Indirect treatment comparison and economic evaluation of novel oral anticoagulants for the prevention of stroke in patients with atrial fibrillation in the Netherlands

Objectives: Management with vitamin K antagonists (VKAs) has been an effective and cost-effective strategy for stroke prevention in atrial fibrillation (AF) but is associated with shortcomings. Novel oral anticoagulants (NOACs) were developed with the aims of no monitoring requirement and improved effectiveness and safety profiles. Economic evaluations require the comparison of all relevant options. However, there are no randomized controlled trials (RCTs) directly comparing these agents. In such cases, indirect treatment comparison (ITC) can be used to synthesize indirect comparative evidence. Through ITC-based evidence synthesis the cost-effectiveness of all available NOACs for stroke prevention in AF patients may be evaluated. Methods: ITC models were based on RCTs data comparing dabigratran, rivaroxaban, or apixaban with VKA treatment. Relative effectiveness was estimated for stroke/systemic embolism, intracranial hemorrhage, myocardial infarction, extracranial hemorrhage, and minor bleeding. A Markov model was developed using ITC-synthesized evidence with VKA as the baseline. Health utilities were collected from international sources whereas costs and mortality data were extracted from Dutch sources. Univariate and probabilistic sensitivity analyses (PSA) were conducted on the base-case incremental cost-effectiveness ratio (ICER). Results: The ICERs for dabigatran, apixaban, and rivaroxaban compared to VKA were € 12,146/QALY, € 12,488/QALY, and € 24,124/QALY, respectively. Sensitivity analysis using the upper and lower limits of the 95% confidence interval for absolute stroke risk with VKA treatment resulted in ICERs that varied drastically from dominance for VKA to being dominated by all NOACs. This is likely due to the large uncertainty observed between the baseline risk profiles of the VKA arms in the three RCTs. The options with the highest probabilities of cost-effectiveness in PSA were VKA at thresholds under € 13,000/QALY and dabigatran or apixaban at thresholds above this mark. Conclusions: Dabigatran and apixaban were shown to be cost-effective options for AF patients in The Netherlands. However, these results were strongly influenced by uncertainty around stroke risk with VKA treatment

Analyzing generic and branded substitution patterns in the Netherlands using prescription data

BACKGROUND: As in other societies, pharmaceutical expenditures in the Netherlands are rising every year. As a consequence, needs for cost control are often expressed. One possible solution for cost control could come through increasing generic substitution by pharmacists. We aim to analyse the extent and nature of substitution in recent years and estimate the likelihood of generic or branded substitution in Dutch pharmacies in relation to various characteristics. METHODS: We utilized a linked prescription dataset originating from a general practitioner (GP) and a pharmacy database, both from the northern Netherlands. We selected specific drugs of interest, containing about 55,000 prescriptions from 15 different classes. We used a crossed generalized linear mixed model to estimate the effects that certain patient and pharmacy characteristics as well as timing have on the likelihood that a prescription will eventually be substituted by the pharmacist. RESULTS: Generic substitution occurred at 25% of the branded prescriptions. Generic substitution was more likely to occur earlier in time after patent expiry and to patients that were older and more experienced in their drug use. Individually owned pharmacies had a lower probability of generic substitution compared to chain pharmacies. Oppositely, branded substitution occurred in 10% of generic prescriptions and was positively related to the patients' experience in branded use. Individually owned pharmacies were more likely to substitute a generic drug to a branded compared to other pharmacies. Antidepressant and PPI prescriptions were less prone to generic and more prone to branded substitution. CONCLUSION: Analysis of prescription substitution by the pharmacist revealed strong relations between substitution and patient experience on drug use, pharmacy status and timing. These findings can be utilised to design further strategies to enhance generic substitution

A Bayesian response-adaptive dose-finding and comparative effectiveness trial

Background/Aims: Combinations of treatments that have already received regulatory approval can offer additional benefit over Each of the treatments individually. However, trials of these combinations are lower priority than those that develop novel therapies, which can restrict funding, timelines and patient availability. This article develops a novel trial design to facilitate the evaluation of New combination therapies. This trial design combines elements of phase II and phase III trials to reduce the burden of evaluating combination therapies, while also maintaining a feasible sample size. This design was developed for a randomised trial that compares the properties of three combination doses of ketamine and dexmedetomidine, given intranasally, to ketamine delivered intravenously for children undergoing a closed reduction for a fracture or dislocation. Methods: This trial design uses response-adaptive randomisation to evaluate different dose combinations and increase the information collected for successful novel drug combinations. The design then uses Bayesian dose-response modelling to undertake a comparative effectiveness analysis for the most successful dose combination against a relevant comparator. We used simulation methods determine the thresholds for adapting the trial and making conclusions. We also used simulations to evaluate the probability of selecting the dose combination with the highest true effectiveness the operating characteristics of the design and its Bayesian predictive power. Results: With 410 participants, five interim updates of the randomisation ratio and a probability of effectiveness of 0.93, 0.88 and 0.83 for the three dose combinations, we have an 83% chance of randomising the largest number of patients to the drug with the highest probability of effectiveness. Based on this adaptive randomisation procedure, the comparative effectiveness analysis has a type I error of less than 5% and a 93% chance of correcting concluding non-inferiority, when the probability of effectiveness for the optimal combination therapy is 0.9. In this case, the trial has a greater than 77% chance of meeting its dual aims of dose-finding and comparative effectiveness. Finally, the Bayesian predictive power of the trial is over 90%. Conclusions: By simultaneously determining the optimal dose and collecting data on the relative effectiveness of an intervention, we can minimise administrative burden and recruitment time for a trial. This will minimise the time required to get effective, safe combination therapies to patients quickly. The proposed trial has high potential to meet the dual study objectives within a feasible overall sample size

Determining a Bayesian predictive power stopping rule for futility in a non-inferiority trial with binary outcomes.

Background/Aims: Non-inferiority trials investigate whether a novel intervention, which typically has other benefits (i.e., cheaper or safer), has similar clinical effectiveness to currently available treatments. In situations where interim evidence in a non-inferiority trial suggests that the novel treatment is truly inferior, ethical concerns with continuing randomisation to the inferior intervention are raised. Thus, if interim data indicate that concluding non-inferiority at the end of the trial is unlikely, stopping for futility should be considered. To date, limited examples are available to guide the development of stopping rules for non-inferiority trials. Methods: We used a Bayesian predictive power approach to develop a stopping rule for futility for a trial collecting binary outcomes. We evaluated the frequentist operating characteristics of the stopping rule to ensure control of the Type I and Type II error. Our case study is the Intranasal Ketamine for Procedural Sedation trial (INK trial), a non-inferiority trial designed to assess the sedative properties of ketamine administered using two alternative routes. Results: We considered implementing our stopping rule after the INK trial enrols 140 patients out of 560. The trial would be stopped if 12 more patients experience a failure on the novel treatment compared to standard care. This trial has a type I error rate of 2.2% and a power of 80%. Conclusions: Stopping for futility in non-inferiority trials reduces exposure to ineffective treatments and preserves resources for alternative research questions. Futility stopping rules based on Bayesian predictive power are easy to implement and align with trial aims. Trial registration: ClinicalTrials.gov NCT02828566 July 11, 2016

Non-steroidal or opioid analgesia use for children with musculoskeletal injuries (the No OUCH study): statistical analysis plan.

BACKGROUND: Pediatric musculoskeletal injuries cause moderate to severe pain, which should ideally be addressed upon arrival to the emergency department (ED). Despite extensive research in ED-based pediatric pain treatment, recent studies confirm that pain management in this setting remains suboptimal. The No OUCH study consist of two complementary, randomized, placebo-controlled trials that will run simultaneously for patients presenting to the ED with an acute limb injury and a self-reported pain score of at least 5/10, measured via a verbal numerical rating scale (vNRS). Caregiver/parent choice will determine whether patients are randomized to the two-arm or three-arm trial. In the two-arm trial, patients will be randomized to receive either ibuprofen alone or ibuprofen in combination with acetaminophen. In the three-arm trial, patients can also be randomized to a third arm where they would receive ibuprofen in combination with hydromorphone. This article details the statistical analysis plan for the No OUCH study and was submitted before the trial outcomes were available for analysis. METHODS/DESIGN: The primary endpoint of the No OUCH study is self-reported pain at 60 min, recorded using a vNRS. The principal safety outcome is the presence of any adverse event related to study drug administration. Secondary effectiveness endpoints include pain measurements using the Faces Pain Scale-Revised and the visual analog scale, time to effective analgesia, requirement of a rescue analgesic, missed fractures, and observed pain reduction using different definitions of successful analgesia. Secondary safety outcomes include sedation measured using the Ramsay Sedation Score and serious adverse events. Finally, the No OUCH study investigates the reasons given by the caregiver for selecting the two-arm (Non-Opioid) or three-arm (Opioid) trial, caregiver satisfaction, physician preferences for analgesics, and caregiver comfort with at-home pain management. DISCUSSION: The No OUCH study will inform the relative effectiveness of acetaminophen and hydromorphone, in combination with ibuprofen, and ibuprofen alone as analgesic agents for patients presenting to the ED with an acute musculoskeletal injury. The data from these trials will be analyzed in accordance with this statistical analysis plan. This will reduce the risk of producing data-driven results and bias in our reported outcomes. TRIAL REGISTRATION: ClinicalTrials.gov NCT03767933 . Registered on December 7, 2018