Outcome/ instruments selection

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

2. 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 care outcome research

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

4. 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

5. 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

6. 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

7. 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

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

9. 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

10. 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: occurred/censored outcome research

11. 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

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

13. 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

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

15. 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

16. 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

17. 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-trade-off • purposes • description/treatment effect/economic evaluation • cross disease/condition … transferable outcome research

18. 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

19. 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

20. 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

21. 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

22. 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

23. 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

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

25. Access to data/instrument selection • QOL/Symptoms/Satisfaction/Behavior • 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 • use existing data base of previous researches outcome research

26. 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

27. 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