Clinical study design

"Study design" redirects here. For study design most generally, across sciences, see design of experiments.

Clinical study design is the formulation of clinical trials and other experiments, as well as observational studies, in medical research involving human beings and involving clinical aspects, including epidemiology . ^[1] It is the design of experiments as applied to these fields. The goal of a clinical study is to assess the safety, efficacy, and / or the mechanism of action of an investigational medicinal product (IMP) ^[2] or procedure, or new drug or device that is in development, but potentially not yet approved by a health authority (e.g. Food and Drug Administration). ^[3] It can also be to investigate a drug, device or procedure that has already been approved but is still in need of further investigation, typically with respect to long-term effects or cost-effectiveness. ^[4]

Some of the considerations here are shared under the more general topic of design of experiments but there can be others, in particular related to patient confidentiality and medical ethics.

Outline of types of designs for clinical studies

Treatment studies

• Randomized controlled trial ^[5]
  • Blind trial ^[6]
  • Non-blind trial ^[7]
• Adaptive clinical trial ^[8]
  • Platform Trials
• Nonrandomized trial (quasi-experiment) ^[9]
  • Interrupted time series design ^[10] (measures on a sample or a series of samples from the same population are obtained several times before and after a manipulated event or a naturally occurring event) - considered a type of quasi-experiment

Observational studies

1. Descriptive

• Case report ^[11]
• Case series ^[12]
• Population study ^[13]

2. Analytical

• Cohort study ^[11]
  • Prospective cohort ^[14]
  • Retrospective cohort
  • Time series study
• Case-control study
  • Nested case-control study
• Cross-sectional study
  • Community survey (a type of cross-sectional study)
• Ecological study

Important considerations

When choosing a study design, many factors must be taken into account. Different types of studies are subject to different types of bias. For example, recall bias is likely to occur in cross-sectional or case-control studies where subjects are asked to recall exposure to risk factors. Subjects with the relevant condition (e.g. breast cancer) may be more likely to recall the relevant exposures that they had undergone (e.g. hormone replacement therapy) than subjects who don't have the condition.^{[ citation needed ]}

The ecological fallacy may occur when conclusions about individuals are drawn from analyses conducted on grouped data. The nature of this type of analysis tends to overestimate the degree of association between variables.^{[ citation needed ]}

Seasonal studies

Conducting studies in seasonal indications (such as allergies, Seasonal Affective Disorder, influenza, and others) can complicate a trial as patients must be enrolled quickly. Additionally, seasonal variations and weather patterns can affect a seasonal study. ^{[15] [16]}

Other terms

• The term retrospective study is sometimes used as another term for a case-control study. ^[17] This use of the term "retrospective study" is misleading, however, and should be avoided because other research designs besides case-control studies are also retrospective in orientation.^{[ citation needed ]}
• Superiority trials are designed to demonstrate that one treatment is more effective than a given reference treatment. This type of study design is often used to test the effectiveness of a treatment compared to placebo or to the currently best available treatment.
• Non-inferiority trials are designed to demonstrate that a treatment is at least not appreciably less effective than a given reference treatment. This type of study design is often employed when comparing a new treatment to an established medical standard of care, in situations where the new treatment is cheaper, safer or more convenient than the reference treatment and would therefore be preferable if not appreciably less effective.
• Equivalence trials are designed to demonstrate that two treatments are equally effective.
• When using "parallel groups", each patient receives one treatment; in a "crossover study", each patient receives several treatments but in different order.
• A longitudinal study assesses research subjects over two or more points in time; by contrast, a cross-sectional study assesses research subjects at only one point in time (so case-control, cohort, and randomized studies are not cross-sectional).

See also

• Conceptual framework
• Epidemiological methods
• Epidemiology
• Experimental control
• Meta-analysis
• Operationalization
• Academic clinical trials
• Design of experiments
• Research design

References

1. Miquel Porta (2014) "A dictionary of epidemiology", 6th edn, New York: Oxford University Press. ISBN   9780199976737.
2. "Investigational Medicinal Product (IMP) | Noclor". www.noclor.nhs.uk. Archived from the original on 2020-09-26. Retrieved 2019-11-19.
3. Ann (April 14, 2006). "Clinical Study Management". ProMedica International. Retrieved June 4, 2019.
4. Nichols, Hannah (May 18, 2018). "How do clinical trials work and who can participate?". Medical News Today. Retrieved June 4, 2019.
5. Shiel, William C. Jr. (December 21, 2018). "Randomized control trial". Medicine Net. Retrieved June 4, 2019.
6. "Are these data real? Statistical methods for the detection of data fabrication in clinical trials". The BMJ. July 28, 2005. Retrieved June 4, 2019.
7. Shiel, William C. Jr. (December 21, 2018). "Nonblinded study". Medicine Net. Retrieved June 4, 2019.
8. Mahajan, Rajiv; Gupta, Kapil (August 2012). "Adaptive design clinical trials: Methodology, challenges and prospect". Indian Journal of Pharmacology. 42 (4): 201–7. doi: 10.4103/0253-7613.68417 . PMC   2941608 . PMID   20927243.
9. "NCI Dictionary of Cancer Terms". National Cancer Institute. 2 February 2011. Retrieved June 4, 2019.
10. Kontopantelis, E.; Doran, T.; Springate, D. A.; Buchan, I.; Reeves, D. (June 9, 2015). "Regression based quasi-experimental approach when randomisation is not an option: interrupted time series analysis". The BMJ. 350: h2750. doi:10.1136/bmj.h2750. PMC   4460815 . PMID   26058820.
11. Mathes, Tim; Pieper, Dawid (July 17, 2017). "Clarifying the distinction between case series and cohort studies in systematic reviews of comparative studies: potential impact on body of evidence and workload". BMC Med Res Methodol. 17 (1): 107. doi: 10.1186/s12874-017-0391-8 . PMC   5513097 . PMID   28716005.
12. "NCI Dictionary of Cancer Terms". National Cancer Institute. 2 February 2011. Retrieved June 4, 2019.
13. "NCI Dictionary of Cancer Terms". National Cancer Institute. 2 February 2011. Retrieved June 4, 2019.
14. "NCI Dictionary of Cancer Terms". National Cancer Institute. 2 February 2011. Retrieved June 4, 2019.
15. Yamin Khan; Sarah Tilly. "Flu, Season, Diseases Affect Trials". Applied Clinical Trials Online. Archived from the original on 11 July 2011. Retrieved 26 February 2010.
16. Yamin Khan; Sarah Tilly. "Seasonality: The Clinical Trial Manager's Logistical Challenge" (PDF). published by: Pharm-Olam International (POI). Archived from the original (PDF) on 15 July 2011. Retrieved 26 April 2010.
17. "Prospective vs. Retrospective Studies". Stats Direct. Retrieved May 30, 2019.

External links

• Some aspects of study design Tufts University web site
• Comparison of strength Description of study designs from the National Cancer Institute