PMHP Flashcards
Critical appraisal
The process of assessing and interpreting evidence through the systematic consideration of its validity, relevance and results
Observational uncontrolled studies
Researchers watch what happens to a group of people
A group of patients has disease A and is treated with drug X, the researcher observes how many get better
How believable? Control group required because humans can get better without drugs
Controlled studies
Cohort or case control
Researchers observe what happens to people in different situations without intervening
Randomised controlled trials
Patients randomly split into 2 or more groups, one group gets intervention, the other gets placebo
Any differences at follow up are caused by intervention
Case report/case series
A report on a single patient or series of patients with an outcome of interest
No control group
Used to identify new disease outcome and hypothesis generation
Disadvantages - cannot demonstrate valid statistical associations, lack of control group
Cross sectional study
Observation of a defined population at a single point in time or time interval
Exposure and outcome are determined at the same time
Used for estimating prevalence of disease, investigating potential risk factors
Disadvantages are causality and confounding
Case control study
Study of people with a disease and suitable control group without the disease
Looks back in time at exposure to a particular risk factor in both groups
Used for looking at potential disease causes
Disadvantages - confounding, recall/selection bias, selection of controls, time relationships
Cohort study
Establish a group of individuals in population and measure exposures
Follow up over a period of time
Identify those that develop a disease
Used for - estimating incidence, investigating disease causes, determining prognosis, timing and direction of events
Disadvantages - controls difficult to identify, confounding, blinding is difficult, for rare diseases - need large samples, expensive and time consuming
Randomised control trials
Sometimes referred to as clinical trials
GOLD STANDARD for effectiveness and efficacy
Provides strongest evidence on effectiveness of treatments
PICO
Population
Intervention
Comparison
Outcome
Was there a focussed question?
CASP
Critical Appraisal Skills Programme
A tool used to determine whether the findings of a study are valid - gives key questions to be asked
Risk difference
Risk in trial group as % - risk in control group as % = Risk difference
Number needed to treat
The number of patients you would need to treat to prevent one patient from developing the disease/condition/outcome
1/ absolute risk difference
Consort
25 item checklist used to identify problems arising from conducting randomised control trials
Can be used to help design a study and to critically appraise a study
