Lessons from Public Health Research

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Lessons from Public Health Research Paul Brown – Deputy Director, SWPHO SOUTH WEST OBSERVATORY CONFERENCE - 11TH May 2011 :

Lessons from Public Health Research Paul Brown – Deputy Director, SWPHO SOUTH WEST OBSERVATORY CONFERENCE - 11 TH May 2011


Outline Criteria for Public Health Evidence Determinants of the health of a population Examples: Florence Nightingale John Snow Smoking Vaccination Safety Camera partnerships Conclusions / lessons

The Bradford Hill Criteria:

The Bradford Hill Criteria A group of minimal conditions necessary to provide adequate evidence of a causal relationship between an incidence and a consequence Strength of association ( odds ratio ) Consistency Specificity Temporal relationship (temporality) - not heuristic; factually necessary for cause to precede consequence Biological gradient ( dose-response relationship ) Plausibility ( biological plausibility ) Coherence Experiment (reversibility) Analogy (consideration of alternate explanations)

Determinants of the health of a population :

Determinants of the health of a population consider the effects of each of the seasons of the year and the differences between them study the warm and the cold winds, the effect of water on the health must not be forgotten. Lastly, consider the life of the inhabitants themselves; are they heavy drinkers and eaters and consequently unable to stand fatigue, or being fond of work and exercise, eat wisely but drink sparely? Whoever would study medicine must learn of the following subjects:

Examples of evidence based decision making?:

Examples of evidence based decision making?

Florence Nightingale:

Florence Nightingale Nightingale discovered that the majority of deaths in the Crimea were due to poor sanitation rather than casualties in battle. But thought raw numbers were unlikely to impress ministers. Once those numbers were translated into a picture ....the message could not be ignored. Her findings persuaded the government of the need for better hygiene in hospitals.

John Snow:

John Snow By plotting the locations of those who contracted cholera on a map, Dr. Snow was able to demonstrate the significance of the Broad Street water pump to the outbreak. The strength of his map and other statistical studies was enough to convince the council to disable the water pump in Broad Street.


Smoking Sixty years ago, smoking was generally regarded as innocuous; Now it is recognised as the main cause of lung cancer, the world’s most common fatal cancer. Pioneering MRC researchers (Doll and Hill, 1950’s) established a link between smoking and cancer through the study of a cohort of British doctors


Smoking Over several decades, they identified the full hazards of smoking and the benefits of stopping Subsequently influencing public policy and behaviour. This has prevented millions of unnecessary deaths and culminated in a Government ban on smoking in enclosed places that will save the country billions of pounds. BUT IT HAS TAKEN A LONG TME!!

Vaccination: MMR :

Vaccination: MMR The importance of peer review and quality assurance First do no harm!!

Safety Camera partnerships :

Safety Camera partnerships Systematically searching for the available evidence, Pilkington and Kinra (2005) found no randomised controlled trials, but 14 observational studies addressed the topic and fulfilled the inclusion criteria. Although inappropriate for a meta-analysis, these studies consistently provided evidence favouring speed cameras' effectiveness. Reductions ranged widely across the studies for all outcomes—collisions (5%-69%), injuries (12%-65%), and deaths (17%-71%), but all studies showed a positive impact Yet.........

Conclusions / lessons:

Conclusions / lessons Hierarchy of evidence shouldn’t exclude the use of common sense/observation High quality/accuracy is essential Evidence is important pre and/or post intervention Continued use of evidence is paramount for continued improvements in the health of the population. Presentation is key to getting people to understand the message, and political/public support key to action it. Sometimes compelling evidence is ignored and interventions restricted or delayed.... due to many factors including lack of political, commercial or public appetite