RESS revision Flashcards
4 steps in clinical audit cycle
1 = preparation and planning 2 = measuring performance 3 = implementing change 4 = sustaining improvement (including re-audit)
what does a service evaluation do
evaluates current service/proposed practice - intention of generating info to inform local decision-making
research cycle 8 steps
- identifying topics
- commissioning
- designing research
- managing research
- data collection
- analysis and interpretation
- dissemination
- evaluation
is NICE non governmental
yes
who funds NICE
department of health
who appoints board and chair of NICE
secretary of state
8 of NICE’s core principles
scientific rigour inclusiveness transparency independence challenge review support for implementation timeliness
what are NICE quality standards (not the same as NICE guidelines)
prioritised, concise set of statements (6-8) with associated measurable indicators, chosen and adapted from clinical guideline recommendation s
what do NICE guideline and development groups (GDGs) do
review and make judgements based on evidence and make recommendations - respond to consultation comments
what do NICE national collaborating centres (NCCs) do
convene GDGs, provide technical input to facilitate GDG, draft guidlines
4 things making up a GDG
chair (clinical leader)
clinical and academic experts
patients, carers, lay members
NCC technical team
equal status
what happens if an exposure occurs after an outcome
it is a consequence of it (descendant)
what are covariates
variables that might cause either the exposure and/or outcome
3 types of covariates
confounder
mediator
competing exposure
what does a confounder cause
both outcome and exposure
what does a mediator cause
outcome, and caused by exposure
what does a competing exposure cause
outcome only
why do we adjust for confounders
create a pseudo-causal path between outcome and exposure = generates statistical relationship between them even when none exists
why do we NOT adjust for mediators
part of the causal path between outcome and exposure - risk ‘adjusting out’ this pathway
why MIGHT we adjust for competing exposures
may cause a substantial amount of the variation in the exposure
4 types of variable which are necessary
exposure
outcome
measurable/available confounders
measurable/available competing exposures
are mediators necessary variables
no
example of a prospective study
cohort - measure/record variables during the study period with the outcome subsequently measured
example of a retrospective study
case-control - record/measure outcome then look back to find exposure and covariates
are cross-sectional studies prospective or retrospective
both
what is a latent variable
missing variable
what is target population
total finite population of those we wish to apply study results and from which any study sample is drawn
what is study sample
people/contexts from WITHIN the target population selected for analysis
what is complete sample
entire study population
what is unstratified random/probability sample
every member of target population has same chance of being sampled
what is stratified random/probability sample
randomly sample from target population within strata
what is quota sampling
sample taken from stratified population until pre-assigned quota in each stratum is represented
is quota sampling random
NO
what is cluster sampling
when ‘natural’ but homogenous groupings are evident in population e.g. regions of the UK - simple random sampling used within each cluster
what is the odds ratio if there is NO EFFECT
1
how to use confidence interval and OR to see if effect is genuine
if 95% Cl round the OR does NOT include 1 = genuine
how to improve OR confidence interval
increase sample size - OR stays same but CI increases to above 1
what STATA command is used to build linear models/regressions
regress command
how to use STATA regress command if data is categorical
use same regress command but precede ‘regress’ with ‘xi’ then indicate which variables are categorical by putting ‘i’ in front of their name
e.g. xi: regress weight i.sex
2 types of categorical data
nominal (names etc)
ordinal (scale)
no numerical value
how to make ordinal data numerical
rank scale to each category - but will still be classed as categorical
type of analysis for continuous outcome data
multivariable linear regression analyses
type of analysis for binary outcome data
multivariable logistics regression analyses
what is model misspecification
incorrectly specified multivariable regression model in terms of:
- non linear relationships
- omitting important variables e.g. confounding bias
- overadjustment
- transformation of variables e.g. categorising continuous data
when does heterogeneity bias (group difference bias) occur
natural group structures in data and there are differences in the groups that are correlated with the study variable
how many authors used before ‘et al’
6/7
what is the Likert scale (example of ordinal data)
strongly disagree, disagree … strongly agree
what type of data is age
numerical continuous - but often grouped as discrete
what is relative frequency
percentage of total frequency accounted for by particular variables
how to calculate incidence rate
number of new cases occurring in set time / number of people at risk in set time
epidemiological triad
time
person
place
how to calculate mortality rate
number of people who die from disease in period / number of people who die in period of all causes
how to calculate case fatality
number of people who die from a disease in period / number of people with the disease
how to calculate OR
odds for disease of exposed group / odds of disease of unexposed group
when can ORs be used in RCTs
when the RCT is dichotomous
what are dichotomous variables
variable takes 1 of 2 forms that are completely different e.g. dead or alive
type of data for histograms
numerical continuous
measure of distribution in non-normally distributed data
median and IQR (so isnt affected by outliers)
what is standard error a measure of
precision - how reliable the sample population mean is from that of the population
when is correlation the appropriate statistical analysis
when both the outcome and exposure are numerical
appropriate statistical analysis for if the outcome is numerical and the exposure is categorical (independent groups)
T test or Mann-Whitney test
what is an inductive hypothesis
hypothesis proposed after analysis - explains why two sets of info are related to one another
what is a deductive hypothesis
proposed before analysis - think that at least 2 variables are related
what does adding an asterisk to the end of a word mean when refining a search
truncated ending where alternative ending would be accepted
what are boolean operators
to refine searches e.g. AND, OR, NOT
what type of study is a census
cross-sectional - looks at entire population at defined time assessing prevalence
what is Ansecomb’s quartet
4 sets of data with same statistical properties which look very different when displayed graphically
what is responsiveness
whether a measure can detect real change (over time)
what is type 1 error
incorrect rejection of a true NULL hypothesis (false positive for alternative)
what is type 2 error
failure to reject a false null hypothesis (false negative for alternative)
what is chi squared used for
determine association between categorical variables
how is standard error calculated
standard deviation / square root of sample size
what is interval sampling
taking samples at set intervals e.g. drugs company take a sample of every 100th drug etc
what phase of a clinical trial assesses effectiveness and dosages of drugs on a few hundred patients WITH the disease?
phase II
what is a systematic review
mini reports that are peer reviewed - focus on specific topic
what is a consensus study
consensus statement developed by professionals via a group consensus process that is intended to advance health professional and/or public understanding of a targeted health problem
how to calculate risk
risk = number of new cases / number at risk
in what type of study do you use a risk ratio
cohort - used to find risk factors (exposures) of disease
what type of study to use OR
case-control study or RCT
what is relative risk reduction
RRR = 100-RR - i.e. the difference the new treatment makes to the condition (compared to old/untreated group)
range of values of risk
0-1
correlation coefficient used for normally distributed data
Pearson correlation coefficient (r) -1 to 1
correlation coefficient used for not normally distributed data, when 1 or both of the variables are ordinal, or when the sample size is small
Spearman’s
do larger or smaller studies have a larger confidence interval
smaller studies = large CI
what is opportunity cost
value of something when a particular course of action is chosen - what you must forgo in order to get something
benefit foregone from not using the same resources in the next best activity
when have you made the wrong choice in opportunity cost
if it is greater than the value of what you choose - should aim to minimise the opportunity cost of choices
what is economic evaluation
comparison of 2+ alternative courses of action in terms of their costs and their outcomes
2 types of efficiency
technical efficiency
allocative efficiency
what is technical efficiency
meeting a given objective at least cost
what is allocative efficiency
producing the output (supply) that matches consumer want (demand) - is an activity worthwhile?
2 things marginal analysis involves
comparing:
- the benefit from that next step (Marginal Benefit) with
- the cost of taking the next step (Marginal Cost)
NOT interested in average cost and benefit
type of cost analysis when we want to compare alternatives WITHIN a condition
cost effectiveness analysis - benefits measured in terms of standard clinical outcome e.g. change in blood pressure
3 types of cost analysis when we want to compare ACROSS conditions
- cost effectiveness analysis (also considers life years gained)
- cost utility analysis (considers both quality and quantity of life)
- cost benefit analysis (considers resource use and health benefits in monetary terms)
what is the Incremental Cost Effectiveness Ratio (ICER)
expected cost per additional unit of health produced by a new intervention compared to current practice
what is the cost effectiveness threshold
maximum amount the health service will pay per unit of health gained - represents maximum opportunity cost consistent with improving population by introducing a new intervention
NICE threshold for cost effectiveness per QALY gained
£20-30k
what is option appraisal
process for identifying, describing and evaluating alternative methods (options) of achieving an agreed objective
hierarchy of evidence top to bottom
meta-analysis systematic review critically appraised topic RCTs cohort studies case-controlled studies/case series/reports background info/expert opinion
what is a case control study
select participants on basis of their outcome and works back to exposure = cheap, bias
what is a cohort study
longitudinal study following group of people over time, selects participants before the outcome but no control over exposure
what does a service evaluation do
evaluates a current service/proposed practice
difference between audit and service evaluation
audit = does it reach a standard (practice against target)
service evaluation = what standard does/might this achieve (current practice)
what does an audit-cum-service evaluation examine
whether variation in practice may cause variation in compliance - variation in compliance may cause variation in benefit?
what is response bias
what interview wants/gets
what is prestige bias
what appears favourable
what is over adjustment bias
controlling for an intermediate variable or mediator in multivariable regression analysis
what is multicollinearity
when there are strong associations or correlations among covariates in a multivariable regression model
what is pharmacodynamics
what the drug does to the body
what is pharmacokinetics
what the body does to the drug
what does ADME stand for
absorption
distribution
metabolism
elimination
for pharmacokinetics
