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Source: Clinical Epidemiology and Evidence-Based Medicine
Authors: Tao Liyuan, Zhao Yiming
In recent years, some new terms have emerged in the field of clinical research methods, such as Comparative Effectiveness Research, Outcome Research, and Real-world Research. What do they mean, under what circumstances were they proposed, and what are their uses? Let’s get to know them together.
Comparative Effectiveness Research
Comparative Effectiveness Research (CER) translates to “比较效果研究” in Chinese, which sounds quite amusing. Comparative effectiveness? Most clinical research is about comparing effects, so what makes it special? Let’s look at the definition given by Amy Price et al.[1]: It generates and synthesizes evidence for preventive, diagnostic, therapeutic, and monitoring activities in healthcare by comparing benefits and risks. The purpose of CER is to help patients, clinicians, payers (insurance departments), and policymakers choose appropriate treatment measures to improve the quality of healthcare services at both the population and individual levels.
CER aims to produce medical service reports/papers targeted at different populations, which can be for patients, doctors, or insurance departments, etc. So, what are the research design forms of CER? In theory, the research design forms of CER are unlimited and can include systematic reviews/Meta-analyses, cross-sectional studies, case-control studies, cohort studies, and RCT, among others. The main characteristic of CER is that its research outcomes are “comparative effects,” providing practical guidance options for reference, often involving large-scale clinical research.
Outcome Research
Outcome research translates to “实效研究” in Chinese. So, what is outcome research? Stephanie J. Lee et al.[2] state in their paper: Extremally, all results are outcomes, thus all research is outcome research. This is certainly not appropriate. So how do we differentiate outcome research from clinical trials? The currently popular viewpoint is to look at whether the research observes effectiveness (effectiveness) or efficacy (efficacy); if it observes effectiveness, it is outcome research; if it observes efficacy, it is a clinical trial. The so-called “effectiveness” refers to studies conducted in clinical practice, where the subjects are a heterogeneous population, and the observed indicators are relatively long-term; while efficacy refers to studies conducted under clinical trials, where the subjects are a homogeneous population, and the observed indicators are short-term indicators or biomarkers.
However, effectiveness and efficacy sometimes share commonalities, as shown in the figure below:
When the outcome indicators are overall survival (OS), if it is observed in a Phase III drug clinical trial, then OS is efficacy, while in a community-based cohort study, it is effectiveness. Both outcome research and clinical trials can lead to clinical and policy decisions. Stephanie J. Lee et al. also provide a relatively broad definition of outcome research: Outcome research refers to studies on health status, quality of life, and effectiveness in clinical research, while not focusing on the efficacy of drug clinical trials and animal experiments. Thus, outcome research naturally includes all research forms other than drug clinical trials and animal experiments.
Real-world Research
Real-world research translates to “真实世界研究” in Chinese, which refers to studies conducted in the “real world,” meaning there are no strict limitations on the selection of study subjects and clinical drug treatments, making the research environment closer to clinical reality, thus allowing its results to be better applied in clinical practice. Real-world research not only includes practical clinical research but also observational studies, such as cohort studies.[3]
David Price et al.[4] point out: Its proposal is relative to traditional or classical RCT, emphasizing the external validity of the research, meaning the extrapolation of research results in clinical practice, which is similar to pragmatic clinical trials (pragmatic clinical trials), and it also includes various observational studies, such as cohort studies.
Next, let’s summarize the differences between classic RCT and pragmatic RCT: 
After understanding the concepts and characteristics of Comparative Effectiveness Research, Outcome Research, and Real-world Research, I personally summarize that: (1) These three types of research are proposed under specific environments, each with distinct characteristics; (2) The relationships among these three types of research are quite confused, with no strict distinctions; (3) These three types of research include various common research design types, such as cross-sectional, case-control, or cohort studies, and their naming also indicates research, which is different from study in English; (4) What is the value of their proposal? I believe their value lies more at the policy level, while their role in promoting the evolution of clinical research types is limited; (5) The above summary only represents personal views.
References:
[1]. A,P., C. P and B. R, comparative effectiveness research collaboration and precision medicine. Ann Neurosci, 2015. 22(3): p. 127-9.
[2]. Lee, S.J., C.C. Earle and J.C.Weeks, Outcomes research in oncology: history, conceptual framework, and trends in the literature. J Natl Cancer Inst, 2000. 92(3): p. 195-204.
[3]. Knottnerus, J.A. and P.Tugwell, Real world research. Journal of Clinical Epidemiology, 2010. 63(10):p. 1051-1052.
[4]. Price,D., et al., Real-world research and its importance in respiratory medicine. Breathe (Sheff), 2015. 11(1): p. 26-38.
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