Observational Clinical Study

An Observational Clinical Study is a clinical study in which a clinical researcher observes natural relationships between factors and outcomes without interceding or acting upon clinical trial participants.

AKA: Epidemiological Clinical Study.
Context:
- It can (typically) a retrospective and uncontrolled clinical study.
- …
Example(s):
- a Cross-Sectional Clinical Study.
- a Case-Control Clinical Study.
- a Cohort Clinical Study.
- a Case-Crossover Clinical Study.
- a Proportional Mortality Ratio Clinical Study,
- an Ecological Clinical Study.
- …
Counter-Example(s):
- Interventional Clinical Study, such as: an Uncontrolled Clinical Intervention Study.
- Diagnostic Clinical Study.
See: Disease Exposure Measure, Clinical Exposure-Outcome Relationship, Parallel Clinical Trial, Crossover Clinical Trial, Adaptive Clinical Trial, Multi-Arm Clinical Trial, Dynamic Clinical Trial.

References

2022a

(ClinicalTrials.gov, 2022) ⇒ https://clinicaltrials.gov/ct2/about-studies/glossary Retrieved:2022-02-13.
- QUOTE: ...
  - Observational study: A type of clinical study in which participants are identified as belonging to study groups and are assessed for biomedical or health outcomes. Participants may receive diagnostic, therapeutic, or other types of interventions, but the investigator does not assign participants to a specific interventions/treatment.
  - Observational study model: The general design of the strategy for identifying and following up with participants during an observational study. Types of observational study models include cohort, case-control, case-only, case-cross-over, ecologic or community studies, family-based, and other.

2022b

(ClinicalTrials.gov, 2022) ⇒ https://clinicaltrials.gov/ct2/about-studies/learn Retrieved:2022-02-11.
- QUOTE: ... In an observational study, investigators assess health outcomes in groups of participants according to a research plan or protocol. Participants may receive interventions (which can include medical products such as drugs or devices) or procedures as part of their routine medical care, but participants are not assigned to specific interventions by the investigator (as in a clinical trial). For example, investigators may observe a group of older adults to learn more about the effects of different lifestyles on cardiac health.

2016

(Grant, 2016) ⇒ William B. Grant (2016). "The role of geographical ecological studies in identifying diseases linked to UVB exposure and/or vitamin D". In: Dermato Endocrinology 8(1):e1137400. DOI:10.1080/19381980.2015.1137400.
- QUOTE: Four methods exist to determine whether UVB exposure and vitamin D affect disease outcomes: ecological studies, observational studies, laboratory studies, and clinical trials.
- Ecological studies can be of 2 types:
  - Geographical. Health outcomes and risk-modifying factors are averaged for populations divided along geographical lines.
  - Temporal. Health outcomes are examined for seasonal variations or trends.
- Observational studies come in several forms:
  - Case–control. Risk-modifying factors measured at the time of disease diagnosis.
  - Cohort and nested case–control. Subjects are enrolled in a study, risk-modifying factors are assessed, and then the cohort is monitored (for up to many years). Those who develop diseases are compared with like individuals who did not.
  - Cross-sectional. An entire population is sampled, with health status and health parameters and risk-modifying factors measured.
- Laboratory studies are generally of 3 types:
  - Animal studies. Animal models of various diseases are challenged with various agents.
  - Detailed cell and tissue analysis. Cells and tissues from patients can be examined for genetic variations, etc.

In clinical trials, people are enrolled and randomly assigned to take a substance or a placebo for a specified time. The object is to see whether taking the agent yields a better result for the outcome of interest.

2014

(Thiese, 2014) ⇒ Matthew S. Thiese. (2014). “Observational and Interventional Study Design Types; An Overview.” In: Biochemia Medica (Zagreb). Journal, 24(2).
- QUOTE: Observational study designs, also called epidemiologic study designs, are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods. Observational study designs include ecological designs, cross-sectional, case-control, case-crossover, retrospective and prospective cohorts. An important subset of observational studies is diagnostic study designs, which evaluate the accuracy of diagnostic procedures and tests as compared to other diagnostic measures. These include diagnostic accuracy designs, diagnostic cohort designs, and diagnostic randomized controlled trials.
  Epidemiological and interventional research studies include three elements; 1) definition and measure of exposure in two or more groups, 2) measure of health outcome(s) in these same groups, and 3) statistical comparison made between groups to assess potential relationships between the exposure and outcome, all of which are defined by the researcher (...). The measure of exposure in epidemiologic studies may be tobacco use (“Yes” vs. “No”) to define the two groups and may be the treatment (Active drug vs. placebo) in interventional studies. Health outcome(s) can be the development of a disease or symptom (e.g. lung cancer) or curing a disease or symptom (e.g. reduction of pain)(...)
  Within primary research there are observational studies and interventional studies. Observational studies, also called epidemiological studies, are those where the investigator is not acting upon study participants, but instead observing natural relationships between factors and outcomes. Diagnostic studies are classified as observational studies, but are a unique category and will be discussed independently. Interventional studies, also called experimental studies, are those where the researcher intercedes as part of the study design.