KnowledgeKnowledgeWhy bother?Why bother?

Alan, Gavin and NeilAlan, Gavin and Neil

Today’s Aims and Today’s Aims and ObjectivesObjectives• To initially make you feel a bit uncomfortableTo initially make you feel a bit uncomfortable

• To make you think and get your brain’s cogs To make you think and get your brain’s cogs whirringwhirring

• To (hopefully!) leave you feeling slightly To (hopefully!) leave you feeling slightly better, and equipped with some practical tips better, and equipped with some practical tips that will help you in the exam, and your that will help you in the exam, and your medical careermedical career

Medicine is an ocean of Medicine is an ocean of informationinformation

How do we keep ourselves from How do we keep ourselves from drowning in the continuous flow of drowning in the continuous flow of information poured upon us in the information poured upon us in the form of journals, papers, textbooks, form of journals, papers, textbooks, courses etc. ?courses etc. ?

Discuss as a group – possible Discuss as a group – possible strategies to keep updatedstrategies to keep updated

Some Practical TipsSome Practical Tips

• You don’t have to know everythingYou don’t have to know everything

• Limit yourself to a small number of Limit yourself to a small number of relevant journals e.g. BMJ and BJGPrelevant journals e.g. BMJ and BJGP

• Scan the contents, read the Scan the contents, read the abstracts/conclusions of papers, then abstracts/conclusions of papers, then go back in more detail later if go back in more detail later if necessary/relevantnecessary/relevant

Some Practical TipsSome Practical Tips

• Do little and oftenDo little and often

• Try to set realistic goals Try to set realistic goals

• Try to learn around patients – easier Try to learn around patients – easier to retain/recall infoto retain/recall info

• Sign up to GPnotebook tracker (or Sign up to GPnotebook tracker (or similar) – keeps a record of your similar) – keeps a record of your learning – good for PDPlearning – good for PDP

The truth, the whole truth, The truth, the whole truth, and nothing but the truth?and nothing but the truth?

Dismantling the Dismantling the misinformation in research misinformation in research

paperspapers

Why do we need to appraise Why do we need to appraise research ourselves?research ourselves?• Don’t believe what you are told by anyone Don’t believe what you are told by anyone

(including me)(including me)– Spinning statistics is an industry standard:Spinning statistics is an industry standard:

• Scientists do it to get papers publishedScientists do it to get papers published• Governments do it to minimise expenditureGovernments do it to minimise expenditure• Big Pharma does it to get you to prescribe their drugsBig Pharma does it to get you to prescribe their drugs

• Its important to know what you need to knowIts important to know what you need to know– Too much exists out there to read everythingToo much exists out there to read everything– Discarding the rubbish is an important skillDiscarding the rubbish is an important skill– In an information world, you are going to be relied In an information world, you are going to be relied

on more often to give patients advice (in effect on more often to give patients advice (in effect appraise their evidence)appraise their evidence)

Lies, damn lies and Lies, damn lies and StatisticsStatistics• You dont have to be able to do statistics You dont have to be able to do statistics

to read a paper insightfullyto read a paper insightfully

• There are a few key questions to ask There are a few key questions to ask about any research paperabout any research paper– Why was it done?Why was it done?– How was it done?How was it done?– What haven’t they told you?What haven’t they told you?– Do the results support the claims of the Do the results support the claims of the

authors?authors?

Its all relative, innit?Its all relative, innit?

• What does a Relative Risk mean? An exampleWhat does a Relative Risk mean? An example– Relative risk of coffee drinkers versus tea Relative risk of coffee drinkers versus tea

drinkers acquiring vCJD =0.70 (95% CI 0. 68 - drinkers acquiring vCJD =0.70 (95% CI 0. 68 - 0.72) (ref 1)0.72) (ref 1)

– In plain English, I estimate coffee drinkers are In plain English, I estimate coffee drinkers are 30% less likely to acquire vCJD than tea drinkers.30% less likely to acquire vCJD than tea drinkers.

– My margin of error in this estimate lies between My margin of error in this estimate lies between 24-30% less likely to acquire vCJD (Im 95%24-30% less likely to acquire vCJD (Im 95% confident of this)confident of this)

– How would NESCAFE spin this information?How would NESCAFE spin this information?

Its absolutely nothing….Its absolutely nothing….

• It’s ABSOLUTE RISK what matters It’s ABSOLUTE RISK what matters – If risk of vCJD is 1 in 10 million for tea drinkers, and If risk of vCJD is 1 in 10 million for tea drinkers, and

1 in 7 million for coffee drinkers, would you really 1 in 7 million for coffee drinkers, would you really advocate every patient switching to coffee?advocate every patient switching to coffee?

– What if it was 1 in 10 tea drinkers, and 1 in 7 coffee What if it was 1 in 10 tea drinkers, and 1 in 7 coffee drinkers?drinkers?

– In both, the relative risk reduction is the same In both, the relative risk reduction is the same (30%), but the absolute risk reduction is very (30%), but the absolute risk reduction is very differentdifferent

Absolute riskAbsolute risk

• Coffee: Coffee: 1 in 10 million 1 in 10 million = 0.000000010= 0.000000010

• Tea:Tea: 1 in 7 million 1 in 7 million = 0.000000014= 0.000000014

• The absolute risk reduction by switching The absolute risk reduction by switching from tea to coffee is the difference in rates from tea to coffee is the difference in rates = 0.000000004= 0.000000004

• How can we translate this into a meaningful How can we translate this into a meaningful figure for a patient to understand?figure for a patient to understand?

Numbers needed to treat Numbers needed to treat (NNT) (NNT) • This is the most valuable tool you have at This is the most valuable tool you have at

your disposal for making sense of statisticsyour disposal for making sense of statistics

• NNT = 1/absolute risk reductionNNT = 1/absolute risk reduction

• In this example, it is the number of patients In this example, it is the number of patients you need to switch from drinking tea to you need to switch from drinking tea to coffee to prevent 1 additional case of vCJDcoffee to prevent 1 additional case of vCJD

NNT = 250,000,000 (or the whole US NNT = 250,000,000 (or the whole US population)population)

vCJD referencevCJD reference

A multi-centre nested case-control study of A multi-centre nested case-control study of the effect of beverage consumption on the effect of beverage consumption on vCJD risk: analysis from the NESCAFE vCJD risk: analysis from the NESCAFE cohort study.cohort study.

J. Swallow and P. Spitt (2006). Swedish J. Swallow and P. Spitt (2006). Swedish Journal of Epidemiology, Journal of Epidemiology, 4343 69-99. 69-99.

And if you swallowed that, you will swallow And if you swallowed that, you will swallow anything!anything!

Part 1 Take home messagePart 1 Take home message

• Beware studies that sell their Beware studies that sell their message on relative risk reductions message on relative risk reductions or improvementsor improvements

• Always try to determine what the Always try to determine what the absolute risk difference isabsolute risk difference is

• Convert this to NNT for a meaningful Convert this to NNT for a meaningful value you can explain to patients (or value you can explain to patients (or yourself)yourself)

Small group workSmall group work

• Split into 4 groupsSplit into 4 groups– ‘‘Pharmaceutical reps’Pharmaceutical reps’– ‘‘PCT pharmacy commissioners’PCT pharmacy commissioners’– ‘‘GPs’GPs’– ‘‘Patients’ (this is the easy job!)Patients’ (this is the easy job!)

• Look at the abstract of this paper on Look at the abstract of this paper on Clopidogrel versus Aspirin, published Clopidogrel versus Aspirin, published in in The LancetThe Lancet, and follow the briefing , and follow the briefing notes for each groupnotes for each group

You have 15 minsYou have 15 mins

• Work in groups to produce an Work in groups to produce an argument for your case, and nominate argument for your case, and nominate a spokesperson to give a brief talk to a spokesperson to give a brief talk to the patient interest group.the patient interest group.

• The patient group must then vote to The patient group must then vote to decide who gives the most convincing decide who gives the most convincing argument, and state what convinced argument, and state what convinced them to vote that way.them to vote that way.

How did it turn out?How did it turn out?

• The Drug reps will have pushed the relative risk The Drug reps will have pushed the relative risk rather than absolute risk, and side effect profilerather than absolute risk, and side effect profile

• The PCT will have highlighted the cost to The PCT will have highlighted the cost to prevent each additional MI (NNT) and prevent each additional MI (NNT) and suggested patients should not receive Plavixsuggested patients should not receive Plavix

• The GPs will have been caught in the middle!The GPs will have been caught in the middle!

• The patients will have found it difficult to see The patients will have found it difficult to see beyond their own interestsbeyond their own interests

Notes from the full paperNotes from the full paper

• In most cases, there was no significant In most cases, there was no significant difference in all cause mortality between difference in all cause mortality between the two treatment arms (not mentioned in the two treatment arms (not mentioned in abstract)abstract)

• The side effect profile is similar with no The side effect profile is similar with no differencesdifferences

• The study was funded by the makers of The study was funded by the makers of Plavix, and no conflict of interest was Plavix, and no conflict of interest was statedstated

Critical appraisal summaryCritical appraisal summary

• Consider the motives behind presentation Consider the motives behind presentation of results by the authorsof results by the authors

• Ask yourself if the study ‘fits’ your patientsAsk yourself if the study ‘fits’ your patients

• Ask yourself if there is a conflict of interestAsk yourself if there is a conflict of interest

• Dont be frightened by high power Dont be frightened by high power statistics – you should be able to ask the statistics – you should be able to ask the same question of any trial – how many same question of any trial – how many patients do I have to treat, and what is the patients do I have to treat, and what is the cost to prevent one event. cost to prevent one event.