Non-communicable Disease Cluster Flashcards
What is a disease cluster?
Aggregation of cases in space and/or time in amounts that are believed or perceived to be greater than would be expected by chance.
I.e. O > E in t, p, p
What is a cluster assessment or investigation?
Systematic scientific process to determine if there is an increased number of cases of a specific disease/condition and to determine if there is a biologically plausible causal agent(s) for the disease.
True or false: most reported clusters have no identifiable causes and don’t need extensive evaluation.
True
What is the Texas Sharpshooter fallacy in relation to cancer clusters?
Drawing conclusions about the cause of a cluster while ignoring random chance and other explanations.
People look for similarities, ignore differences, and do not account for randomness.
Why is communication a key part of a cancer cluster investigation?
- Community distressed / anxious / concerned
- High degree of outrage
- Media interest / influence
What is the most likely explanation for a NCD cluster?
Chance distribution of biological events with complex multifactorial causation.
How common is cancer?
1 in 2 people will have had cancer by age 85.
Why is the long latency period (exposure to development) of cancer challenging for cluster investigations?
Difficult to determine cause because exposure may have occurred many years ago.
Why should cluster investigations be carried out even though a common cause is rarely identified?
To reassure and allay fear and anxieties of the public.
What are the principles of a cluster investigation?
- Protect human health (primary objective)
- Transparency / diligence
- Clear documentation
- Based on best available evidence
- Uncertainty analysis
What is the epidemiological measure typically used in cluster investigations?
Standardised incidence ratio - ratio of observed to expected number of cases.
Or standardised mortality ratio.
What are the 4 types of cluster investigation (QLD Health)?
- Type 1 - Inquiry response
- Type 2 - Data assessment
- Type 3 - Analytical assessment
- Type 4 - Research study
What is the purpose of a type 1 (inquiry response) cluster investigation?
To assess whether the cases reported by the informant could potentially be a cluster.
Who is the main decision-maker in a type 1 cluster investigation?
PHP
What data is collected for a type 1 cluster investigation?
- Informant data of cases and exposures
- May include standard literature and texts and/or use of existing data
Who make up the team for a type 1 cluster investigation?
PHP +/- senior local officer(s) of:
* Epidemiology and/or
* Environmental Health and/or
* Media / comms +/-
* Other experts
How long does a type 1 cluster investigation usually take to complete?
Less than 1 week
(0.5 - 20 person days)
What is the purpose of a type 2 (data response) cluster investigation?
To assess, using existing data, whether there is an excess number of cases meeting the case definition and sufficient exposure to a biologically plausible causal agent for the type of disease reported.
Who is the main decision-maker in a type 2 cluster investigation?
Assessment team +/- expert advisory committee to be formed.
What data is collected for a type 2 cluster investigation?
- Existing data
- Consult literature
What are the collection and analysis steps for a type 2 cluster investigation?
- Use existing data and consult literature
- Validate cases
- Ascertain complete list of ases
- Quantify study population
- Determine expected case numbers from reference population
- Conduct environmental appraisal of setting +/- sampling
Who make up the team for a type 2 cluster investigation?
PHP +/- senior local officer(s) of:
* Epidemiology and/or
* Environmental Health and/or
* Media / comms +/-
* Representatives of other stakeholder groups +/-
* Other experts
How long does a type 2 cluster investigation usually take to complete?
Weeks to months
(10 - 50 person days)
What is the purpose of a type 3 (data response) cluster investigation?
To quantify the excess of disease and undertake a detailed exposure assessment of biologically plausible causal agents
Who is the main decision-maker in a type 3 cluster investigation?
Assessment team with Expert Advisory Committee on cluster assessment (to be formed).
What data is collected for a type 3 cluster investigation?
- New data collected and analysed
- Epidemiological and environmental
Who make up the team for a type 3 cluster investigation?
PHP +/- senior local officer(s) of:
* Epidemiology and/or
* Environmental Health and/or
* Media / comms +/-
* Representatives of other stakeholder groups +/-
* Senior statistical officer +/-
* Other experts
How long does a type 3 cluster investigation usually take to complete?
Months to year
(50 - 300 person days)
What is the purpose of a type 4 (research study) cluster investigation?
To investigate biologically plausible hypotheses generated by the Type 3 assessment.
Who is the main decision-maker in a type 4 cluster investigation?
Large and specialised team (commonly outsourced).
What data is collected for a type 4 cluster investigation?
- New data collected and analysed
- Epidemiological
- Environmental and/or
- Experimental
Who make up the team for a type 4 cluster investigation?
Large groups of specialised members.
How long does a type 4 cluster investigation usually take to complete?
Months to year
(>300 person days - very high human resource)
