Lecture Wednesday 30 March 2005

Shift focus from retrieval to synthesis

Users making consequential decisions

Information systems in augmenative role

130k+ breast cancer articles (MeSH term: "breast neoplasm")
cancer 'cures' often worse than symptoms
beyond age + gender, risk factors don't explain half of breast cancer incidence

desirable properties of a system:
integrate well with work practices


In epidemiology, becasue of the non-experimental design of the studies, we should expect results to be controversial (http://www.hsph.harvard.edu/Organizations/DDIL/gep_PE.html)
risk factors should be skeptically treated in exploring any notion of causality

Cochrane reviews (http://www.cochrane.org/index2.htm)

Are there results Epi studies, RCTs, mixtures?

Conchrane reviews pertain mainly to RCTs:
"The Cochrane Collaboration and the Cochrane Reviewers’ Handbook focus particularly on systematic reviews of randomised controlled trials (RCTs) because they are likely to provide more reliable information than other sources of evidence on the differential effects of alternative forms of healthcare (Kunz 2003). Systematic reviews of other types of evidence can also help those wanting to make better decisions about healthcare, particularly forms of care where RCTs have not been done and may not be possible or appropriate. The basic principles of reviewing research are the same, whatever type of evidence is being reviewed. Although we focus mainly on systematic reviews of RCTs we address issues specific to reviewing other types of evidence when this is relevant. Fuller guidance on such reviews is being developed."
(http://www.cochrane.dk/cochrane/handbook/1_introduction/1_0_introduction.htm)

Cohort studies: (http://servers.medlib.hscbklyn.edu/ebm/2400.htm)
"A Cohort Study is a study in which patients who presently have a certain condition and/or receive a particular treatment are followed over time and compared with another group who are not affected by the condition under investigation.

"For instance, since a randomized controlled study to test the effect of smoking on health would be unethical, a reasonable alternative would be a study that identifies two groups, a group of people who smoke and a group of people who do not, and follows them forward through time to see what health problems they develop.

"Cohort studies are not as reliable as randomized controlled studies, since the two groups may differ in ways other than in the variable under study. For example, if the subjects who smoke tend to have less money than the non-smokers, and thus have less access to health care, that would exaggerate the difference between the two groups.

"The main problem with cohort studies, however, is that they can end up taking a very long time, since the researchers have to wait for the conditions of interest to develop. Physicians are, of course, anxious to have meaningful results as soon as possible, but another disadvantage with long studies is that things tend to change over the course of the study. People die, move away, or develop other conditions, new and promising treatments arise, and so on. Even so, cohort studies are generally preferred to case control studies, since they involve far fewer statistical problems and generally produce more reliable answers. "

More on Epi tests/experimental design:
http://www.vetmed.wsu.edu/courses-jmgay/GlossClinStudy.htm


Concept of "ever drinker"
working in tox labs, dosage was everything


I want to see dimensions that express dosage mean & variance
and clinical experiment OR observational study
use the height of the bar or the shade/intensity of color