Practice-Based Evidence

Systematic Review

Randomized Double-

blind Control Studies

Case Controlled

Studies

Nelson Fok Provincial Manager

Scientific Advisory Team

nelson.fok@albertahealthservices.ca

Nelson Fok Provincial Manager

Scientific Advisory Team

nelson.fok@albertahealthservices.ca

Incorporating Practice-Based Evidence into

Decision Making απόδειξη

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evidência

докази

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Beweis

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Incorporating Practice-Based Evidence into

Evidence-Based Practice

What is „evidence‟?

Oxford Dictionaries-

The available body of facts or information indicating whether a belief or proposition is true or valid

David Sackett, the founding father of Evidence

Based Practice (EBP), defined EBP in 1996 as

“Evidence based medicine is the conscientious,

explicit, and judicious use of current best evidence

in making decisions about the care of individual

patients”

“The practice of evidence based medicine

means integrating individual clinical

expertise with the best available external

clinical evidence from systematic

research.”

What constitute evidence?

What constitute evidence?

What constitute evidence?

Evidence of Efficacy of an Intervention

Level of Evidence

Type of Evidence

1++ High quality meta-analyses, systematic reviews of RCTs or RCTs with a very low risk of bias

1+ Well conducted meta-analyses, systematic reviews of RCTs or RCTs with a low risk of bias

1- Meta-analyses, systematic reviews of RCTs or RCTs with a high risk of bias

2++ High quality systematic reviews of, or individual high quality non-randomised intervention studies (controlled non-randomised trial, controlled before-and-after, interrupted time series0 comparative cohort and correlation studies with a very low risk of confounding, bias or chance

2+ Well conducted, non-randomised intervention. Comparative cohort and correlation studies with a high risk of confounding, bias or chance

2- Non-randomised intervention studies, comparative cohort and correlation studies with a high risk of confounding, bias or chance

3 Non-analytical studies (case reports, case series)

4 Expert opinion, formal consensus

EBP is the art of integrating the best evidence from

epidemiological research with clinical expertise by:

1. Assess your

patient

2. Ask the right question

3. Access the evidence

4. Appraise the evidence

5. Apply the evidence 6. Audit clinical

practice

7-Steps of Evidence-Based Methodology

1. Systematically identify the evidence

2. Systematically selecting the best available evidence from that identified

3. Systematically evaluating the evidence (critical appraisal)

4. Objectively reporting the relevant findings and quality of the evidence

7-Steps of Evidence-Based Methodology

5. Synthesizing multiple evidence reports

6. Deriving overall conclusions and recommendations from the evidence synthesis

7. Changing the conclusions when more evidence alters the best available evidence

EBP: use of current best evidence in making decision

Process used and expected by clinicians

What constitute evidence?

• Not many RCT being conducted to evaluate the effectiveness of intervention in EPH – very few „systematic reviews‟

• Except for infectious diseases, „evidence‟ mostly through the reporting of practices (case reporting) or expert opinion

What constitute evidence?

Case-reporting and expert opinion considered not the most reliable form of evidence from clinical standpoint

Public Health Evidence

Case-reporting and expert opinion considered not the most reliable form of evidence from clinical standpoint, but in public health, intervention can be verified and confirmed through observation, something epidemiology cannot provide

-Microwave -Running water -Refrigerator NOT at ambient temperature !!!

Public Health Evidence

Only two published studies (case reporting) which measured temperature on the surface of thawing birds and microbial growth

Public Health Evidence

Klose et al. Food Technology 1968 Reported on the growth of spoilage bacteria in thawing turkeys that ranged in weight from 4 to 22 pounds at temperatures of 12.8, 21.1, and 28.9oC. The authors concluded that ambient (room) air temperature thawing, at 20oC and below, is a satisfactory thawing procedure.

Public Health Evidence

It took about 15 hours for the middle of a 22-pound turkey to get to 0oC, while the surface temperature rises to 12oC or less. In this amount of time, there would be about 4 multiplications of spoilage bacteria and non-detectable multiplications of Salmonellae

Public Health Evidence

Jimenez etal, Dairy Food and En. Sanitation 2000

•Six chicken carcasses 3 kg each inoculated with Salmonella Hadar and then frozen

•Thawed at room temp, under water and refrigerator

•Temperature measured at 3.5 cm inside the breast and the other under the skin of the thigh

Public Health Evidence

•Thawing at room temp of 22oC for 14 hours. Time required for temp 3.5 cm inside the breast to reach 4.4oC was 13.75 hours

•Temp just under skin never reached >5oC

•All three methods resulted in 1 log/g reduction

•Concern with Listeria if thawing in refrigerator

•Small sample size

Public Health Evidence Common sense rules of evidence:

•Evidence from human studies?

•Is the association strong?

•Is the association consistent from study to study?

•Is the temporal relationship correct?

•Is there a dose-response gradient?

•Does the association make epidemiologic sense?

•Does the association make biologic sense?

•Is the association specific? Sackett DL, Clinical Epidemiology

Public Health Evidence •Evidence from human studies? Random group, apply to general public

•Is the association strong?

Odds ratio, relative odds

•Is the association consistent from study to study?

Repetitive demonstration by different investigators

Public Health Evidence •Is the temporal relationship correct? Consistent sequence of events of exposure to the cause, followed by the occurrence of the outcome

•Is there a dose-response gradient?

And perhaps reverse gradients?

•Does the association make epidemiologic sense?

Agreement with our current understanding of distributions of causes and outcomes in man

Public Health Evidence •Does the association make biologic sense?

Agreement with current understanding of the responses of cells, tissues organs?

•Is the association specific?

Limit association to a single putative cause and single effect

Public Health Evidence • Cryptosporidium and fecal

accident in swimming pools

• Ct value of 9,600 mg-min/L

Public Health Evidence CT value of 9,600 mg-min/L to control Cryptosporidium (fecal accident) in swimming pool was based on water treatment technology

•Originated during Cryptosporidium outbreak in Milwaukee

•Public health department reported that the use of chlorine for a long enough period of time was sufficient to control Cryptosporidium in swimming pool

Public Health Evidence •Never verified for pools or analyzed by statistic

•The exact log removal efficiency was NEVER determined (in theory need 5-log removal)

•This practise-based evidence adopted by agencies throughout the world and no outbreak have ever occurred after this CT value was used

•Result never analyzed by statistic but verified by observations

Public Health Evidence • Ct value was changed in 2008 to 15,300 mg-min/L based on one paper (case report) by Shields (J Water and Health 2008)

•Recreational water condition (pH 7)

•Accepted by CDC

Public Health Evidence

• Acceptable to use practices-based

evidence to formulate evidence-based practise in environmental public health

• But MUST have good evidence that is based on science, understand what it means and how to translate the knowledge into practise

Questions

or issues

being

addressed –

real or

perceived

Application

of science

evidence

based on

situation

MAC lowered from 50 µg/L to 10 µg/L in 2006

No Drinking Water Advisory :

Due to concentrations of arsenic in the X water system that exceed the MAC, AHS is advising all residents and businesses in the Village to stop drinking the tap water immediately. Additionally, tap water from this system should not be used to make baby formula, baby food or juice at this time; nor for the preparation of any food or beverage

Public Health Evidence

No Drinking Water Advisory:

To ensure safe drinking water is immediately available, Village X will deliver bottled water directly to all affected residents this evening. Beginning tomorrow, the bottled water will instead be made available to all residents for pick-up at xxx

Using Evidence

No Drinking Water Advisory:

“While the concentration of arsenic at current levels presents a very low risk to public health, we feel it is prudent to ensure residents and users of this water are aware of the potential long term health risks, and advised of appropriate steps to reduce their intake of arsenic,” says Dr. XX, Medical Officer of Health, AHS

Using Evidence

Knowing the facts is important because it can influence your message: evidence-based decision making

Arsenic at 25 µg/L (MAC 10 µg/L)

Five year compliance period after the released of new MAC by Health Canada

Using Evidence

MAC is lifetime exposure

Subchronic exposure level (5-years) for young children (aged 0 to 6 years) is 0.005 mg/kg-day or 5 µg/kg-day

A 0-6 month old infant with 100% intake from formula milk made with As level of 30 µg/L; with average volume (for 6 months old) of 0.7L and average body weight of 7.8 kg

Total As intake = (30 µg/L x 0.7 L)/7.8 kg = 2.6 µg/kg/day

Public Health Evidence

MAC is lifetime exposure

Subchronic exposure level (5-years) of 0.005 mg/kg-day or 5 µg/kg-day

For two year old child, average daily water consumption is 0.7 L, average As intake in food is 14.9 µg and average body weight of 12.8 kg

Total As intake = [(30 µg/L x 0.7 L) + 14.9 µg]/12.8 kg = 2.8 µg/kg/d

Public Health Evidence

MAC is lifetime exposure

Subchronic exposure level (5-years) of 0.005 mg/kg-day or 5 µg/kg-day

For adult with average daily water consumption of 1.5L, average As intake in food of 42 µg and average body weight of 70 kg

Total As intake = [(30 µg/L x 1.5 L) + 42 µg]/70 kg = 1.24 µg/kg/d

Public Health Evidence

Instead of a no water advisory (crisis), issued a statement in the villages‟ newsletter that they send out monthly to each resident outlining actions taken

Turning a crisis situation with immediate no water advisory causing panic and questions to a nicely controlled communication PR event using good science and common sense

Public Health Evidence

EBP is the art of integrating the best evidence from

epidemiological research with clinical expertise by:

1. Assess your

patient

2. Ask the right question

3. Access the evidence

4. Appraise the evidence

5. Apply the evidence 6. Audit clinical

practice

FLUORIDE Fluoridation of

Drinking Water

Public Health Evidence

One of the ten great public health achievement in the US from 1900 to 1999 (CDC) -Fluoridation reduces direct health-care expenditures through primary prevention of dental caries and avoidance of restorative care. -Per capita cost savings from 1 year of fluoridation may range up to $53 in larger communities with a high incidence of disease (CDC, unpublished

data, 1999)

Fluoridation of Water

One of the ten great public health achievement in the US from 1900 to 1999 (CDC) - Other studies have found fluoridation resulted in 60% of children caries-free compared to 5% prior to fluoridation -Drinking water with fluoride can reduce incidence of dental caries in children by 30-60%

Fluoridation of Water

Fluoridation of Water

-Fluoridation is about industry ridding itself of crude hazardous waste products...for a profit…by-product of phosphate rock mining -Fluoride is more toxic than lead…damage brain/mind development of children…abnormal behaviour in animals -Sodium fluorosilicate is considered by USEPA as hazardous products

Fluoridation of Water

-Osteosarcoma (tumour of the bone) (Cancer Causes Control 2006)…equivocal evidence of carcinogenic activity of sodium fluoride in male rats (Int. J. Cancer 1991) -Neurotoxic (Ann. NY Acad Sci 1997) -Birth defects (J. Dental Res 1979) -Immune system (J Dent 1994) -reducing IQ in humans (Fluoride 2000)

Fluoridation of Water

Science meets Policy

• Ethical, legal, social, political, scientific

considerations

• Engage Public?

• Role of government agencies?

• Local – National – International?

- Carcinogenic at >100 mg/L (IARC inadequate evidence)

- Renal necrosis at 50 mg/L - Skeletal fluorosis (increase

fluoride deposits in bone, substitute fluoride for hydroxy ions. Mineral crystals increase in density, become more brittle and more susceptible to micro-fractures) at 8 mg/L

- At 4 mg/L, increase risk of hip fractures

Fluoridation of Water

- LOAEL (dental fluorosis) is at 2 mg/L

- Benchmark Dose at 1.87 mg/L for severe fluorosis

- NOAEL at 1 mg/L - RfD (oral) 0.06 mg/Kg/day for 20

kg child - Drinking water concentration of

0.7 mg/L, consumption of 1L water for a child provides 0.035 mg/kg/day

Fluoridation of Water

Science

Background Information

Policy

Government agencies around the world (World Health Organization, USEPA, US CDC, Health Canada, EU, UK, Australia, Japan) have all examined the issue. As policy makers, based on scientific facts presented to them, have all decided that fluoridation of drinking water is SAFE at concentration being used (lowered from 1 mg/L to 0.7 mg/L) Fluoridation of water is NOT a health issue

Fluoridation of Water

Science

Background Information

Policy

US- last 5 years, 39 of 79 local referendums rejected fluoridation

- Petition to stop fluoridation - Clinicians and dentists prepared data

and tables to councillors to counter „bad‟ evidence by those opposing fluoridation

- Ranking of concerns: - Toxicity: level of evidence 3 - Carcinogenicity: level of evidence 3 - Skeletal fluorosis: level of evidence 1+

City voted to stop fluoridation

Fluoridation of Water

- National bodies examined the science behind the number and found fluoridation to be safe.

- The focus on these bodies is to determine 1. the acceptable level of fluoride in

water (MAC or MCL) 2. The operational level of fluoride to

prevent dental caries

Fluoridation of Water

- Local municipalities examined the issue looking at social concerns and found fluoridation not acceptable

- The focus of these bodies is to address local concerns within their power: 1. Dental fluorosis; and 2. Indiscriminate compulsive mass

medication

Fluoridation of Water

Local municipalities are not likely to second guess decisions made by WHO, Health Canada, USEPA and USCDC. These agencies all declared fluoridation to be safe. Local governments will entertain discussions on the issue to appear to be fair Information presented to policy makers MUST be tailored to address their concerns and answer their questions

Fluoridation of Water

Science

Background Information

Policy

What is good „evidence‟?

The questions local governments trying to answer are: •Do we need to fluoridate our water anymore as we have all these other sources of fluoride? •Will fluoridation of water contribute to increase rates of dental fluorosis?

Need to tailor evidence to target policy makers

Fluoridation of Water

Fluoridation of Water Indiscriminate Compulsive Mass Medication Health Canada response: -When fluoride is offered for sale in a final dosage form, used in large concentration and with a drug delivery system (dental rinse, toothpaste) and is labeled for therapeutic use, the products are considered drugs under the Food and Drugs Act and are regulated

Indiscriminate Compulsive Mass Medication Health Canada response: -Where minerals are added or where food is fortified with a mineral (e.g. iron in cereals) the food does not become a drug. Fluoride used in drinking water is therefore, not considered a drug under the Food and Drugs Act. Fluoridation is therefore NOT mass medication

Fluoridation of Water

Indiscriminate Compulsive Mass Medication Health Canada response: -Health Canada endorses the fluoridation of drinking water to prevent tooth decay, the decision to do so falls under the responsibility of provincial and territorial governments

Fluoridation of Water

Indiscriminate Compulsive Mass Medication Translation: -Fluoride is added to water to PREVENT a disease (dental caries), but we are not calling it a drug because it is only a mineral added to water. We do not regulate it and it is up to local government to decide if they want to add this non-drug mineral in water to prevent a disease

Fluoridation of Water

EBP is the art of integrating the best evidence from

epidemiological research with clinical expertise by:

1. Assess your

patient

2. Ask the right question

3. Access the evidence

4. Appraise the evidence

5. Apply the evidence 6. Audit clinical

practice

How to synthesize good evidence for policy development?

Steps for Policy Development

• Identify the issue – clear statement and goal with a good understanding of the health concern (real and perceived)

• Compilation of an inventory of public policies that could address the targeted health problem – with a reminder that many policies may have been formulated WITHOUT „evidence‟ but passed on through tradition

Steps for Policy Development

• Search grey and scientific literature. Review literature (common sense approach to evidence to determine validity of information)

• Examine policies and compare with literature to determine if the policies make scientific sense

• Construction a logic model based on temporal relationship

Steps for Policy Development

• Synthesis of the data and develop policy or procedure

• Refine data through deliberation with stakeholders

• Evaluate process

Example of evidence or science-based policy: BWA

• Boil water advisory – 3 to 5 minutes rolling boil and not allowing the use of kettles with automatic shut-off

• Not science based but „tradition‟, copy-and-paste from one health department to another

Example of evidence or science-based policy: BWA

• All enteric pathogenic bacteria destroyed at 60oC; Hepatitis A and norovirus at 65oC and Cryptosporidium at 73oC for 1 minute

• Depending on heating unit, may take up one minute or more for water to be heated up from 75oC to 100oC

Example of evidence or science-based policy: BWA

Bubbles will begin to form around 80oC and not a good indicator of boiling. Rolling boil is recommended to make sure time-temperature relationship of >70oC for 2 minutes to inactivate all pathogens

Example of evidence or science-based policy: BWA

Taking into account of altitude and atmospheric pressure:

•Lake Louise in Alberta is the highest permanent settlement in Canada. At 1,536 m water boil at 95oC and rolling boil for 1 minutes is sufficient

Example of evidence or science-based policy: BWA

Taking into account of barometric pressure:

• Depending on barometric pressure, boiling temperature may vary by +/- 3oC

• Rolling boil for one minutes (with cover) is still sufficient anywhere in Canada

Example of evidence or science-based policy: BWA

Electric kettles with auto shut-off is acceptable as they will heat water >90oC

Coffee makers usually perk coffee at >70oC, and coffee being held for at least 5 minutes is also acceptable

Example of evidence or science-based policy: BWA

Review of science-based evidence that make biological sense and satisfy temporal relationship being formulated into practice to make sure recommendations made for boil water advisory is sound

Translates science and evidence into prevention strategies and policies

What are the evidence on inspection and food safety?

How to determine where to apply the resource?

Motivation for

improved food

safety at

restaurants

Disclosure and Public pressure

Education and

training

Inspection and

deficiency compliance

Deterrence through fines, suspensions and closure

SOPs and HACCP

Foodborne

Illness

Prevention

Management attitude

Practice-Based Evidence

Systematic review of

scientific information

Practical expertise

Address real and

perceived risk