Lecture 34: Evidence-based practice

Question 1

Evidence-based practice combines what three aspects?

Answer 1

• the best available research evidence
• clinical expertise
• patient values and choices

Question 2

One of the aspects of evidence-based research is having the best available research evidence. What does this mean?

Answer 2

When deciding (for example) what treatment to give people, the evidence should already be pre appraised for clinicians or if it is new, the doctor might look at original documents.

Question 3

What is pre appraised evidence that clinicians should use when deciding what treatment to give patients?

Answer 3

Systematic reviews (or pre-appraised research) provide clinicians with a synthesis of high-quality, empirical research (based off observation not off theory) that addresses treatments of a medical/health condition.

Question 4

One of the aspects of evidence-based research is having clinical expertise. What does this mean?

Answer 4

The doctor has to use their experience to decide what treatment to give a patient

Question 5

One of the aspects of evidence-based research is having patient values and choices. What does this mean?

Answer 5

You have to take into account what the patient wants and their priorities

Question 6

One of the examples to show why it is important to use the best available research evidence is James Lind giving 12 patients different potential cures for scurvy. It was found that citrus provided the best cure which was different from two different authorities were recommending. What three things can we learn from this?

Answer 6

1. the expert opinion may be wrong
2. a trial is the best way to identify effective treatments
3. dissemination of evidence is important

Question 7

Define dissemination

Answer 7

the action or fact of spreading something, especially information, widely

Question 8

Another example to show why evidence based practice was when hormone replacement therapy (oestrogen and progestogen) was used to treat coronary heart disease. Intermediate outcome trials were conducted to show a decreased total cholesterol, LDL and TAGs and an increase HDL, there were trials on non-human primates and observational studies. All of these suggested that HRT could be used to treat coronary heart disease until an RCT done in 2002 shows that there was increased risk of heart disease. Despite being a few positives, the harms outweighed the benefits. What can we learn from this?

Answer 8

1. it is dangerous to rely o animal studies, observational studies, and trials of intermediate outcomes to determine the benefits of a treatment
2. it appeared that HRT reduced risk of coronary heart disease, but combined evidence from randomised controlled trials shows no overall benefits
3. is caused avoidable things such as breast cancers, strokes, pulmonary emboli
4. evidence is constantly evolving

Question 9

A third example to show why evidence based practice was when animal studies suggested that nimodipine might reduce death and disability following ischaemic stroke but so a study was conducted on humans and showed only a benefit in men which is very unusual. Cochrane conducted RCTs conducted with a placebo concluded that there was no evidence of benefit.
This prompted researchers to do a systematic review of the animal studies which found that the animal studies showed no evidence of benefit so it should not have been used in the first place. It also showed that the animal and human trials were going on at the same time which you are not allowed to do. What can we learn from this?`

Answer 9

1. there was poor animal studies done
2. there was enthusiasm for theoretical benefit of nimodipine which lead to trials in humans
3. no benefit was found

Question 10

The fourth example was when in conferences, it was suggested that there is a link between MMR vaccine and autism, despite the paper saying that there was proved to be no association. What can we learn from this?

Answer 10

1. it is impossible to draw any conclusions about a supposed relationship between MMR vaccine and autism from a case series
2. there was a drop in immunisation rates and increase in measles cases

Question 11

Good evidence is vital, otherwise there is a danger that: (4)

Answer 11

1. ineffective treatments are used
2. give treatments for which the harms outweigh the benefits
3. fail to provide existing effective treatments
4. provide expensive new treatments which may not be any better than the existing, less expensive alternatives

Question 12

What can we simply not rely on?

4

Answer 12

• theories about effectiveness of treatments
• professional opinion
• animal studies
• trials with intermediate end points

Question 13

What do we require evidence from

Answer 13

well designed, well conducted, and well reported randomised controlled trials which measure clinically meaningful outcomes