Abstract

A CLINICIAN’S GUIDE TO STUDY DESIGNS IN CLINICAL TRIALS AND OBSERVATIONAL RESEARCH

Pallab Mandal, Soumya Chakraborty, Pradip Kundu, Prof. Dr. Sanmoy Karmakar*

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Abstract

This primer delineates the panoply of study designs crucial for both clinical trials and observational research, eschewing the jejune summaries often encountered. A clinician's perspicacious understanding of these methodologies is paramount for judiciously appraising the veracity of medical literature and fostering evidence-based praxis. We begin with interventional designs, explicating the rigor of Randomized Controlled Trials (RCTs)—the gold standard—including the nuances of superiority, non-inferiority, and adaptive designs. These designs offer the highest level of causal inference due to their capacity to mitigate confounding through randomisation. Subsequently, we examine observational paradigms, which, though susceptible to residual bias, are often essential for addressing questions of aetiology, prognosis, and real-world effectiveness. These encompass cohort studies (prospective and retrospective), case-control studies (ideal for rare outcomes), and cross-sectional surveys. The inherent limitations of each design, particularly concerning selection and information bias, are adumbrated. Finally, we emphasize the imperative for clinicians to recognize the hierarchy of evidence, ensuring that research findings—from pragmatic trials to large registries—are appropriately contextualized and synthesized for optimal patient care. This guide serves as an invaluable tool for navigating the epistemological landscape of modern clinical investigation.

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