wk 7- prognostic Flashcards
prognosis questions include
P- paint and specific condition relevant to prognosis
I- intervention
O- outcome
T- time
it is common for questions to just include P and O
prognosis hierarchy of evidence
level 1- systematic review of level II studies
level 2- prospective cohort study (0bservational study)
level III-1- not used for a prognostic question?
level III-2 analysis of the prognostic factors among the participants in one group of a RCT (lower on list because of its strict inclusion and exclusion criteria not representing the population)
level III-3 - retrospective cohort study. (incomplete Data risk, selection bias)
Level IV- case series or cohort study where participants are at different stages of the condition or disease
inception cohort is?
group of participants are enrolled in the study at the onset or very early in the progressing of their condition.
where to search for prognostic evidence?
pubmed clinical queries and change category to prognosis
5 year survival means?
% patients surviving 5 years from some point in the course of their disease
case fatality means?
% patients with disease who die of it
disease - specific mortality means?
number of patients per 10,000 or 100,000 population dying of disease
response means?
% patients showing some evidence of improvement following an intervention
remission means?
% patients entering. phase in which disease is no longer detectable
recurrence means?
% patients who have return of disease after a disease-free interval
whats wrong with retrospective cohort studies? 2
- recruitment bias
- systematically miss patients with particular characteristics
appraisal- how can you tell there is a representative and well defined sample of participants?
similarity at the start and all patients or consecutive cases/patients
appraisal- were participants recruited at a common point in the disease/condition?
inception cohort is the best way to avoid this bias
appraisal- was exposure determined accurately (intervention)
look at eligibility criteria and if participants were enrolled into the study but did not undergo completely
appraisal- was follow up sufficiently long and complete?
loss to follow up (5 and 20 rule)
- <5% loss to follow up unlikely to influence results
>20 seriously impacts validity
what is usually used to present prognostic data?
survival curves- showing the likelihood of an event changes over time
how to interpret a survival analysis curve graph
curve can be smooth or square in nature
square means theres less subjects and a drop means 1 person has experienced the outcome
dotted black line shows us the average for 50% of patients
confidence intervals get wider as the number drops lower
evidence to inform practice for prognostic questions 4
-share decision making
-likely clinical course allows for more informed decision making
-able to more effectively discuss options for patients
-must ensure patient understands what you’re saying
what is the reporting standard for observational studies?
STROBE statment
do cohort prognostic studies show prognostic factors that cause of an outcome
no, only establishes prognostic factor is associated with given outcome
how is continuous and dichotomous data reported?
Continuous outcomes measures are usually reported as a mean value at a certain time period. For example, men with aphasia after their first stroke showed an average improvement of 12.3 on the Aphasia Quotient 1 year after stroke.
Dichotomous and ordinal outcomes are usually reported as the proportion of patients who experienced the outcome (that is, the risk of the event) at a particular point in time. For example, among adults over 65 years who present to primary care with back pain, 60% reported persistent disability (Roland-Morris Disability Questionnaire score of ≥4) at 6 months.
what do survival curves show
Survival curves are often used to present prognostic data, and they show how the likelihood of an event changes over time
2 main questions for appraising results?
The two main questions that you need to ask when considering the results of a prognostic study are: (1) how likely are the outcomes over time?; and (2) how precise are the estimates of likelihood?
