Understanding medical research
Thomas Abraham
Three areas of health and medical reporting
Medicine Public health Health policy
Medical Reporting
By the end of this class, you should Know the different sources of medical
news Be familiar with the main medical
journals Know the different categories of
medical research studies Have an understanding of how to turn
a study into news
Where does medical news come from?
1. Medical journals
2. Scientific conferences3. Press conferences to announce findings4. Reports from organizations like the WHO
Journal articles are regarded as the most reliable source, because the findings have been peer reviewed
The most prestigious:The LancetThe New England Journal of Medicine (NEJM)British Medical Journal (BMJ)Journal of the American Medical Association (JAMA)ScienceNature
Press releaseswww.eurekalert.org BMJ press releaseshttp://group.bmj.com/group/media/bmj-press-releasesJAMA press releases:http://pubs.ama-assn.org/media/pastreleases.dtl
How do journals work?
Researchers write up their findings in a paper and submit to a journal, which then puts it through a process of peer review
Peer review=other experts in the field review the paper and asses it
Peer review is not perfect, but there is not a better system at present (the case of Hwang Woo-suk and the cloning of human stem cells)
The structure of a journal article-IMRAD
Abstract: sums up study Introduction- Why is this study being
done? Methods- How did you do it? Results- What did you find? Discussion- What is its importance?
What reporters need to ask
Is this news? How solid is the study and the
evidence? Will people be able to use, or benefit
from this study? Who funded the research?
Types of study
Observational
Experimental
Meta studies
Types of studies
Observational : Where researchers observe groups of people, gathers data, but do not make any kind of intervention
eg: a study of pollution on respiratory disease which observes people in a polluted part of town, measures surrounding air pollution, and looks at the incidence of disease in this group.
Experimental: Where the researchers intervene in some way, for example by providing a new treatment, and then measures the results, and compares with an older treatment.
Metastudy: Looks at a large number of published studies on a particular topic, and looks at the overall conclusion
Different studies answer different questions
Experimental studies, such as clinical trials are best suited to answer questions of cause and effect ( including is the effect of drug A better than drug B)
Observational studies tend to show statistical associations, rather than cause and effect.
Observational studies
Cross sectional studies
Case-control studies
Cohort studies
Observational studies
Cross sectional studies measure, or survey data at a point in time)
Eg: Opinion survey of nurses in Hong Kong about H1N1 vaccination
Eg: Prevalence of obesity among teenagers
They describe a situation at a point of time, but does not analyse cause and effect
Observational studies
Analytical studies (seek to suggest possible reasons for occurrence of a disease or population)
a) Case control studies-Patients with a particular disease or condition are matched with a similar group of people without the disease, and then data is collected from both groups about past exposure or behaviour
Bradford Hill and Doll’s 1950 study
Two groups of patients admitted to London hospitals were studied
649 lung cancer patients( cases) 649 patients without cancer (controls) Cases and controls matched for age, sex Aim of the study: “whether patients with
carcinoma of the lung differed materially from other persons in respect of their smoking habits”
649lung
cancer
649no lung cancer
Question to be answered: is smoking the difference between these two groups?
Cases Controls
649lung
cancer
649 no lung cancer
647Smokers(99.7%)
622Smokers(95.8%)
Cases Controls
649lung
cancer
649 no lung cancer
2 Non Smokers(0.3%)
27 Non Smokers(4.2%)
Cases Controls
lung cancer
no lung cancer
total
smokers 647 2 649
non smokers
622 27 649
Lung cancer
No lung cancer
Smoker 99.6% 0.30%
Non smoker
95.83% 4.16%
Proportion of heavy smokers greater in cancer patients
Proportion of lighter smokers lessConclusion: “it must be concluded that
there is a real association between carcinoma of the lung and smoking”
Some weaknesses of case control studies
Relies on past or behaviour – therefore often relies on memory, can lead to biases in data
Observational studies
Cohort studies- Two or more groups of people are chosen on the basis of differences in their behaviour, or exposure to a particular agent and followed up over a period of time to see the differences in outcome between the groups
Doll and Bradford Hill’s study Studied 40,000 British doctors over 10, 20
and 40 years Divided them into 4 groups non smokers,
light, moderate and heavy smokers Results showed substantial differences in
lung cancer mortality between smokers and non smokers
Showed heavier smokers had a greater chance of developing cancer than the other groups ( dose response relationship)
Some limitations of cohort studies
Can take a long time People can drop out Not an absolute proof of causation
Experimental studies- Randomised controlled trial (RCT)
Gold standard of causality Used to evaluate new treatments Subjects are randomly allocated to
intervention (gets new treatment and control( does not get new treatment) groups
Both groups should be as similar as possible
Double blind= neither subject nor researchers know who is getting what
Meta Studies
Looks the results of a wide range of published studies; regarded as high evidence value
Evaluating papers
Is it still at the animal or laboratory stage, or human stage?
Where published? peer reviewed journal, scientific meeting or press release/conference?
How big were the numbers tested? How relevant are the findings-is it of
immediate benefit for people What will it cost? Conflicts of interest
How big were the numbers tested? How relevant are the findings-is it of
immediate benefit for people What will it cost?
Exercise
Read the article- Is it newsworthy?- Is it a good study ( ie large numbers,
well designed)?- Published in a peer reviewed journal?- Will this information benefit patients?- If it is a new treatment, what cost?- Conflicts of interest
Writing
What’s the lead? What additional material do you need? What do you need to explain?
Deadlines
Feb 28: First Story March 15: Book Review March 28: Second Story April 17: Third StoryOnline courses to be completed by Feb 21 Malaria Feb 28: TB March 8: HIV