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Economic Models and Infection Prevention

SHEA Spring 2012 Nicholas Graves Advanced Epidemiology Methods
by

Nicholas Graves

on 4 November 2014

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Transcript of Economic Models and Infection Prevention

what can economic models tell us

the information required

using the information

using information on effectiveness
Scarcity forces choices

Spend the money in the best way
More costs
Less costs
Less QALYs
More QALYs
Always start here
This is $50,000 per QALY
How much will costs increase
How much cost will be saved
How much health benefit (QALY)


the irrelevance of 0.05

study quality
this is $3M
50% chance it’s a bad decision (10/20)

50% chance it’s a good decision (10/20)

10% chance it’s harmful to health (2/20)

20% chance it’s cost saving (4/20)
what can economic models tell us

the information required

using the information

using information on effectiveness


the irrelevance of 0.05

study quality
what can economic models tell us

the information required

using the information

using information on effectiveness


the irrelevance of 0.05

study quality
what can economic models tell us

the information required

using the information

using information on effectiveness


the irrelevance of 0.05

study quality
30% chance it’s a bad decision (6/20)

70% chance it’s a good decision (14/20)
Reducing uncertainty is valuable
49 papers + 1 thesis
evidence discounted for two reasons

1. failed arbitrary test of significance at 0.05
2. poor quality designs
what can economic models tell us

the information required

using the information

using information on effectiveness


the irrelevance of 0.05

study quality
Imagine the same trial with four different sample sizes
four versions of the same parameter with reducing variances
what can economic models tell us

the information required

using the information

using information on effectiveness


the irrelevance of 0.05

study quality
evidence discounted for two reasons

1. failed arbitrary test of significance at 0.05
2. poor quality designs
Rigour ~ INTERNAL BIASES




Relevance ~ EXTERNAL VALIDITY
sample size
randomisation
controlling for differences
too short a follow up period
variation in the intervention
poorly defined or described study populations.
Improving the quality of studies
bar set low - misleading estimates
study 1
study 10
study 8
study 7
study 6
study 5
study 4
study 3
study 2
study 9
High Quality
study 1
study 10
study 8
study 7
study 6
study 5
study 4
study 3
study 2
study 9
Low Quality
study 1
study 10
study 8
study 7
study 6
study 5
study 4
study 3
study 2
study 9
How the actual study deviates from the idealised version of it will reveal all internal and external biases, which are dealt with separately
The next steps are to find an appropriate statistical model for including both internal and external bias adjustment, and then to quantify bias.
Tools for identifying internal biases and external biases separately and by different members of the research team with different skills are provided by Turner et al.
The end result of these steps is an bias adjusted meta-analysis that emerges from methods that can be implemented routinely
Distributions are required for each bias in each study, which could be gained from eliciting expert opinion by extracting qualitative details of study characteristics that might be a source of bias for each bias category and then revealing ranges of the bias on elicitation scales
Indeed the authors suggest that for each study the bias elicitation process lasted one hour plus a minimum of one hours preparation and then the completion of the bias check list required at least three hours.
identify all potential internal and external biases by imagining an idealised version of each study under consideration and writing a mini-protocol for it
neither one or the other
bar set high - large uncertainty
study 1
study 10
study 8
study 7
study 6
study 5
study 4
study 3
study 2
study 9
The ideal situation
Which data to use?
“this review has not been been able to provide evidence of the effect of interventions to promote hand hygiene”
“the findings should not be taken to suggest that attempts to increase compliance or reduce HCAI are not worth undertaking”
“logically hand hygiene seems an important and cost-effective intervention.......and should continue to be promoted in all clinical settings”
Judgements
Decisions
Any Questions?
Full transcript