Study Designs - CEBM

 

case series study design

In a retrospective study, the distribution of the disease outcomes (i.e. how many are ill, who is ill, how ill they are etc.) is known at the beginning of the study period. By comparison, case-control studies take a representative group of subjects, and consider known outcomes in that group, and will, by dint of study design, and careful choice. Case-series is a descriptive study design and as the name suggests, its just a series of cases of any particular disease or disease discrepancy that one might observe in one's clinical practice. Aug 22,  · A retrospective case-control uses these two groups and looks back to the past for data and possible risk factors. A matched case-control study chooses controls based on some matching factor, like age, weight or severity of disease. Retrospective Case Series. A case-series is just a series of cases.


Understanding Research Study Designs | Health Sciences Libraries


This short article gives a brief guide to the different study types and a comparison of the advantages and disadvantages. See also Levels of Evidence. Figure 1 shows the tree of possible designs, branching into subgroups of study designs by whether the studies are descriptive or analytic and by whether the analytic studies are experimental or observational.

The list is not completely exhaustive but covers most basics designs. Figure: Tree of different types of studies Q1, 2, and 3 refer to the three questions below. Our first distinction is whether the study is analytic or case series study design. A non-analytic or descriptive study does not try to quantify the relationship but tries to give us a picture of what is happening in a population, e. Descriptive studies include case reports, case-series, qualitative studies and surveys cross-sectional studies, which measure the frequency of several factors, and hence the size of the problem.

An analytic study attempts to quantify the relationship between two factors, that is, the effect of an intervention I or exposure E on an outcome O. To quantify the effect we will need to know the rate of outcomes in a comparison C group as well as the intervention or exposed group. Whether the researcher actively changes a factor or imposes uses an intervention determines whether the study is considered to be observational passive involvement of researcheror experimental active involvement of researcher.

In experimental studies, case series study design, the researcher manipulates the exposure, case series study design, that is he or she allocates subjects to the intervention or exposure group.

Experimental studies, or randomised controlled trials RCTsare similar to experiments in other areas of science. That is, subjects are allocated to two or more groups to receive an intervention or exposure and then followed up under carefully controlled conditions. Such studies controlled trials, particularly if randomised and blinded, have the potential to control for most of the biases that can occur in scientific studies but whether this actually occurs depends on the quality of the study design and implementation.

In analytic observational studies, the researcher simply measures the exposure or treatments of the groups. These studies all include matched groups of subjects and assess of associations between exposures and outcomes.

Observational studies investigate and record exposures such as interventions or risk factors and observe outcomes such as disease as they occur. Such studies may be purely descriptive or more analytical. We should finally note that studies can incorporate several design case series study design. For example, a the control arm of a randomised trial may also be used as a cohort study; and the baseline measures case series study design a cohort study may be used as a cross-sectional study.

The type of study can generally be worked at by looking at three issues as per the Tree of design in Figure 1 :. For observational study the main types will then depend on the timing of the measurement of outcome, so our third question is:. Best for study the effect of an intervention.

A controlled trial where each study participant has both therapies, e, case series study design. Only relevant if the outcome is reversible with time, e. Data are obtained from groups who have been exposed, or not exposed, to the new technology or factor of interest eg from databases. No allocation of exposure is made by the researcher. Best for study the effect of predictive risk factors on an outcome, case series study design.

Patients with a certain outcome or disease and an appropriate group of controls without the outcome or disease are selected usually with careful consideration of appropriate choice of controls, matching, etc and then information is obtained on whether the subjects have been exposed to the factor under investigation.

A study that examines the relationship between diseases or other health-related characteristics and other variables of interest as they exist in a defined population at one particular time ie exposure and outcomes are both measured at the same time. Best for quantifying the prevalence of a disease or risk factor, and for quantifying the accuracy of a diagnostic test.

 

How to design a good case series.

 

case series study design

 

Case-series is a descriptive study design and as the name suggests, its just a series of cases of any particular disease or disease discrepancy that one might observe in one's clinical practice. Kooistra B(1), Dijkman B, Einhorn TA, Bhandari M. Author information: (1)Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Wellington Street North, Suite , Hamilton, ON L8L 2X2, Canada. A case series is a descriptive study that follows a group of patients who have a Cited by: Jul 17,  · Distinguishing cohort studies from case series is difficult. We propose a conceptualization of cohort studies in systematic reviews of comparative studies. The main aim of this conceptualization is to clarify the distinction between cohort studies and case series. We discuss the potential impact of the proposed conceptualization on the body of evidence and mihssiowas.gq by: