Investigating non-communicable disease clusters
Date published:
22 Sep 2015
The Australasian Faculty of Public Health Medicine (AFPHM) Victorian Regional Committee hosted a regional meeting on Wednesday, 2 September at the Victorian Health Promotion Foundation (VicHealth) in Carlton, Melbourne.
AFPHM members Dr Brett Sutton and Dr Michael Coory presented at the meeting on the topic of non-communicable disease cluster investigation.
Dr Brett Sutton
Dr Brett Sutton is an Advanced Trainee currently working at the Office of the Chief Health Officer.
His presentation titled “Non-communicable disease cluster investigations: protocols, practice and prickly issues” addressed what cluster investigations are, why they are done and the importance of communication with stakeholders.
Dr Sutton touched on the many and varied stakeholders, roles and responsibilities in the Victorian context.
He also spoke of the need to get communication right, as statistics and epidemiological robustness alone are unlikely to achieve acceptance from an affected community. “Promoting ‘facts’ alone is a good recipe for failure,” he said.
Dr Sutton outlined the recommended steps in an investigation, highlighting a recent Department of Health and Human Services response to a non-communicable cluster related to historical asbestos production.
This example brought home the critical role which community engagement plays and the importance of understanding ‘outrage’ and its genesis.
Finally, he highlighted the shift in our understanding of critical actions, with the complex issue of engagement now central to successful and effective public health outcomes.
Dr Michael Coory
Dr Michael Coory is a Public Health Physician with qualifications in medical statistics and clinical epidemiology. He is also a Director at the Therapeutic Goods Administration.
His presentation titled “Assessment of chance should be removed from protocols for investigating cancer clusters” touched on a related but uniquely epidemiological issue; that of p-values and confidence intervals.
Dr Coory explained that clusters suffer from an extreme form of the ubiquitous statistical problem of silent multiple comparisons. Does one compare only within Australia, or regionally, or globally? This effectively means that one can ‘construct’ whatever p-value one desires.
Despite this inherent problem, assessment of chance, using p-values and confidence intervals, is still considered important in cluster investigations and continues to be included in published protocols and reports.
Dr Coory spoke about how there are good pragmatic reasons for applying the concept of chance in most areas of epidemiology, but not in cluster investigations. He made the case that p-values and confidence intervals from cluster investigations are impossible to interpret. They confuse, rather than assist, decision-making.
Therefore, the assessment of chance should be de-emphasised in cluster investigation protocols and clusters could or should be framed as case series.