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 journals2. 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 studiesCross sectional studies measure, or

survey data at a point in time)Eg: Opinion survey of nurses in Hong

Kong about H1N1 vaccinationEg: Prevalence of obesity among

teenagers They describe a situation at a point of

time, but does not analyse cause and effect

Observational studiesAnalytical 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 studiesCohort 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