Epidemiological Studies: Principles and Essentials

There are different types of epidemiological studies, including cohort studies, case-control studies, cross-sectional studies, and randomized controlled trials. These epidemiological studies can be used for guiding physicians in their decision-making process regarding prognosis, diagnosis, and treatment. It is important to note that some types of epidemiological studies are more appropriate for prognosis, and other types are used for selecting a diagnosis and a treatment option (Fletcher, Fletcher, & Fletcher, 2013).

Therefore, the impact of epidemiological studies on the knowledge regarding prognosis, diagnosis, and treatment is significant because healthcare providers make evidence-based medical decisions and choose diagnostic and treatment options referring to the available research in the field.

Prognosis is associated with describing specifics of a course of a certain disease. Studies of prognosis are based on the framework of such epidemiological researches as cohort and case-control studies. In this context, the focus is on determining prognostic factors or characteristics of individuals that can lead to a certain outcome for patients. In cohort studies, people are selected according to their potential exposure to risk factors or prognostic factors, as it is in the case of studies of prognosis (Centers for Disease Control and Prevention, 2012; Fletcher et al., 2013).

These cohort studies can be retrospective and prospective, and both types contribute to determining factors that are associated with the development of a particular disease. The example of this type of epidemiological studies is the British cohort study involving 3,875 people to examine how often individuals with irritable bowel syndrome visit physicians (Fletcher et al., 2013). In turn, case-control studies are important to examine the frequency of the selected medical condition among the representatives of a certain population. Thus, cohort and case-control studies impact the medical knowledge regarding prognosis while helping in identifying factors causing the course of illnesses.

In diagnosing, clinicians usually apply a variety of diagnostic tests and assessments to decide on the condition that causes certain symptoms in a patient. However, not all diagnostic procedures, techniques, and approaches can be discussed as equally effective (U.S. Preventive Services Task Force, 2014). Healthcare providers refer to such studies as cross-sectional ones and randomized controlled trials to select the most appropriate approach to diagnosing a certain condition.

In cross-sectional studies, the focus is on examining a medical condition that is currently present in patients. The emphasis from provoking factors is shifted to actual symptoms of a disease. Randomized controlled trials demonstrate differences in the effectiveness of using various diagnostic measures. For example, to diagnose conditions causing low back pain in patients, it is necessary to refer to cross-sectional studies demonstrating what conditions usually provoke this type of pain in proportions or percentages.

Additionally, it is also necessary to focus on studies reporting the effectiveness of using magnetic resonance imaging for diagnosing in this case (Fletcher et al., 2013). The presence of epidemiological studies influences the choice of diagnostic tools and helps physicians focus on important disease symptoms.

Treatment is related to the selection of a certain plan of actions in order to cope with a patient’s disease. To select the most appropriate and effective treatment, healthcare providers usually refer to the results of such epidemiological studies as randomized controlled trials that are similar in their findings to experimental studies (Fletcher et al., 2013). The reason is that, in randomized controlled trials, treatment interventions are usually randomly allocated to different groups of patients in order to examine the effectiveness of the intervention without any bias. For instance, a randomized controlled trial organized and conducted in Scotland was selected for testing the effectiveness of different approaches to asthma management (Fletcher et al., 2013).

In this context, much attention should be paid to selecting participants in order to avoid the impact of certain uncontrolled factors and bias on the results of a study (Centers for Disease Control and Prevention, 2012). From this perspective, the use of randomized controlled trials directly influences the knowledge regarding treatment because these researches usually demonstrate the most reliable and effective interventions to use when coping with different medical conditions.

Having analyzed different types of epidemiological studies and their use in various prognosis, diagnosis, and treatment activities of healthcare providers, it is possible to state that these studies usually guide medical workers’ actions. From this perspective, the impact of these studies on the knowledge, theory, and practice in this sphere is significant. Healthcare professionals actively utilize the results of cohort studies in order to understand what populations and specific groups of patients are more exposed to the development of a certain disease.

In addition, these activities are important for creating a relevant prognosis for a particular medical condition for the selected population. Furthermore, medical workers usually refer to the findings of randomized controlled trials when they decide on a diagnosis and the treatment to apply. The reason is that these important decisions need to be evidence-based, and findings of randomized controlled trials allow healthcare providers to choose the most effective interventions in order to guarantee positive outcomes for their patients.


Centers for Disease Control and Prevention. (2012). Principles of epidemiology in public health practice: An introduction to applied epidemiology and biostatistics. Web.

Fletcher, R. H., Fletcher, S. W., & Fletcher, G. S. (2013). Clinical epidemiology: The essentials (5th ed.). Baltimore, MD: Lippincott Williams & Wilkins.

U.S. Preventive Services Task Force. (2014). The guide to clinical preventive services: Recommendations of the U.S. Preventive Services Task Force. Web.