Time toxicity associated with early phase clinical trial participation

BACKGROUND

Early phase cancer clinical trials (EPCTs) involve experimental drugs being used for the first time in humans. These studies are designed for dose determination and safety, and represent the most time intensive of all clinical trials for both clinicians and patients. We sought to quantify the amount of patient time consumed through EPCT participation.

PATIENTS AND METHODS

A retrospective audit of patients treated in the EPCT unit at Liverpool Hospital, Sydney was carried out from 2013 to 2023. We defined 'time toxicity' (TT) as a composite measure where time-toxic days were considered days with any health care system contact, including clinic visits, infusions, procedures or blood work.

RESULTS

A total of 219 patients across 36 EPCTs were included. The median age was 65 years (range 31-81 years). Patients spent a median of 29% (range 4%-100%) of their days in direct contact with the health care system during their study. Protocol-specified visits accounted for the greatest contribution to total TT in 101 (46%) patients. In 7% (n = 16) of patients, unscheduled visits due to either adverse events or cancer-related symptoms accounted for the greatest TT. TT reduced as patients completed additional cycles of treatment. Patients who completed >10 cycles spent 14% of their days interacting with health care systems compared with 35% for those who completed ≤2 cycles. No statistically significant difference in TT was noted between dose-expansion and dose-escalation studies or trials focusing on immune-oncology versus targeted therapy.

CONCLUSIONS

Our study is the first to report TT in EPCTs with an extended follow-up. Clinicians should be aware of TT when discussing risks and benefits. TT also may not be the appropriate term when describing the time patients invest during EPCTs. Toxicity implies a negative impact, but for many patients, trial participation would be seen as positive. There should be efforts to streamline health care visits to limit TT in EPCTs.

Safe use of antithrombotics for stroke prevention in atrial fibrillation: consideration of risk assessment tools to support decision-making

Clinical guidelines advocate stroke prevention therapy in atrial fibrillation (AF) patients, specifically anticoagulation. However, the decision to initiate treatment is based on the risk (bleeding) versus benefit (prevention of stroke) of therapy, which is often difficult to assess. This review identifies available risk assessment tools to facilitate the safe and optimal use of antithrombotic therapy for stroke prevention in AF. Using key databases and online clinical resources to search the literature (1992-2012), 19 tools have been identified and published to date: 11 addressing stroke risk, 7 addressing bleeding risk and 1 integrating both risk assessments. The stroke risk assessment tools (e.g. CHADS2, CHA2DS2-VASc) share common risk factors: age, hypertension, previous cerebrovascular attack. The bleeding risk assessment tools (e.g. HEMORR2HAGES, HAS-BLED) share common risk factors: age, previous bleeding, renal and liver impairment. In terms of their development, six of the stroke risk assessment tools have been derived from clinical studies, whilst five are based on refinement of existing tools or expert consensus. Many have been evaluated by prospective application to data from real patient cohorts. Bleeding risk assessment tools have been derived from trials, or generated from patient data and then validated via further studies. One identified tool (i.e. Computerised Antithrombotic Risk Assessment Tool [CARAT]) integrates both stroke and bleeding, and specifically considers other key factors in decision-making regarding antithrombotic therapy, particularly those increasing the risk of medication misadventure with treatment (e.g. function, drug interactions, medication adherence). This highlights that whilst separate tools are available to assess stroke and bleeding risk, they do not estimate the relative risk versus benefit of treatment in an individual patient nor consider key medication safety aspects. More effort is needed to synthesize these separate risk assessments and integrate key medication safety issues, particularly since the introduction of new anticoagulants into practice.

Personalized estimates of breast cancer risk in clinical practice and public health

This paper defines absolute risk and some of its properties, and presents applications in breast cancer counseling and prevention. For counseling, estimates of absolute risk give useful perspective and can be used in management decisions that require weighing risks and benefits, such as whether or not to take tamoxifen to prevent breast cancer. Absolute risk models are also useful in designing intervention trials to prevent breast cancer and in assessing the potential reductions in absolute risk of disease that might result from reducing exposures that are associated with breast cancer. In these applications, it is important that the risk model be well calibrated, namely that it accurately predicts the numbers of women who will develop breast cancer in various subsets of the population. Absolute risk models are also needed to implement a 'high risk' prevention strategy that identifies a high-risk subset of the population and focuses intervention efforts on that subset. The limitations of the high-risk strategy are discussed, including the need for risk models with high discriminatory accuracy, and the need for less toxic interventions that can reduce the threshold of risk above which the intervention provides a net benefit. I also discuss the potential use of risk models in allocating prevention resources under cost constraints. High discriminatory accuracy of the risk model, in addition to good calibration, is desirable in this application, and the risk assessment should not be expensive in comparison with the intervention.