Medical research is classified into primary and secondary research. There are three main types of primary research: basic (experimental), clinical, and epidemiological research. Secondary research provides a summary of available studies through reviews and meta-analyses.
Basic research
Basic or experimental medical research seeks to advance our understanding of the fundamental biological and physiological processes underlying health and disease. It lays the groundwork for future medical advancements and innovations by uncovering the intricate workings of biological systems. Basic medical research efforts are often a collaboration of various scientific disciplines such as biochemistry, microbiology, physiology, and pharmacology. Basic research may involve laboratory experiments with mice or other lab animals, cell cultures, tissue samples, genetic material, drugs, and other materials, and often results in the development and improvement of analytical procedures, imaging procedures, biometric procedures, and gene sequencing.
Clinical Research
Clinical research plays a critical role in advancing medical knowledge, developing new treatments and therapies, and improving healthcare practices. Clinical studies include both interventional (or experimental) studies and noninterventional (or observational) studies.
An interventional clinical study (or clinical trial) is any study performed on man with the purpose of studying or demonstrating the clinical or pharmacological effects of drugs, to establish side effects, or to investigate absorption, distribution, metabolism or elimination, with the aim of providing clear evidence of the efficacy or safety of the drug. Interventional studies also include studies on medical devices and studies in which surgical, physical or psychotherapeutic procedures are examined. The aim of an interventional study is to compare treatment procedures within a patient population, which should exhibit as few as possible internal differences, apart from the treatment. Interventional clinical studies should ideally include randomization – wherein the patients are allocated by chance to the therapy groups - and blinding, which is a suitable method to avoid bias. Single blinding is when the patient is unaware of which treatment he is receiving, while double blinding is when neither the patient nor the investigator knows which treatment is planned. In clinical trials, enrolled patients not receiving the experimental treatment receive the standard of care treatment that they would get if they were not enrolled in a clinical study.
In contrast, a noninterventional clinical study is an observational study, in which patients are given an individually specified therapy. The knowledge from the treatment of patients enrolled in the study is analyzed using epidemiological methods. The diagnosis, treatment and monitoring are not performed according to a previously specified study protocol, but exclusively according to medical practice.
Epidemiological Research
Epidemiological research focuses on studying the patterns, causes, and effects of health-related events and diseases within populations. The main goal of epidemiological research is to understand the distribution and determinants of health and disease across time periods to inform public health policies, interventions, and strategies. This field is crucial for identifying risk factors, preventing the spread of diseases, and improving overall population health. Common methods used in epidemiologic studies include quality of life assessments, patient surveys, patient reported outcomes, questionnaires and surveys, observations, focus groups, interviews, etc.