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aarista's version from 2016-06-23 17:09

core ethical principles

Question Answer
autonomyobligation to respect pts as individuals, to create conditions necessary for autonomous choice (informed consent), and to honor their preference in accepting health care or not
beneficencephysicians have a special ethical (fiduciary) duty to act in the pt's best interest. may conflict w autonomy (an informed pt has right to decide) or what is best for society (eg. mandatory TB treatment). traditionally, pt's interest supersedes
nonmaleficence"do no harm" must be balanced against beneficence; if the benefits outweigh the risks, a pt may make an informed decision to proceed (most surgeries and medications fall into this category)
justiceto treat persons fairly and equitably. this does not always imply equally (eg. triage)
memorize

bias and study errors

typedefinitionexamplesstrategy to reduce bias
selection biaserror in assigning subjects to study group resulting in an unrepresentative sample. most commonly a sampling biasBerkson bias - study pop from hospital less healthy than gen pop
Healthy worker effect - study pop healthier than the gen pop
Non-response bias - participating subjects differ from non-respondents in meaningful ways
randomization, ensure the choice of the right comparison/reference group
recall biasawareness of disorder alters recall by subjects; common in retrospective studies (case-control)pts w dz recall exposure after learning of similar casesdecrease time from exposure to follow-up
measurement biasinformation is gathered in a systematically distorted mannerassociation btw HPV and cervical cancer not observed when using non-standardized classificationsuse objective, standardized and previously tested methods of data collection that are planned ahead of time
procedure biassubjects in different groups are not treated the samepts in tx group spend more time in highly specialized hospital unitsblinding, use of placebo reduce influence of participants and researchers and interpretation of outcomes as neither are aware of group allocation
observer-expectancy biasresearcher's belief in the efficacy of a treatment changes outcome of that treatment (aka Pygmalion effect; self-fulfilling prophecy)if observer expects tx group to show signs of recovery, then he is more likely to document positive outcomesblinding, use of placebo reduce influence of participants and researchers and interpretation of outcomes as neither are aware of group allocation
confounding biaswhen a factor is related to both the exposure and outcome, but not on the casual pathway > factor distorts or confuses effect of exposure on outcomepulmonary dz is more common in coal workers than gen pop; however, ppl who work in coal mines also smoke more than gen pop-multiple/repeated studies
-crossover studies (subjects act as their own controls)
-matching (pts w/ similar characteristics in both tx and control groups)
-restriction
-randomization
lead-time biasearly detection is confused w/ increased survivalearly detection makes it seems as though survival has increased, but the natural history of the dz has not changedmeasure "back-end" survival (adjust survival according to severity of dz at time of diagnosis)
memorize