Level 1 Evidence
Randomized controlled trial (RCT): a study in which patients are randomly assigned to the treatment or control group and are followed prospectively
Level 2 Evidence
Prospective cohort study a study in which patient groups are separated non-randomly by exposure or treatment, with exposure occurring after the initiation of the study
Level 3 Evidence
Retrospective cohort study: a study in which patient groups are separated non-randomly by exposure or treatment, with exposure occurring before the initiation of the study Case-control study: a study in which patient groups are separated by the current presence or absence of disease and examined for the prior exposure of interest
Level 4 Evidence
Case series a report of multiple patients with the same treatment, but no control group or comparison group
Level 5 Evidence
Case report (a report of a single case) Expert opinion Personal observation
In which of the following types of studies can an incidence rate be determined?
A study of patients undergoing total hip arthroplasty has been completed that compares the length of time it takes the patients to walk without aids to their age. What statistical technique should be used to analyze the data?
cohort study definition
groups are separated non-randomly by exposure or treatment
can be level II (prospective) or level III (retrospective)
follows a particular group in relation to an event, studying them at intervals in time
and uses objective outcome criteria.
case control study definition
all the subjects are selected based on whether they
have (cases) or do not have (controls) the disease or outcome of interest.
Case control studies are retrospective as they always look back to see how a certain risk factor may be
different between the two groups.
Type of study to report outcome with RR
Cohort studies follow a group of individuals over time and are optimal for studying the incidence, course, and risk
factors of a disease.
Type of study to report outcome with odds radio?
best wound vac setting
125 mm Hg