Using information from research on populations to help with clinical decisions

Question 1

What is epidemiology?

Answer 1

the study of patterns of health and illness and associated factors at the population level. It helps in the identification of risk factors for disease and determining optimal treatment approaches

Question 2

What are some types of clinical questions?

Answer 2

effectiveness
diagnosis
frequency
prognosis
what is the patient experiencing
aeitology/risk factor

Question 3

Which study designs are best for:

1. frequency and rate
2. aetiology and risk factors
3. prognosis
4. diagnosis
5. effectiveness
6. experiences

Answer 3

1. cross sectional, cohort
2 . ecological, cohort, case-control 
3. cohort
4. (special) cross sectional
5. RCT
6. qualitative research

Question 4

What are the 3 components of evidence based medicine?

Answer 4

individual clinical expertise
best external evidence
patient values and expectations

Question 5

ASSESS

Answer 5

• What is the best study design to answer your clinical question
• Consider individual components of your question
  PICO:
  Population, Intervention, Comparator, Outcomes

Question 6

At it simple appraisal asks:

Answer 6

Does the study address a research question which is relevant to my clinical problem - is there a match between my PICO and the study question
Did they use the study design most likely to provide a valid answer?
Was the study done well?
What were the results?

Question 7

How to appraise the quality of an RCT

Answer 7

• randomisation
• concealed allocation
• intervention and comparator groups were similar
• follow-up was complete and sufficiently long
• intention to treat analysis
• outcomes were measured blind

Question 8

What is selection bias?
What is attrition bias?
What is allocation bias?

Answer 8

Selection bias = insufficient randomisatoin
Allocation bias = allocation not concealed
Attrition bias = loss to follow-up, those that are high risk may not complete the trial

Question 9

What is intention to treat analysis?

Answer 9

Patients are analysed according to the original group they were randomised to

Question 10

How is risk difference calculated?

Answer 10

(number of affected / total in that group )

- (number affected / total in that group)

Question 11

How is relative risk calculated?

Answer 11

risk in first group / risk in second group

Question 12

How is number needed to treat calculated?

Answer 12

1/risk difference

Question 13

How do you interpret the following?

1. Relative risk of 1
2. Relative risk of more than 1
3. Relative risk of less than 1

Answer 13

1. no difference between treatment and comparator
2. more outcomes in treatment group compared to comparator group
3. less outcomes in treatment group

Question 14

How do you interpret the following?

1. Risk difference of 0
2. Positive risk difference
3. Negative risk difference

Answer 14

1. no difference between treatment and comparator
2. more outcomes in treatment group
3. more outcomes in comparator group

Question 15

What is the general interpretation of NNT?

E.g. what is the interpretain of NNT = 4.5

Answer 15

Number of patients you would need to treat to obtain 1 additional beneficial outcome compared to the comparator
Would need to treat an extra 5 patients with chiropractic treatment rather than physiotherapy to achieve one more patient with no pain at 3 months

Question 16

Explain the pincicples of chance and precision

Answer 16

Chance p less than 0.05, the probability of observing this result due to chance is less than 0.05%
95% confidence intervals, 95% of the time the true result will be within 95% CI limits

Question 17

What is meant by the ACT in AAAA?

What questions need to be asked?

Answer 17

What are the implications for of the results of my patients?
Were all important outcomes considered?
Are the patients in the trial similar to mine?
What is the cost of the intervention?
What other treatments are available? What is their cost?

Question 18

What are the advantages of systemic reviews?

Answer 18

• unusual if there isn’t more than one study addressing a particular problem
• efficient if reviews summarise all available studies
• apply scientific principles, including appraisal of included studies with the aim of providing reliable and unbiased results
• can provide greater precision of results as a result of statistically providing information about the generalisability and consistency of effect
• can be used to identify missing information.. the need for primary research