{"id":27713,"date":"2024-02-25T11:30:00","date_gmt":"2024-02-25T16:30:00","guid":{"rendered":"https:\/\/www.hydroassoc.org\/research-101-an-explanation-of-clinical-trials-design\/"},"modified":"2024-10-25T13:05:59","modified_gmt":"2024-10-25T17:05:59","slug":"research-101-an-explanation-of-clinical-trials-design","status":"publish","type":"post","link":"https:\/\/www.hydroassoc.org\/research-101-an-explanation-of-clinical-trials-design\/","title":{"rendered":"Research 101: An Explanation of Clinical Trials Design"},"content":{"rendered":"\r\n\r\n\t<p>In <a href=\"\/research-101-levels-of-evidence-in-hydrocephalus-clinical-research-studies\/\" target=\"_blank\" rel=\"noopener\" data-feathr-click-track=\"true\" data-feathr-link-aids=\"5e8f8cf0d4f6e391de55d8ee\">Research 101: Levels of Evidence<\/a>, we discussed criteria that determines the <strong>value of a clinical study<\/strong>. Here we will discuss how the initial trial design can dictate the <strong>strength of a study<\/strong>.<\/p>\r\n<p>Clinical trials are either <strong>Experimental<\/strong> or<strong> Observational<\/strong>.<\/p>\r\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2015\/02\/15_02_26-Research-101-02-Study-Design-1024x383.png\" alt=\"Clinical Trial Design\" width=\"650\" height=\"243\" \/><\/p>\r\n<h2>Experimental<\/h2>\r\n<p>In Experimental studies, researchers assign patients to an experimental or control group. In a drug study, for instance, patients in the experimental groups receive the drug while patients in the control groups receive a placebo or sugar pill. The patients may not know if they are receiving the experimental treatment or placebo, a practice known as <strong>blinding<\/strong>, which helps reduce bias. There are different levels of blinding: single-blind (only the participants are unaware of the group assignment), double-blind (both participants and investigators are unaware), and triple-blind (participants, investigators, and data analysts are unaware). Blinding is important to prevent bias in the interpretation of outcomes. If done correctly, randomized clinical trials have the highest level of experimental validity. <strong>Randomization<\/strong>, or randomly assigning patients to each of the groups, helps ensure equivalent treatment, and control groups and the prospective design helps ensure quality control over the data and timing of the intervention.<\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2015\/02\/Randomized.png\" alt=\"\" width=\"155\" height=\"78\"><\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<ul>\r\n<li>Level 1 Study: Randomized, Prospective, Control Group<\/li>\r\n<li>Participants are randomly assigned to an intervention and followed prospectively<\/li>\r\n<li>Provides most compelling evidence that a treatment causes an observed outcome<\/li>\r\n<\/ul>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<h2>Observational<\/h2>\r\n<p>In Observational studies, the researcher observes but does not intervene (no randomization). Observational studies can detect <strong>correlations<\/strong> between an outcome and test variable. Caution needs to be exercised, however, when assessing the likelihood that the test variable <strong>caused<\/strong> the outcome. In most cases, causality cannot be inferred. Observational studies are either <strong>Analytical<\/strong> or <strong>Descriptive<\/strong>.<\/p>\r\n<h3>Analytical<\/h3>\r\n<p>Analytical studies look at the relationship between an outcome and a variable. These studies can be further classified into different types based on design: cohort and case-control studies. <strong>Cohort studies<\/strong> follow participants over time, starting with an exposure and observing subsequent outcomes, while <strong>case-control studies<\/strong> look retrospectively at individuals with a particular condition (cases) and compare them to individuals without the condition (controls) to identify potential risk factors.<\/p>\r\n<p>The strength of an Analytical study is largely dependent on how similar the control and experimental groups are before exposure to the test variable. Systematic differences between the groups, like if one group had all women, for example, can make it hard to tell if the results are based on the test variable or on the initial differences between the groups. Large sample sizes can help because it&#8217;s more likely that there will be more variation or diversity within each group &#8211; it would be much harder to have an entire group only made up of women, the bigger the group gets.<\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2015\/02\/Cohort.png\" alt=\"\" width=\"155\" height=\"78\"><\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<ul>\r\n<li>Level 2 or 3 Study: Not Randomized, Prospective or Retrospective, Control Group<\/li>\r\n<li>Participants are non-randomly separated based on exposure or treatment.<\/li>\r\n<li><strong>Example:<\/strong> The Hydrocephalus Clinical Research Network (HCRN) tested a new shunt surgical protocol. Infection rates were compared before (control) and after (experimental) adopting the new protocol. Shunt infections decreased ~36% with the new protocol.<\/li>\r\n<\/ul>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p>____________________<\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2015\/02\/CaseControl.png\" alt=\"\" width=\"155\" height=\"78\"><\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<ul>\r\n<li>Level 3 Study: Not Randomized, Retrospective, Control Group<\/li>\r\n<li>Participants are separated based on the presence or absence of a disease. Participant history is then examined for prior exposure to the variable of interest.<\/li>\r\n<li>Shows correlations between variables and diseases but does not show causality<\/li>\r\n<\/ul>\r\n\r\n\r\n\r\n<h3>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 Descriptive<\/h3>\r\n<p>Descriptive studies, on the other hand, gather information such as demographics, etiology, disease history, and treatment history. They do not aim to establish causality between variables and outcomes but rather provide background information to generate hypotheses for future research. In other words, it cannot determine if X causes Y. It only gathers information. Descriptive studies can be further categorized into types like cross-sectional studies,\u00a0case series, and case reports.<\/p>\r\n<p><strong>Cross-sectional studies<\/strong> collect data from a group of people at a specific point in time, like taking a snapshot. These studies help researchers find out how common a condition is in a population and look for patterns or connections between different factors, but they cannot show whether one thing causes another. <strong>Case series<\/strong> look at a group of people who all have the same condition or have received the same treatment. Researchers describe what happened to patients, but since there is no comparison to a control group (people without the condition), the results cannot be used to draw conclusions about cause and effect. <strong>Case reports<\/strong> are detailed accounts about the experiences of a single person or a very small number of people who have a unique condition or treatment. While they can offer new ideas or raise questions for further research, they are the lowest level of evidence (Level 5) in clinical research because they lack a control group and cannot be used to prove any clinical evidence on their own. However, they play a valuable role in generating new hypotheses, offering insights that may guide future research.<\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2015\/02\/CrossSectional.png\" alt=\"\" width=\"155\" height=\"78\"><\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<ul>\r\n<li>Level 4: Epidemiological &#8216;Snapshot&#8217;, No Control Group<\/li>\r\n<li>Collection of data from a population or representative subset at one point in time<\/li>\r\n<li>Often used to obtain prevalence numbers and correlations.<\/li>\r\n<\/ul>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p>____________________<\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2015\/02\/CaseSeries.png\" alt=\"\" width=\"155\" height=\"78\"><\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<ul>\r\n<li>Level 4: Not Randomized, Retrospective, No Control Group<\/li>\r\n<li>Retrospective account of multiple patients with the same injury or treatment. There is no control or comparison group.<\/li>\r\n<li>Useful for generating hypotheses, but cannot assess correlations due to the small sample size. The results are not generalizable<\/li>\r\n<\/ul>\r\n<p>\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0____________________<\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2015\/02\/CaseReport.png\" alt=\"\" width=\"155\" height=\"78\"><\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<ul>\r\n<li>Level 5: Not Randomized, Retrospective, No Control Group<\/li>\r\n<li>Descriptive account of one patient with no control group<\/li>\r\n<li>Cannot draw any conclusions about exposures, treatments, or interventions<\/li>\r\n<\/ul>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<h2>Meta-Analysis<\/h2>\r\n<p>Separate from primary study designs is the meta-analysis. A meta-analysis is research method where scientists conduct a systematic review of existing data and combine the results from several different studies on the same topic to get a clearer overall picture. The strength of the meta-analysis is dependent on the strengths of the studies included in the analysis. When done carefully, meta-analyses are considered the strongest evidence for answering questions about treatments or health conditions. This is because they look at all the available research, rather than just one study. However, even if all of the studies included in a meta-analysis are randomized, a meta-analysis cannot be considered randomized.<\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2015\/02\/MetaAnalysis.png\" alt=\"\" width=\"155\" height=\"78\"><\/p>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<ul>\r\n<li>Range from Level 1 to 3: Not Randomized<\/li>\r\n<li>Systematic review of other studies<\/li>\r\n<li>Often used to &#8216;combine&#8217; studies with small sample sizes to increase the power (ability to find a significant difference) of the studies.<\/li>\r\n<\/ul>\r\n<img decoding=\"async\" src=\"https:\/\/www.hydroassoc.org\/wp-content\/plugins\/advanced-wp-columns\/assets\/js\/plugins\/views\/img\/1x1-pixel.png\" alt=\"\">\r\n<p>&nbsp;<\/p>\r\n<h5>Other entries in our Research 101 Blog Series with Dr. Koschnitzky:<\/h5>\r\n<a href=\"\/research-101-randomization\/\" data-feathr-click-track=\"true\" data-feathr-link-aids=\"5e8f8cf0d4f6e391de55d8ee\">Research 101: Randomization<br \/>\r\n<\/a><br \/>\r\n<a href=\"\/research-101-the-importance-of-sample-size\/\" data-feathr-click-track=\"true\" data-feathr-link-aids=\"5e8f8cf0d4f6e391de55d8ee\">Research 101: The Importance of Sample Size<br \/>\r\n<\/a><br \/>\r\n<a href=\"\/research-101-junction-junction-whats-your-function\/\" data-feathr-click-track=\"true\" data-feathr-link-aids=\"5e8f8cf0d4f6e391de55d8ee\">Research 101: Junction, Junction, What&#8217;s Your Function?<\/a>\r\n<p><a href=\"\/research-101-generalizability\/\" data-feathr-click-track=\"true\" data-feathr-link-aids=\"5e8f8cf0d4f6e391de55d8ee\">Research 101: Generalizability<\/a><\/p>\r\n\r\n\r\n            <div id=\"daexthefup-container\"\r\n                 class=\"daexthefup-container daexthefup-layout-stacked daexthefup-alignment-center\"\r\n                 data-post-id=\"27713\">\r\n\r\n                <div class=\"daexthefup-feedback\">\r\n                    <div class=\"daexthefup-text\">\r\n                        <h3 class=\"daexthefup-title\">Was this resource helpful?<\/h3>\r\n                    <\/div>\r\n                    <div class=\"daexthefup-buttons-container\">\r\n                        <div class=\"daexthefup-buttons\">\r\n\t\t\t\t\t\t\t\r\n            <div class=\"daexthefup-yes daexthefup-button daexthefup-button-type-text\" data-value=\"1\">\r\n                <div class=\"daexthefup-button-text\">Yes<\/div>\r\n            <\/div>\r\n\r\n\t\t\t\t\t\t\t\t\t\t\r\n            <div class=\"daexthefup-no daexthefup-button daexthefup-button-type-text\" data-value=\"0\">\r\n                <div 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research.<\/p>\n","protected":false},"author":8,"featured_media":27714,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_helpful_pro_status":1,"_searchwp_excluded":"","inline_featured_image":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[40,32,1207],"tags":[1221],"post_folder":[],"class_list":["post-27713","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research-updates","category-ha-blog","category-resources","tag-research-updates"],"acf":[],"jetpack_featured_media_url":"https:\/\/www.hydroassoc.org\/wp-content\/uploads\/2021\/03\/ControlTrial.jpg","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/posts\/27713","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/users\/8"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/comments?post=27713"}],"version-history":[{"count":0,"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/posts\/27713\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/media\/27714"}],"wp:attachment":[{"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/media?parent=27713"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/categories?post=27713"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/tags?post=27713"},{"taxonomy":"post_folder","embeddable":true,"href":"https:\/\/www.hydroassoc.org\/wp-json\/wp\/v2\/post_folder?post=27713"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}