clinical study design
{{Short description|Plan for research in clinical medicine}}
{{Redirect|Study design|study design most generally, across sciences|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 .Miquel Porta (2014) "[http://global.oup.com/academic/product/a-dictionary-of-epidemiology-9780199976737?cc=us&lang=en A dictionary of epidemiology]", 6th edn, New York: Oxford University Press. {{ISBN|9780199976737}}. 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){{Cite web|url=https://www.noclor.nhs.uk/imp|title=Investigational Medicinal Product (IMP) | Noclor|website=www.noclor.nhs.uk|access-date=2019-11-19|archive-date=2020-09-26|archive-url=https://web.archive.org/web/20200926193310/https://www.noclor.nhs.uk/imp|url-status=dead}} 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).{{cite web |url=https://promedica-intl.com/blog/clinical-study-management-2/ |title=Clinical Study Management |work=ProMedica International |author=Ann |date=April 14, 2006 |access-date=June 4, 2019}} 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.{{cite web |url=https://www.medicalnewstoday.com/articles/278779.php |title=How do clinical trials work and who can participate? |work=Medical News Today |last=Nichols |first=Hannah |date=May 18, 2018 |access-date=June 4, 2019}}
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{{cite web |url=https://www.medicinenet.com/script/main/art.asp?articlekey=39532 |title=Randomized control trial |work=Medicine Net |last=Shiel |first=William C. Jr. |date=December 21, 2018 |access-date=June 4, 2019}}
- Blind trial{{cite web |url=https://www.bmj.com/rapid-response/2011/10/31/what-single-blind-trial |title=Are these data real? Statistical methods for the detection of data fabrication in clinical trials |work=The BMJ |date=July 28, 2005 |access-date=June 4, 2019}}
- Non-blind trial{{cite web |url=https://www.medicinenet.com/script/main/art.asp?articlekey=25411 |title=Nonblinded study |work=Medicine Net |last=Shiel |first=William C. Jr. |date=December 21, 2018 |access-date=June 4, 2019}}
- Adaptive clinical trial{{cite journal |title=Adaptive design clinical trials: Methodology, challenges and prospect |last1=Mahajan |first1=Rajiv |last2=Gupta |first2=Kapil |date=August 2012 |pmc=2941608 |pmid=20927243 |doi=10.4103/0253-7613.68417 |volume=42 |issue=4|pages=201–7 |journal=Indian Journal of Pharmacology |doi-access=free }}
- Platform Trials
- Nonrandomized trial (quasi-experiment){{cite web |url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/nonrandomized-clinical-trial |title=NCI Dictionary of Cancer Terms |work=National Cancer Institute |date=2 February 2011 |access-date=June 4, 2019}}
- Interrupted time series design{{cite journal |title=Regression based quasi-experimental approach when randomisation is not an option: interrupted time series analysis |journal=The BMJ |date=June 9, 2015 |doi=10.1136/bmj.h2750 |last1=Kontopantelis |first1=E. |last2=Doran |first2=T. |last3=Springate |first3=D. A. |last4=Buchan |first4=I. |last5=Reeves |first5=D. |volume=350 |pages=h2750 |pmid=26058820 |pmc=4460815 }} (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
- Case series{{cite web |url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/case-series |title=NCI Dictionary of Cancer Terms |work=National Cancer Institute |date=2 February 2011 |access-date=June 4, 2019}}
- Population study{{cite web |url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/population-study |title=NCI Dictionary of Cancer Terms |work=National Cancer Institute |date=2 February 2011 |access-date=June 4, 2019}}
2. Analytical
- Cohort study{{cite journal |title=Clarifying the distinction between case series and cohort studies in systematic reviews of comparative studies: potential impact on body of evidence and workload |last1=Mathes |first1=Tim |last2=Pieper |first2=Dawid |date=July 17, 2017 |pmc=5513097 |pmid=28716005 |doi=10.1186/s12874-017-0391-8 |volume=17 |issue=1|page=107 |journal=BMC Med Res Methodol |doi-access=free }}
- Prospective cohort{{cite web |url=https://www.cancer.gov/publications/dictionaries/cancer-terms/def/prospective-cohort-study |title=NCI Dictionary of Cancer Terms |work=National Cancer Institute |date=2 February 2011 |access-date=June 4, 2019}}
- 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.{{cn|date=August 2022}}
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.{{cn|date=August 2022}}
=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.{{cite web|url=http://appliedclinicaltrialsonline.findpharma.com/appliedclinicaltrials/Drug+Development/Flu-Season-Diseases-Affect-Trials/ArticleStandard/Article/detail/652128|title=Flu, Season, Diseases Affect Trials|publisher=Applied Clinical Trials Online|author1=Yamin Khan|author2=Sarah Tilly|access-date=26 February 2010|archive-url=https://web.archive.org/web/20110711003335/http://appliedclinicaltrialsonline.findpharma.com/appliedclinicaltrials/Drug+Development/Flu-Season-Diseases-Affect-Trials/ArticleStandard/Article/detail/652128|archive-date=11 July 2011|url-status=dead}}{{cite web|url=http://www.pharm-olam.com/pdf/POI-Seasonality.pdf|title=Seasonality: The Clinical Trial Manager's Logistical Challenge|publisher=published by: Pharm-Olam International (POI)|author1=Yamin Khan|author2=Sarah Tilly|access-date=26 April 2010|archive-url=https://web.archive.org/web/20110715072506/http://www.pharm-olam.com/pdf/POI-Seasonality.pdf|archive-date=15 July 2011|url-status=dead}}
Other terms
- The term retrospective study is sometimes used as another term for a case-control study.{{cite web |url=https://www.statsdirect.com/help/basics/prospective.htm |title=Prospective vs. Retrospective Studies |work=Stats Direct |access-date=May 30, 2019}} 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|date=June 2019}}
- 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
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- Conceptual framework
- Epidemiological methods
- Epidemiology
- Experimental control
- Meta-analysis
- Operationalization
- Academic clinical trials
- Design of experiments
- Research design
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References
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External links
- [http://www.jerrydallal.com/LHSP/STUDY.HTM Some aspects of study design] Tufts University web site
- [https://web.archive.org/web/20051016100803/http://imsdd.meb.uni-bonn.de/cancernet/902570.html Comparison of strength] Description of study designs from the National Cancer Institute
{{Medical research studies|state=expanded}}
{{Statistics|applications|state=collapsed}}