, and SafeWork SA.

Optimizing the dosing of vancomycin in patients receiving intermittent haemodialysis with low-flux filters, and the potential impact of dosing software.

AIM: Iterative approaches to vancomycin dosing (e.g., dosing when trough concentrations <15-20 mg/L) can be inadequate. Computer-guided dosing may be superior but has not been evaluated in patients with kidney failure receiving replacement therapy. We evaluated vancomycin concentrations using a hospital protocol and a pharmacokinetic software. We measured vancomycin clearance by the FX8 low-flux filter because data are absent. METHODS: We retrospectively reviewed records of adults with kidney failure requiring replacement therapy receiving vancomycin and dialysed with the FX8 low-flux filter, and calculated the proportion of pre-dialysis concentrations that were within, above or below a specified range. One and two-compartment models in the pharmacokinetic software were assessed by computing mean prediction error (MPE) and root mean square error (RMSE) of observed versus predicted concentrations. Vancomycin extracorporeal clearance was prospectively determined using the extraction method. RESULTS: In 24 patients (34 courses; 139 paired observed and predicted concentrations), 62/139 (45%) pre-dialysis concentrations were 15-25 mg/L, 29/139 (21%) were above, and 48/139 (35%) were below. MPE for the one-compartment model was -0.2 mg/L, RMSE 5.3 mg/L. MPE for the two-compartment model was 2.0 mg/L, RMSE 5.6 mg/L. Excluding the first paired concentrations, the subsequent MPE (n = 105) using one-compartment model was -0.5 mg/L, RMSE 5.6 mg/L. The MPE for the two-compartment model was 2.1 mg/L, RMSE 5.8 mg/L. The median extracorporeal clearance was 70.7 mL/min (range: 10.3-130.3; n = 22). CONCLUSIONS: Vancomycin dosing was suboptimal and the pharmacokinetic software was not sufficiently predictive. These may improve with a loading dose. The substantial removal of vancomycin by low-flux filters is not accounted for by the models tested.