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I – Investigated condition (e.g. intervention, exposure, risk/ prognostic factor, or test result) C – Comparison condition (e.g. intervention, exposure, risk/ prognostic factor, or test result respectively) O – Outcome(s) (e.g. symptom, syndrome, or disease of interest) Alternatives such as SPICE and PECO (among many others) can also be used.
The prospective study is important for research on the etiology of diseases and disorders. The distinguishing feature of a prospective cohort study is that at the time the investigators begin enrolling subjects and collecting baseline exposure information, none of the subjects have developed any of the outcomes of interest. [ 2 ]
One point is assigned for each of the following risk factors: [citation needed] Age greater than 60 years; Stage III or IV disease; Elevated serum LDH; ECOG/Zubrod performance status of 2, 3, or 4; More than 1 extranodal site; The sum of the points allotted correlates with the following risk groups: Low risk (0-1 points) - 5-year survival of 73%
The group exposed to treatment (left) has half the risk (RR = 4/8 = 0.5) of an adverse outcome (black) compared to the unexposed group (right). The relative risk (RR) or risk ratio is the ratio of the probability of an outcome in an exposed group to the probability of an outcome in an unexposed group.
Stratification of clinical trials is the partitioning of subjects and results by a factor other than the treatment given. Stratification can be used to ensure equal allocation of subgroups of participants to each experimental condition. This may be done by gender, age, or other demographic factors.
Hazard ratios do not reflect a time unit of the study. The difference between hazard-based and time-based measures is akin to the difference between the odds of winning a race and the margin of victory. [3] When a study reports one hazard ratio per time period, it is assumed that difference between groups was proportional.
A retrospective study, on the other hand, looks backwards and examines exposures to suspected risk or protection factors in relation to an outcome that is established at the start of the study. Many valuable case–control studies, such as Lane and Claypon's 1926 investigation of risk factors for breast cancer, were retrospective investigations.
One example of a prognostic biomarkers in clinical research, is the use of mutated PIK3CA in the study of metastatic breast cancer. As illustrated by the graph, the mutation is prognostic since its presence in the patient endure the same outcome regardless of the treatment method used. Women who had the PIK3CA mutation before treatment, had the ...