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Karteikarten

Week 11

Indah Epidemiology Englisch 29 Karten

Karten in diesem Stapel (29)

  1. 1Intervention studiesClinical trial, experimental study. Aim: to select the best available preventative or therapeutic measures to change the natural history of a disease.
  2. 2Types of intervention studiesTherapeutic (secondary prevention): when someone already has the disease, to see what works. Preventive (primary prevention): prevent initial development of disease
  3. 3Trial TypesTherapeutic Trials, Preventive trials for healthy individuals and Preventive trials for at risk groups
  4. 4Clinical trials vs Community trialsClinical trials: e.g. pharmaceutical agencies or research institute, has a specific criteria. Community; has a more rigid criteria e.g. lives in the same area
  5. 5Efficacy vs. EffectivenessEfficacy; how good a drug is in ideal conditions e.g. clinical trials. Effectiveness; how good a drug works in real conditions e.g. given to a wider population
  6. 6Design of trials - featuresSampling; sample size and composition. Randomisation; divide subjects b/w groups randomly. Stratification; grouping subs according to charac b4 randomisation. Controls; choosing a good control tx. Cross over; switching tx & control grps after a period of time. Placebo; using to mask what tx is being given. Blinding; assessm. by those unaware of the tx group. (single, double, triple)
  7. 7Designing intervention studySelection of study population, allocation of intervention, follow up, maintenance & assessment of compliance & Ascertainment of outcomes.
  8. 8Allocation of study regimesEffect of intervention (tx, procedure or program) should be compared to : another dosage of same drug, another therapy/program, standard medical practice & placebo.
  9. 9Assignment/AllocationBy random allocation so every individual has the same chance of either group. Purpose: to remove selection bias & groups more comparable
  10. 10Other allocation methodsNo controls, historical controls (e.g. changes over time), & simultaneous non-randomised controls
  11. 11Types of clinical trialsRCT, Self controlled designs & cross over designs
  12. 12Cross over studyUses 2 groups (tx & control), after period tx & placebo withdrawn for washout period (where they receive no tx), the groups swap
  13. 13Issues in RCT designaim to achieve valid determination of the comparitive benefit of competing interventions for: Prevention, Screening, Tx & Pt management
  14. 14Content of RCTsPhase I - Clinical pharmacological studies. Phase II - Clinical investigations. Phase III - large scale RCT for effectiveness & safety. Phase IV - Post marketing surveillance
  15. 15RCT outcomeShould have a single outcome. Secondary outcomes can be examined. Outcomes may be; a continuos variable, a dichotomous (2 outcomes) variable, a time to event variable or QOL.
  16. 16Who should participate? Phase IIICriteria should be based on those who: have the potential to benefit, have the ability to demonstrate the outcome, are unlikely to show adverse effects, dont have competing risks, are likely to comply & are easy to follow up
  17. 17Who should participate? Phase IVRecruit a more diverse range of subjects = enhanced external validity & makes the results a better reflection of real life.
  18. 18Sample sizeFor Phase I and Phase II = small. Phase III = larger and Phase IV = even larger
  19. 19BindingTo minimalise observation bias. 3 levels: subject, observer & analyst
  20. 20Time to event studiesPowerful and flexible when outcome variable is appropriate. Suited to long term trials of preventive and screening programs
  21. 21Group randomised studiesClusters of ppl randomised - suited to community intervention studies. Application: behavioural/lifestyle interventions, infectious diseases interventions, screening trials, health services research. Reduce data collection costs & need larger sample size
  22. 22Community intervention trialsDefined geographically or socially determined. Advantages: feasibility of delivery of intervention, avoiding contamination between subjects & using site specific resources for delivery
  23. 23Advantages of RCTsRandomisation balances prognostic factors, Detailed info can be collected on baseline & subsequent charac of subs, Dose lvls pre determined, Blinding reduces bias in assessment of outcome, Assumptions for stat tests met
  24. 24Disadvantages of RCTsSubject exclusion may limit generalizability of findings to other pts, long period of time req to reach conclusion, large no. of subs may be req, expensive, ethical issues & lack of compliance w/tx
  25. 25Non-complianceRefusal to take part int he study
  26. 26Ethical considerationsDont give something harmful, dont deny something beneficial, informed consent & the participant decides.
  27. 27Exp & cohort studies- analysis & interpretationsimilar analysis, compare risk of the outcome of interest in the exposed (tx grp) and those in the comparison group
  28. 28AnalysisRR, OR
  29. 29Issues in interpretationBias potential: from non response, in assessment of outcome, loss to follow up and analytical

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Beschreibung
Epidemiology Karteikarten am Week 11, erstellt von Indah am 17/10/2013.
Erstellt von
Indah
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