Outcome instruments selection WeiChu Chie Preventive Medicine outcome

  • Slides: 27
Download presentation
Outcome/ instruments selection Wei-Chu Chie Preventive Medicine outcome research 1

Outcome/ instruments selection Wei-Chu Chie Preventive Medicine outcome research 1

A review of outcomes – Clinical • Death: binary/Disease: any type/Utilization of care –

A review of outcomes – Clinical • Death: binary/Disease: any type/Utilization of care – Functional/QOL • Discomfort, QOL/Disability – Perceptual • Dissatisfaction/satisfaction, QOL – Financial – Behavioral • true behaviors/self-efficacy/utilization of 2 outcome research care

A review of criteria for good instruments • Precision – free of random error

A review of criteria for good instruments • Precision – free of random error • Accuracy – free of systematic error outcome research 3

Principles of outcome & instrument selection • Outcome and instrument are related • Basic

Principles of outcome & instrument selection • Outcome and instrument are related • Basic principles – goal(s) of the research – nature of outcome – time span of outcome assessment – criteria of good instruments outcome research 4

Endpoints and outcome • An index selected to describe outcome • usually used in

Endpoints and outcome • An index selected to describe outcome • usually used in experimental researches – primary/secondary/tertiary – time to event/clinical/surrogate/behavioral, . . . outcome research 5

Research goal and nature of endpoints • Primary endpoints – of biological or clinical

Research goal and nature of endpoints • Primary endpoints – of biological or clinical importance – form the basis of the objectives of the trial/study – not be highly correlated – sufficient statistical power – relatively few (< 4) outcome research 6

Research goal and nature of endpoints • Secondary endpoints – of biological or clinical

Research goal and nature of endpoints • Secondary endpoints – of biological or clinical importance but less adequate statistical power – potentially important but highly correlated with primary endpoints – address other important but ancillary objectives outcome research 7

Research goal and nature of endpoints • Tertiary endpoints – exploratory – not of

Research goal and nature of endpoints • Tertiary endpoints – exploratory – not of major importance outcome research 8

Time span of outcome assessment • Long-term: event or time to event – mortality

Time span of outcome assessment • Long-term: event or time to event – mortality – morbidity • Mid-term: clinical, QOL • Short-term: behavioral or satisfaction outcome research 9

Long-term outcomes – Time to events (change of status) – events: • mortality/survival (final)

Long-term outcomes – Time to events (change of status) – events: • mortality/survival (final) • recurrence • onset of an expected disease/adverse effect – ‘hard’ endpoints: more objective – two components: • time or person-time • event: binary, clear-cut: outcome research occurred/censored 10

Long-term outcomes • Strengths – objective: ‘hard’ endpoints – accurate and precise – easy

Long-term outcomes • Strengths – objective: ‘hard’ endpoints – accurate and precise – easy to access and measure • Weakness – time consuming – too much simplified/insensitive – too late in prevention outcome research 11

Mid-term outcomes • Clinical symptoms, signs, laboratory findings, … – biochemistry, physiology, … •

Mid-term outcomes • Clinical symptoms, signs, laboratory findings, … – biochemistry, physiology, … • Quality of Life* • Sometimes as surrogate endpoints to ‘time-to-event’ endpoints outcome research 12

Mid-term outcomes • Strengths – less time consuming – more sensitive to treatment/predictors •

Mid-term outcomes • Strengths – less time consuming – more sensitive to treatment/predictors • Weakness – not necessarily predictive to final events – less accurate and precise: somewhat ‘soft’ – more difficult to measure outcome research 13

Short-term outcomes • Behavioral – response to education/counseling, … • Satisfaction – toward treatment

Short-term outcomes • Behavioral – response to education/counseling, … • Satisfaction – toward treatment and disease/health status outcome research 14

Short-term outcomes • Strengths – less time consuming – sensitive to treatments • Weakness

Short-term outcomes • Strengths – less time consuming – sensitive to treatments • Weakness – not necessarily predictive to final events – less accurate and precise: ‘soft’, subjective – more difficult to measure outcome research 15

Special use of QOL • Ever seen/used as – a ‘soft’ endpoint – compensation

Special use of QOL • Ever seen/used as – a ‘soft’ endpoint – compensation of the failure in curative treatments • Current extension of its role – a necessary efficacy index – economic analysis if used with survival: QALY or QAS outcome research 16

QOL • Generic – cross different diseases/condition/population – format: based on definition of health

QOL • Generic – cross different diseases/condition/population – format: based on definition of health • health profile (multi-dimensional questionnaire) • utility (single index or multi-dimensional) – visual analog scale/standard gamble/time-tradeoff – purposes • description/treatment effect/economic outcome research evaluation 17

QOL • Specific – disease/condition/population-specific – format: • extended from generic + specific problems

QOL • Specific – disease/condition/population-specific – format: • extended from generic + specific problems • health profile (multi-dimensional questionnaire) – purposes • description/treatment effect evaluation • not cross-disease transferable outcome research 18

Example • Evaluation of the effect of a diet & exercise education program on

Example • Evaluation of the effect of a diet & exercise education program on patients with CAD – long-term: fatal MI/non-fatal MI – mid-term: serum lipid profile, BMI, QOL – short-term: diet & exercise pattern outcome research 19

A review of criteria for good instruments • Precision: free of random error –

A review of criteria for good instruments • Precision: free of random error – the degree to which a variable has nearly the same value when measured several times – coefficient of variation (C. V. ) – reliability • test-retest • internal consistency • inter- and intra-observer consistency outcome research 20

A review of criteria for good instruments • Accuracy: free of systematic error –

A review of criteria for good instruments • Accuracy: free of systematic error – the degree to which a variable actually represent what it is supposed to represent – validity – with gold standard • sensitivity • specificity • predictive validity outcome research 21

A review of criteria for good instruments • Accuracy: free of systematic error –

A review of criteria for good instruments • Accuracy: free of systematic error – without gold standard • face validity & content validity • criterion-related validity – convergence validity – divergence validity • construct validity outcome research 22

Access to data/instrument selection • Event/time-to-event – primary data: follow-up – secondary data: electronic

Access to data/instrument selection • Event/time-to-event – primary data: follow-up – secondary data: electronic or paper • mortality: national mortality registry • cancer: cancer registry • other special registries • NHI database • hospital records outcome research 23

Access to data/instrument selection • Clinical data – sources • primary: select precise and

Access to data/instrument selection • Clinical data – sources • primary: select precise and accurate clinical instruments • secondary: medical record or laboratory work – format • manual/paper/automaticallygenerated/electronic – QA & QC: good calibration/training outcome research 24

Access to data/instrument selection • QOL/Symptoms/Satisfaction/Behavio r – questionnaire/primarily from the subject • self-design

Access to data/instrument selection • QOL/Symptoms/Satisfaction/Behavio r – questionnaire/primarily from the subject • self-design vs. using existing or translated • translate existing Foreign questionnaire • read validation reports/instructions carefully – observation/use of markers/informants – secondary • utilization of care: from NHI or hospital records outcome research • use existing data base of previous 25

Multiple outcomes/endpoints • Positive side – enrich the results – take care of different

Multiple outcomes/endpoints • Positive side – enrich the results – take care of different aspects/time frames • Negative side – confusing: which one is the most important? – opportunistic: one significant is significant outcome research 26

Putting all information together • Construct a composite index – QALY or QAS –

Putting all information together • Construct a composite index – QALY or QAS – QOL * survival • Develop a time-sequence model – time-dependent predictors eg. weight, cholesterol – path analysis outcome research 27