Imputing missing patient-level data and propensity score matching in cost-effectiveness analysis in Crohn's disease.

OBJECTIVES: The effect of imputing missing data followed by propensity score analysis on the incremental cost-effectiveness ratio (ICER) in a cost-effectiveness analysis is unknown. The objective was to compare alternative approaches in grouping data following imputation and prior to calculating propensity scores for use in economic evaluation. METHODS: Patient-level data from an observational study of 573 children with Crohn's disease were used in a microsimulation model to determine the incremental cost of early anti-tumor necrosis factor-α treatment compared to standard care per remission week gained. Multiple imputation of a missing covariate followed by propensity score matching to create comparator groups was approached in two ways. The Within approach calculated propensity scores on each imputed dataset separately, while the Across method averaged propensity scores to create one matched population resulting in multiple sets of health state transition probabilities. RESULTS: The incremental cost per remission week gained ranged from CAD$2,236 to CAD$12,464 (mean CAD$4,266) with Within datasets and was CAD$4,679 per remission week gained with the Across dataset. CONCLUSION: Imputation of missing patient-level data and propensity score analysis increases methodological uncertainty in cost-effectiveness analysis. The present study indicated that the Across approach may be less cumbersome, and slightly reduce bias and variance.

Population pharmacokinetics of vancomycin in paediatric patients with febrile neutropenia and augmented renal clearance: development of new dosing recommendations.

OBJECTIVES: The purpose of this study was to evaluate the influence of augmented renal clearance (ARC) on vancomycin clearance and provide dosage recommendations for paediatric patients with febrile neutropenia following HSCT. METHODS: A population pharmacokinetic analysis was performed based on a two-compartment model structure using a non-linear mixed-effect modelling approach. Monte Carlo simulations were conducted as a target attainment analysis of AUC between 400 mg·h/L and 650 mg·h/L for MRSA at an MIC of 1 mg/L. RESULTS: A total of 165 paediatric patients and 276 vancomycin serum concentrations were analysed in this study. Age, body weight, estimated glomerular filtration rate (eGFR) and fever (≥38.0°C) were identified as factors that significantly influenced vancomycin clearance. The median eGFR of the population was 143 mL/min/1.73 m2 and 34% of patients showed an eGFR ≥160 mL/min/1.73 m2, which may be classified as ARC. Our simulations showed that current dosing recommendations result in poor target attainment. In particular, children aged 6 months old to 6 years old with ARC require an initial vancomycin dose up to 35%-65% higher than the current dosing guidelines. CONCLUSIONS: ARC is frequently observed in paediatric patients with post-HSCT febrile neutropenia, resulting in a significant increase in vancomycin clearance. We propose a vancomycin dosing strategy for children with febrile neutropenia following HSCT based on eGFR, age, weight and body temperature.

Assessment of the Implementation of Pharmacogenomic Testing in a Pediatric Tertiary Care Setting.

Importance: Pharmacogenomic (PGx) testing provides preemptive pharmacotherapeutic guidance regarding the lack of therapeutic benefit or adverse drug reactions of PGx targeted drugs. Pharmacogenomic information is of particular value among children with complex medical conditions who receive multiple medications and are at higher risk of developing adverse drug reactions. Objectives: To assess the implementation outcomes of a PGx testing program comprising both a point-of-care model that examined targeted drugs and a preemptive model informed by whole-genome sequencing that evaluated a broad range of drugs for potential therapy among children in a pediatric tertiary care setting. Design, Setting, and Participants: This cohort study was conducted at The Hospital for Sick Children in Toronto, Ontario, from January 2017 to September 2020. Pharmacogenomic analyses were performed among 172 children who were categorized into 2 groups: a point-of-care cohort and a preemptive cohort. The point-of-care cohort comprised 57 patients referred to the consultation clinic for planned therapy with PGx targeted drugs and/or for adverse drug reactions, including lack of therapeutic benefit, after the receipt of current or past medications. The preemptive cohort comprised 115 patients who received exploratory whole-genome sequencing-guided PGx testing for their heart conditions from the cardiac genome clinic at the Ted Rogers Centre for Heart Research. Exposures: Patients received PGx analysis of whole-genome sequencing data and/or multiplex genotyping of 6 pharmacogenes (CYP2C19, CYP2C9, CYP2D6, CYP3A5, VKORC1, and TPMT) that have established PGx clinical guidelines. Main Outcomes and Measures: The number of patients for whom PGx test results warranted deviation from standard dosing regimens. Results: A total of 172 children (mean [SD] age, 8.5 [5.6] years; 108 boys [62.8%]) were enrolled in the study. In the point-of-care cohort, a median of 2 target genes (range, 1-5 genes) were investigated per individual, with CYP2C19 being the most frequently examined; genotypes in 21 of 57 children (36.8%) were incompatible with standard treatment regimens. As expected from population allelic frequencies, among the 115 children in the whole-genome sequencing-guided preemptive cohort, 92 children (80.0%) were recommended to receive nonstandard treatment regimens for potential drug therapies based on their 6-gene pharmacogenetic profile. Conclusions and Relevance: In this cohort study, among both the point-of-care and preemptive cohorts, the multiplex PGx testing program provided dosing recommendations that deviated from standard regimens at an overall rate that was similar to the population frequencies of relevant variants.

Cost-effectiveness and Clinical Outcomes of Early Anti-Tumor Necrosis Factor-α Intervention in Pediatric Crohn's Disease.

BACKGROUND: Anti-tumor necrosis factor-α (anti-TNF-α) treatments are increasingly used to treat pediatric Crohn's disease, even without a prior trial of immunomodulators, but the cost-effectiveness of such treatment algorithms has not been formally examined. Drug plan decision-makers require evidence of cost-effectiveness to inform funding decisions. The objective was to assess the incremental cost-effectiveness of early intervention with anti-TNF-α treatment vs a conventional step-up strategy per steroid-free remission-week gained from public health care and societal payer perspectives over 3 years. METHODS: A probabilistic microsimulation model was constructed for children with newly diagnosed moderate to severe Crohn's disease receiving anti-TNF-α treatment and concomitant treatments within the first 3 months of diagnosis compared with children receiving standard care consisting of steroids and/or immunomodulators with the possibility of anti-TNF-α treatment after 3 months of diagnosis. A North American multicenter observational study with 360 patients provided input into clinical outcomes and health care resource use. RESULTS: Early intervention with anti-TNF-α treatment was more costly, with an incremental cost of CAD$31,112 (95% confidence interval [CI], $2939-$91,715), and more effective, with 11.3 more weeks in steroid-free remission (95% CI, 10.6-11.6) compared with standard care, resulting in an incremental cost per steroid-free remission-week gained of CAD$2756 from an Ontario public health care perspective and CAD$2968 from a societal perspective. The incremental cost-effectiveness ratio was sensitive to the price of infliximab. CONCLUSIONS: The results suggest that although early anti-TNF-α was not cost-effective, it was clinically beneficial. These findings, along with other randomized controlled trial evidence, may inform formulary decision-making.

The Future of Precision Medicine.

Precision medicine is an emerging framework to maximize therapeutic benefit by modifying the treatment for individual patients based on their variations in demographic, genomic, and environmental factors. In particular, "Pharmacogenomics" and "Therapeutic Drug Monitoring" are key elements of individualized drug treatment, staging Clinical Pharmacology at the forefront of precision medicine.

Care and cost consequences of pediatric whole genome sequencing compared to chromosome microarray.

The clinical use of whole-genome sequencing (WGS) is expected to alter pediatric medical management. The study aimed to describe the type and cost of healthcare activities following pediatric WGS compared to chromosome microarray (CMA). Healthcare activities prompted by WGS and CMA were ascertained for 101 children with developmental delay over 1 year. Activities following receipt of non-diagnostic CMA were compared to WGS diagnostic and non-diagnostic results. Activities were costed in 2016 Canadian dollars (CDN). Ongoing care accounted for 88.6% of post-test activities. The mean number of lab tests was greater following CMA than WGS (0.55 vs. 0.09; p = 0.007). The mean number of specialist visits was greater following WGS than CMA (0.41 vs. 0; p = 0.016). WGS results (diagnostic vs. non-diagnostic) modified the effect of test type on mean number of activities (p < 0.001). The cost of activities prompted by diagnostic WGS exceeded $557CDN for 10% of cases. In complex pediatric care, CMA prompted additional diagnostic investigations while WGS prompted tailored care guided by genotypic variants. Costs for prompted activities were low for the majority and constitute a small proportion of total test costs. Optimal use of WGS depends on robust evaluation of downstream care and cost consequences.

Pediatric resident education and needs assessment in clinical pharmacology.

OBJECTIVE: To identify perceived and unperceived educational needs of residents to organize a seminar series in clinical pharmacology. METHOD: All pediatric residents (48) and all attending general pediatric staff (20) were sent structured questionnaires with potential seminar topics. Data from previous pharmacy chart audits and complaints lodged with patient care representatives were analyzed as the environmental scans. RESULTS: There was a 75% response rate from both residents and staff. The responses were very similar and the only significant difference was the response to a seminar on correcting electrolyte imbalances which the residents favoured (p = 0.005). The environmental scans identified pain management as one of the main areas needing improvement. CONCLUSION: Perceived learning needs of residents are similar but not identical to those identified by the faculty. Environmental scanning can be used to identify unperceived learning needs.