Optimising trial designs to identify appropriate antibiotic treatment durations

Optimising antibiotic exposure by customising the duration of treatment for respiratory tract infections based on patient needs in primary care

Primary care antimicrobial stewardship programs have limited success in reducing antibiotic use, prompting the search for new strategies. Convincing general practitioners to resist antibiotic prescription amid uncertainty or patient demands usually poses a significant challenge. Despite common practice, standard durations for common infections lack support from clinical studies. Contrary to common belief, extending antibiotic treatment beyond the resolution of symptoms does not seem to prevent or reduce antimicrobial resistance. Shortening the duration of antibiotic therapy has shown to be effective in mitigating the spread of resistance, particularly in cases of pneumonia. Recent hospital randomised trials suggest that ending antibiotic courses by day three for most lower respiratory tract infections is effective and safe. While community studies are scarce, it is likely that these shorter, tailored courses to meet patients' needs would also be effective and safe in primary care. Therefore, primary care studies should investigate the outcomes of advising patients to discontinue antibiotic treatment upon symptom resolution. Implementing patient-centred, customised treatment durations, rather than fixed courses, is crucial for meeting individual patient needs.

A comparison of clinical development pathways to advance tuberculosis regimen development

BACKGROUND

Current tuberculosis (TB) regimen development pathways are slow and in urgent need of innovation. We investigated novel phase IIc and seamless phase II/III trials utilizing multi-arm multi-stage and Bayesian response adaptive randomization trial designs to select promising combination regimens in a platform adaptive trial.

METHODS

Clinical trial simulation tools were built using predictive and validated parametric survival models of time to culture conversion (intermediate endpoint) and time to TB-related unfavorable outcome (final endpoint). This integrative clinical trial simulation tool was used to explore and optimize design parameters for aforementioned trial designs.

RESULTS

Both multi-arm multi-stage and Bayesian response adaptive randomization designs were able to reliably graduate desirable regimens in ≥ 95% of trial simulations and reliably stop suboptimal regimens in ≥ 90% of trial simulations. Overall, adaptive phase IIc designs reduced patient enrollment by 17% and 25% with multi-arm multi-stage and Bayesian response adaptive randomization designs respectively compared to the conventional sequential approach, while seamless designs reduced study duration by 2.6 and 3.5 years respectively (typically ≥ 8.5 years for standard sequential approach).

CONCLUSIONS

In this study, we demonstrate that adaptive trial designs are suitable for TB regimen development, and we provide plausible design parameters for a platform adaptive trial. Ultimately trial design and specification of design parameters will depend on clinical trial objectives. To support decision-making for clinical trial designs in contemporary TB regimen development, we provide a flexible clinical trial simulation tool that can be used to explore and optimize design features and parameters.

CE: Pediatric Antibiotic Stewardship

ABSTRACT

With the rise of antibiotic resistance, antimicrobial stewardship programs can now be found in the ambulatory setting, where nearly 95% of antibiotic prescriptions originate. Judicious use of antibiotics is of particular importance to the ambulatory pediatric provider, as the annual antibiotic prescription rate is highest among children ages two and younger and inappropriate early-life antibiotic use is associated with elevated childhood risk of several medical conditions. While most ambulatory antibiotic stewardship programs have focused on shaping clinician behaviors to prevent unnecessary antibiotic prescribing, duration of antibiotic therapy has been found to be a critical, yet underexamined, facet of antibiotic use. In the past, duration of antibiotic therapy was largely based on convention and expert opinion, with little scientific evidence supporting many of the recommendations. Research suggests that many common pediatric infections such as acute otitis media, community-acquired pneumonia, streptococcal pharyngitis, and urinary tract infections can be effectively and safely treated with reduced courses of antibiotic therapy. In addition to reducing the incidence of antibiotic resistance, a shorter duration of antibiotic therapy may help prevent many adverse effects associated with antibiotic treatment. Current studies on the duration of antibiotic therapy, especially in pediatrics, are limited as they often rely on data extrapolated from adult studies that fail to consider the effects of age-related growth and development on both pharmacokinetics and pharmacodynamics. Future investigation into this topic is also limited by researchers' reliance on subsidies from pharmaceutical companies; clinicians' fear of undertreating infection; and hesitancy to deviate from current standards of care, even when such standards are not evidence based. Despite these challenges, the dangers of inappropriate antibiotic use in the pediatric population warrant further evaluation.

Prospective trial of different antimicrobial treatment durations for presumptive canine urinary tract infections

Background

Avoidance of unnecessary antimicrobial administration is a key tenet of antimicrobial stewardship; knowing the optimal duration of therapy obviates over-treatment. However, little research has been performed to establish course lengths for common canine infections. In clinical practice, antimicrobial therapy is frequently prescribed in dogs presenting lower urinary tract signs (haematuria, pollakiuria and dysuria/stranguria). The proposed length of treatment in International Consensus guidelines has decreased with each iteration, but these recommendations remain arbitrary and largely extrapolated from experience in people.

Methods

The objective of this prospective, multi-centre study is to find the shortest course duration that is non-inferior to the standard duration of 7 days of amoxicillin/clavulanate in terms of clinical outcomes for female dogs with lower urinary tract signs consistent with a urinary tract infection. An electronic data capture platform will be used by participating veterinarians working in clinical practice in the United Kingdom. Eligible dogs must be female, aged between 6 months and 10 years and have lower urinary tract signs of up to seven days’ duration. Enrolment will be offered in cases where the case clinician intends to prescribe antimicrobial therapy. Automatic pseudo-randomisation to treatment group will be based on the day of presentation (Monday-Friday); all antimicrobial courses will be completed on the Sunday after presentation generating different treatment durations. Follow-up data will be collected 1, 8 and 22–26 days after completion of the antimicrobial course to ensure effective safety netting, and to monitor short-term outcome and recurrence rates. Informed owner consent will be obtained in all cases. The study is approved by the Ethical Review Board of the University of Nottingham and has an Animal Test Certificate from the Veterinary Medicine’s Directorate.

Discussion

This study has been designed to mirror current standards of clinical management; conclusions should therefore, be widely applicable and guide practising veterinarians in their antimicrobial decision-making process. A duration-response curve will be created allowing determination of the optimal treatment duration for the management of female dogs with lower urinary tract signs. It is hoped that these results will contribute valuable information to improve future antimicrobial stewardship as part of a wider one-health perspective.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02974-y.

Antibiotic treatment of common infections: more evidence to support shorter durations

PURPOSE OF REVIEW

Although there is increasing recognition of the link between antibiotic overuse and antimicrobial resistance, clinician prescribing is often unnecessarily long and motivated by fear of clinical relapse. High-quality evidence supporting shorter treatment durations is needed to give clinicians confidence to change prescribing habits. Here we summarize recent randomized controlled trials investigating antibiotic short courses for common infections in adult patients.

RECENT FINDINGS

Randomized trials in the last five years have demonstrated noninferiority of short-course therapy for a range of conditions including community acquired pneumonia, intraabdominal sepsis, gram-negative bacteraemia and vertebral osteomyelitis.

SUMMARY

Treatment durations for many common infections have been based on expert opinion rather than randomized trials. There is now evidence to support shorter courses of antibiotic therapy for many conditions.

Knowledge, attitudes and influencers of North American dog-owners surrounding antimicrobials and antimicrobial stewardship

OBJECTIVES

To quantify the individual influences of antimicrobial cost, method of administration and drug importance in human medicine on dog-owner antimicrobial preference, and determine knowledge, attitudes and influencers of dog-owners surrounding antimicrobials and antimicrobial stewardship.

MATERIALS AND METHODS

Data were collected through an online survey targeting three dog-owner participant groups. These consisted of individuals residing in: (1) Canada, (2) USA and (3) any country recruited through an educational social media site. USA and Canadian participants were financially compensated. Conjoint analysis was used to quantify the influence of antimicrobial cost, method of administration and drug importance in human medicine. Descriptive and analytical statistics were used for data evaluation.

RESULTS

A total of 809 surveys were completed. Antimicrobial cost accounted for 47% of dog-owner preferences, followed by method of administration (31%) and drug importance in human medicine (22%). All groups preferred lower cost drugs that were administered once by injection. Participants were more likely to prefer drugs considered "very important" in human medicine, except for the social media participants, who preferred drugs that were "not at all important." Most respondents (86%) reported antimicrobial resistance as important in human medicine and 29% believed antimicrobial use in pets posed a risk for antimicrobial resistance in humans. Participants recruited through social media, and those in the highest education category, were significantly more likely to report antimicrobial use in pets as a risk to people.

CLINICAL SIGNIFICANCE

Cost was the most important factor in dog-owner antimicrobial preferences. There is a need for dog-owner antimicrobial stewardship education.

The DURATIONS randomised trial design: Estimation targets, analysis methods and operating characteristics

Background:

Designing trials to reduce treatment duration is important in several therapeutic areas, including tuberculosis and bacterial infections. We recently proposed a new randomised trial design to overcome some of the limitations of standard two-arm non-inferiority trials. This DURATIONS design involves randomising patients to a number of duration arms and modelling the so-called ‘duration-response curve’. This article investigates the operating characteristics (type-1 and type-2 errors) of different statistical methods of drawing inference from the estimated curve.

Methods:

Our first estimation target is the shortest duration non-inferior to the control (maximum) duration within a specific risk difference margin. We compare different methods of estimating this quantity, including using model confidence bands, the delta method and bootstrap. We then explore the generalisability of results to estimation targets which focus on absolute event rates, risk ratio and gradient of the curve.

Results:

We show through simulations that, in most scenarios and for most of the estimation targets, using the bootstrap to estimate variability around the target duration leads to good results for DURATIONS design-appropriate quantities analogous to power and type-1 error. Using model confidence bands is not recommended, while the delta method leads to inflated type-1 error in some scenarios, particularly when the optimal duration is very close to one of the randomised durations.

Conclusions:

Using the bootstrap to estimate the optimal duration in a DURATIONS design has good operating characteristics in a wide range of scenarios and can be used with confidence by researchers wishing to design a DURATIONS trial to reduce treatment duration. Uncertainty around several different targets can be estimated with this bootstrap approach.

Optimising efficacy of antibiotics against systemic infection by varying dosage quantities and times

Mass production and use of antibiotics has led to the rise of resistant bacteria, a problem possibly exacerbated by inappropriate and non-optimal application. Antibiotic treatment often follows fixed-dose regimens, with a standard dose of antibiotic administered equally spaced in time. But are such fixed-dose regimens optimal or can alternative regimens be designed to increase efficacy? Yet, few mathematical models have aimed to identify optimal treatments based on biological data of infections inside a living host. In addition, assumptions to make the mathematical models analytically tractable limit the search space of possible treatment regimens (e.g. to fixed-dose treatments). Here, we aimed to address these limitations by using experiments in a Galleria mellonella (insect) model of bacterial infection to create a fully parametrised mathematical model of a systemic Vibrio infection. We successfully validated this model with biological experiments, including treatments unseen by the mathematical model. Then, by applying artificial intelligence, this model was used to determine optimal antibiotic dosage regimens to treat the host to maximise survival while minimising total antibiotic used. As expected, host survival increased as total quantity of antibiotic applied during the course of treatment increased. However, many of the optimal regimens tended to follow a large initial ‘loading’ dose followed by doses of incremental reductions in antibiotic quantity (dose ‘tapering’). Moreover, application of the entire antibiotic in a single dose at the start of treatment was never optimal, except when the total quantity of antibiotic was very low. Importantly, the range of optimal regimens identified was broad enough to allow the antibiotic prescriber to choose a regimen based on additional criteria or preferences. Our findings demonstrate the utility of an insect host to model antibiotic therapies in vivo and the approach lays a foundation for future regimen optimisation for patient and societal benefits.

Research into optimal antibiotic use to improve efficacy is far behind that of cancer care, where personalised treatment is common. The integration of mathematical models with biological observations offers hope to optimise antibiotic use, and in this present study an in vivo insect model of systemic Vibrio infection was used for the first time to determine critical model parameters for optimal antibiotic treatment. By this approach, the optimal regimens tended to result from a large initial ‘loading’ dose followed by subsequent doses of incremental reductions in antibiotic quantity (dose ‘tapering’). The approach and findings of this study opens a new avenue towards optimal application of our precious antibiotic arsenal and may lead to more effective treatment regimens for patients, thus reducing the health and economic burdens associated with bacterial infections. Importantly, it can be argued that until we understand how to use a single antibiotic optimally, it is unlikely we will identify optimal ways to use multiple antibiotics simultaneously.