Title 2. TYPES OF CLINICAL STUDY DESIGNS.pdf ✅

PHARMD GURU Page 1 INTRODUCTION: Generally, if I have to explain in simple language, If someone wants to do a research or publish a research article, they have to follow a particular order, which you will better understand in Pharmacoepidemiology subject in Pharm.D fifth year. The following order should be followed: TYPES OF CLINICAL STUDY DESIGNS This 3rd step is called Clinical study design. We have to choose a specific design according to our research. This chapter is all about various types of study designs in clinical research.
PHARMD GURU Page 2  Interventional studies are also called Experimental studies. IN SIMPLE WORDS:  Study designs are two types. Experimental studies and observational studies.  Experimental studies: If our research contains any experiments (on animals etc), then they are called experimental studies.  Observational studies: If the research is without experiment, and just by observing the patients (like how a drug acting on certain group of patients from past 20 years), then it is called Observational studies. PLEASE DON‟T WRITE THESE SIMPLE EXPLANATIONS. THESE ARE JUST FOR YOUR UNDERSTANDING. STUDY DESIGN OBSERVATIONAL EXPERIMENTAL DESCRIPTIVE ANALYTICAL CASE REPORT CASE SERIES CROSS SECTIONAL LONGITUDINAL CASE CONTROL COHORT RCT NON - RCT
PHARMD GURU Page 3 DESCRIPTIVE STUDIES 1) CASE REPORTS:  It is a non experimental method, and is one of the simplest methods in Pharmaco- epidemiology.  Quite often, experts consider it as one of the weakest form of evidence for causation.  Case reports are simply reports of events observed in single patients. A case report describes a single patient who was exposed to a drug and experiences a particular, usually adverse outcome.  Case reports are useful for raising hypothesis about drug effects, which should be tested with more rigorous study designs.  However, in a case report, one cannot know, if the patient reported is either “typically of those with the exposure” or “typically of those with the disease”.  In a case report one cannot usually determine whether the adverse outcome was due to the drug exposure or would have would have happened anyway.  Case reports are hypothesis generating reports. A case report is not ordinarily used to make a report (or) statement on causation of an event.  But it gives a signal that can make others, alert to the possibility of casual association.  The strength of a case report rests on its ability to produce signals. But case reports are very weak in causation. It is to be noted that Pharmacoepidemiology evolved with the publication of case reports in USA in 1960s, mostly by hospital pharmacists & clinical pharmacist. Advantages:  They serve as an alerting mechanism for clinician‟s, investigators and others that a drug (or) group of drugs could produce a given effect.  It prompts clinicians to be aware of the potential problems and to report other such occurrences.
PHARMD GURU Page 4  They may directly lead to hypothesis generation that can guide research.  The most serious adverse drug reactions have been detected by a collection of single case reports. Disadvantages:  Case reports are the weakest form of evidence for causation. It is very rare that a case report can be used to make a statement about causation. 2) CASE SERIES:  Case series, like case reports are observational descriptive studies in pharmaco epidemiology. It is a qualitative (descriptive) non-experimental method and is considered stronger than Case Reports.  Case series are also known as a Clinical series. It is a group or cluster of case reports generated by single/group of clinicians or hospitals or pharmaceutical companies or regulatory agencies like Food and Drug Administration (FDA) or Drugs Controller.  It is a type of medical research study that tracks subjects with a known exposure, such as patients who have received same medicine.  A set of sequential case reports makes a case series. Case series are collections of patients all of whom have a single exposure and whose clinical outcomes are then evaluated and described. The patients can be identified for the case series either based on the exposure or on the outcome.  The case series studies are useful in quantifying the incidence of an adverse reaction and arc generally used for the study of newly licensed or marketed medicines.  The greater the number of common experiences occurred to patients, the stronger will be the signal to support a conclusion. If six patients developed aplastic anemia after administration of the same medications, that can raise a strong suspicion compared to one person developing aplastic anemia.  A classical example of Case Series occurred with Thalidomide induced phocomelia in the early 1960s when same type of malformations was reported in a cluster.