Definitions, acceptability, limitations, and guidance in the use and reporting of surrogate end points in trials: a scoping review

A landscape of methodology and implementation of adaptive designs in cancer clinical trials

BACKGROUND

The use of adaptive designs in cancer trials has considerably increased worldwide in recent years, along with the release of various guidelines for their application. This systematic review aims to comprehensively summarize the key methodological and executive features of adaptive designs in cancer clinical trials.

METHODS

A comprehensive search from PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials was conducted to screen eligible clinical trials that employed adaptive designs and were conducted in cancer patients. The methodological and executive characteristics of adaptive designs were the main measurements extracted. Descriptive analyses, primarily consisting of frequency and percentage, were employed to analyzed and reported the data.

RESULTS

A total of 180 cancer clinical trials with adaptive designs were identified. The first three most common type of adaptive design was the group sequential design (n=114, 63.3 %), adaptive dose-finding design (n=22, 12.2 %), and adaptive platform design (n=16, 8.9 %). The results showed that 4.4 % (n=8) of trials conducted post hoc modifications, and around 29.4 % (n=53) did not provide the methods for controlling type I errors. Among phase II or above trials, 79.9 % (112/140) applied the surrogate endpoint as the primary outcome in these trials. Importantly, 27.2 % (49/180) of trials did not report clear information on the independent data monitoring committee (iDMC), and 13.3 % (n=24) without clear information on interim analyses. Interim analyses suggested 34.4 % (62/180) of trials being stopped for futility, 10.6 % (n=19) for efficacy, and 2.2 % (n=4) for safety concerns in the early stage.

CONCLUSIONS

This study emphasizes adaptive designs in cancer trials face significant challenges in their design or strict implementation according to protocol, which might significantly compromise the validity and integrity of trials. It is thus important for researchers, sponsors, and policymakers to actively oversee and guide their application.

Clinical pharmacy key performance indicators for hospital inpatient setting: a systematic review

BACKGROUND

Key performance indicators (KPIs) are quantifiable measures used to monitor the quality of health services. Implementation guidelines for clinical pharmacy services (CPS) do not specify KPIs.

AIM

To assess the quality of the studies that have developed KPIs for CPS in inpatient hospital settings.

METHOD

A systematic review was conducted by searching in Web of Science, Scopus, and PubMed, supplemented with citation analyses and grey literature searches, to retrieve studies addressing the development of KPIs in CPS for hospital inpatients. Exclusions comprised drug- or disease-specific studies and those not written in English, French, Portuguese, or Spanish. The Appraisal of Indicators through Research and Evaluation (AIRE) instrument assessed methodological quality. Domain scores and an overall score were calculated using an equal-weight principle. KPIs were classified into structure, process, and outcome categories. The protocol is available at https://doi.org/10.17605/OSF.IO/KS2G3 .

RESULTS

We included thirteen studies that collectively developed 225 KPIs. Merely five studies scored over 50% on the AIRE instrument, with domains #3 (scientific evidence) and #4 (formulation and usage) displaying low scores. Among the KPIs, 8.4% were classified as structure, 85.8% as process, and 5.8% as outcome indicators. The overall methodological quality did not exhibit a clear association with a major focus on outcomes. None of the studies provided benchmarking reference values.

CONCLUSION

The KPIs formulated for evaluating CPS in hospital settings primarily comprised process measures, predominantly suggested by pharmacists, with inadequate evidence support, lacked piloting or validation, and consequently, were devoid of benchmarking reference values.

Surrogate endpoints: a key concept in clinical epidemiology

Surrogate endpoints are biomarkers or intermediate outcomes that are used as substitutes for clinical outcomes of interest, often to expedite research or decision-making. In contrast, patient-important (or patient-centered) outcomes are health outcomes that are of direct relevance and importance to patients themselves; clinical trials may have measured the impact of the intervention on other endpoints related to, but different from, those of primary importance to patients. This article aims to elaborate on the use and understanding of surrogate endpoints. There should be a well-understood and scientifically grounded relationship between the surrogate (replacement) and the patient-important (target) endpoint it is intended to represent. It should be biologically plausible that changes in the surrogate will consistently and predictably reflect changes in the patient-important endpoint. The surrogate endpoint should show a threshold effect, meaning that a specific change (or state) in the surrogate with an intervention (relative to the comparator) is associated with a predictable (change in the) patient-important outcome. This helps establish a meaningful cutoff or target for the treatment effect on the surrogate endpoint. While surrogate endpoints offer advantages in certain situations, it is important to remember that their use requires careful validation to ensure they reliably predict the true clinical outcome. The validity of "surrogate endpoints" should be supported by robust scientific evidence and rigorous evaluation before these can be considered and labeled as surrogate endpoints.

A framework for the definition and interpretation of the use of surrogate endpoints in interventional trials

Background

Interventional trials that evaluate treatment effects using surrogate endpoints have become increasingly common. This paper describes four linked empirical studies and the development of a framework for defining, interpreting and reporting surrogate endpoints in trials.

Methods

As part of developing the CONSORT (Consolidated Standards of Reporting Trials) and SPIRIT (Standard Protocol Items: Recommendations for Interventional Trials) extensions for randomised trials reporting surrogate endpoints, we undertook a scoping review, e-Delphi study, consensus meeting, and a web survey to examine current definitions and stakeholder (including clinicians, trial investigators, patients and public partners, journal editors, and health technology experts) interpretations of surrogate endpoints as primary outcome measures in trials.

Findings

Current surrogate endpoint definitional frameworks are inconsistent and unclear. Surrogate endpoints are used in trials as a substitute of the treatment effects of an intervention on the target outcome(s) of ultimate interest, events measuring how patients feel, function, or survive. Traditionally the consideration of surrogate endpoints in trials has focused on biomarkers (e.g., HDL cholesterol, blood pressure, tumour response), especially in the medical product regulatory setting. Nevertheless, the concept of surrogacy in trials is potentially broader. Intermediate outcomes that include a measure of function or symptoms (e.g., angina frequency, exercise tolerance) can also be used as substitute for target outcomes (e.g., all-cause mortality)-thereby acting as surrogate endpoints. However, we found a lack of consensus among stakeholders on accepting and interpreting intermediate outcomes in trials as surrogate endpoints or target outcomes. In our assessment, patients and health technology assessment experts appeared more likely to consider intermediate outcomes to be surrogate endpoints than clinicians and regulators.

Interpretation

There is an urgent need for better understanding and reporting on the use of surrogate endpoints, especially in the setting of interventional trials. We provide a framework for the definition of surrogate endpoints (biomarkers and intermediate outcomes) and target outcomes in trials to improve future reporting and aid stakeholders' interpretation and use of trial surrogate endpoint evidence.

Funding

SPIRIT-SURROGATE/CONSORT-SURROGATE project is Medical Research Council Better Research Better Health (MR/V038400/1) funded.