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The initial studies on the occurrence of dental fluorosis carried out by McKay in the early 1900s are examples of what epidemiological method or approach?
- Uncontrolled observation (descriptive)
- Observation or clinical impressions in a natural population (no control groups)
- Can NEVER prove a cause and effect relationship
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What are the methods of study design for epidemiologic studies?
- Uncontrolled observation (descriptive, formulation of hypothesis)
- Focuses on person, place and time, develops a hypothesis
- Controlled observations (analytical)
- Experimental observations (clinical trials)
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What are the essential elements of the philosophy of preventive dentistry?
- Biologically and technically excellent dental services
- Sound preventive methods or techniques
- Effective communication to patients
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A cross-sectional survey is the best approach to determining what measurement of a disease?
Best for estimating prevalence of a disease
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What is an example of primary prevention?
- Pre-pathologic: free of disease
- Ideal level: health education, topical F- application, periodic dental examination
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What is an example of secondary prevention?
- Disease already present, but in early stages
- Get the disease under control
- Arrest it and help the patient return to primary level through dental prophylaxis, scaling/root planning, restoring a vital tooth with a metallic or composite restoration
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What is an example of tertiary prevention?
- Disease at an advanced stage
- Prevent further deterioration
- Rehabilitate patient to a functional level by providing fixed or removable prostheses, extracting a tooth that is a source of infection, treating a tooth endodontically with root canal treatment
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A longitudinal study is the best approach to determine what measurement of a disease?
- Prospective: best approach for obtaining accurate data
- Minimizes the chance of bias because everyone is healthy when the study starts
- Use a control group
- Best approach for estimating the incidence of a disease
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Describe a risk factor.
- A factor that increases the chances or likelihood that an event will occur
- This factor can be modified to change the level of risk (ex/ stop smoking)
- If the risk factor is removed, the risk of disease diminishes
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Describes a risk marker.
An attribute associated with the increased probability of a disease, but not the cause of it (ex/bleeding on probing and periodontal disease)
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What is the best study design to determine the cause of a disease?
Experiemental observation (clinical trial): prospective/longitudinal
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What property of an ideal index is concerned with the reproducibility of an index?
Reliability, calibration of experienced examiner
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What property of an ideal index is concerned with being amenable to statistical analysis?
- Quantifiability (can be expressed statistically as mean, median mode)
- Must be able to assign a number on a scale for the disease with specific criteria for each number on the scale.
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In defining the methodology of epidemiology operationally, what skills are considered the absolute prerequisite or sine qua non?
Clinical skills, laboratory skills, field observation
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What are examples of RISK factors in the etiology of dental caries?
Poor dental hygiene, irregular visits to dentist, low saliva flow
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If dental caries is an infectious disease that results in cavities or cavitation of the tooth, does surgical repair of the cavity cure the disease?
No, just cures the symptoms, but recurrent disease is possible because dental caries is a chronic disease and it has an advantage over the host.
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How do you determine the prevalence, incidence and fatality of a disease from data presented in a table?
- Prevalence: number of total cases at one specific point in time/total population *100
- Incidence: number of new cases over a period of time/average number of people at risk for the disease * 100
- Fatality: number of deaths over total number of diagnoses
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What is the name of the survey that examines data, interviews and specimens from individuals in the United States?
NHANES: National Health and Nutritional Examination Survey
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What criteria must be met absolutely, to accept a given exposure as a risk factor for a particular disease?
- Needs three criteria to be considered a risk factor:
- 1. Statistical association (frequency must vary by exposure)
- 2. Time sequence (exposure must precede disease)
- 3. Absence of error (must not be the result of error)
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What is the epidemiological approach used by Dean in the “21 Cities Survey”?
Controlled observations
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Epidemic:
occurrence of illness or outbreak in a community clearly in excess of normal expectancy and derives from a common or propagated source
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Endemic:
Usually prevalence of a given disease within a given geographic area
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Dynamics:
- pattern of distribution over time
- Concerned with trends, calendar time, physiologic cycles, age, seasonality, or interval between the exposure and onset of disease
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Epidemiology:
- The study of the distribution pattern and dynamics of any observable characteristic of humans in a population
- o Simplest definition: study of the determinants of disease
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Three tools of Epidemiology:
- Clinical skills
- Laboratory skills
- Field observations (absolute prerequisite or sine qua non (essential condition or element)
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Levels of scientific Evidence:
- Systematic Review: done by experts and is unbiased, rules-based and could be repeated
- Randomized Controlled Trials
- Cohort Studies
- Case Reports
- Narrative Reviews, Expert Opinions, Editorials
- Animal and Lab Studies
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Objectives of Epidemiology:
- Increase our understanding of the natural history of a disease thereby leading to methods of control and prevention
- To identify the determinants and risk factors that lead to disease
- Identify the person, place and time factors relative to disease
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Methods of Epidemiology Uncontrolled Observatoin (Descriptive)
- • Formulation of Hypothesis
- • No control groups
- • Can NEVER prove a cause and effect relationship
- • McKay Study (Colorado Brown Stain on teeth observed)
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Methods of Epidemiology: Controlled Observations (Analytical)
- • Focuses on person, place and time
- • Dean Study (Analyzed fluoridation levels in particular 21 cities study)
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Methods of Epidemiology: Experimental Observations (Clinical Trial)
- • Community demonstration of Fluoridation in water (Grand Rapids, MI)
- • Risk Factor: attribute that increases the probability that an event will occur and this attribute can be modified
- o Three Criteria to be considered a Risk Factor:
- Statistical Association: frequency MUST vary by exposure
- Time Sequence: Exposure MUST precede disease
- Absence of Error: MUST not be the result of error
- o If the risk factor is removed, the risk of the disease diminishes
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Causality:
- a certain factor results in a particular outcome
- o Criteria must be met:
- Consistency of Association
- Strength of association
- Degree of exposure (dose-response)
- Time sequence of events
- Biologic Plausibility
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Host-Agent-Environment Triad
- o Health: host is clearly in control and the environment doesn’t give a significant advantage to either the host or the agent
- Can have health because the environment favors the host (Ex/ F in water)
- o Disease: the agent is clearly in control, and the environment doesn’t give a significant advantage to either the host or the agent
- o Chronic Disease: the agent has a slight advantage over the host
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Methods of Study Design: Prospective (Longitudinal)
- Advantages:
- • Best approach for obtaining accurate data
- • Best approach for estimating the INCIDENCE of a disease
- Disadvantages:
- • Most expensive
- • Lose subjects over time
- • Impossible to study a rare disease
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Methods of Study Design: Retrospective (Case-Control)
- Advantages:
- • Subjects don’t drop out
- • Best approach for studying rare diseases
- • Most inexpensive
- Disadvantages:
- • Information about past events may be absent
- • Choice of controls is crucial
- • Sample from the population may not be representative of the real world
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Methods of Study Design: Cross-Sectional (Survey)
- Advantages
- • Simplest of all approaches
- • Best method for estimating the PREVALENCE
- • Useful info in the shortest period of time
- Disadvantages:
- • Sample may not be representative of population
- • Sample may be biased
- • Measuring Health and Disease in populations
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Morbidity:
refers to the occurrence of illness
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Mortality:
refers to the occurrence of death
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Fatality:
- refers to the number of deaths occurring divided by the number of people diagnosed with disease
- Ex/ Tooth fatality=number of missing teeth/Dental Caries Experience (DMFT)
- Mortality/Morbidity
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Prevalence:
measures the proportion of persons affected by a disease at ONE SPECIFIC point in time
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Incidence:
measures the rate of occurrence of new disease between TWO POINTS IN TIME (New cases only)
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Epidemiological Index:
- Numerical valuce that describes the relative status of a population on a graduated scale with definite upper and lower limits
- Attempts to quantify a clinical condition
- Unlike the absolute or definitive diagnosis, an index will only estiame the relative prevalence of a clinical condition
- Criteria of an Ideal Index:
- • Validity
- • Reliability
- • Clear Objective definitions and Simple to Use
- • Amenable to statistical analysis: must have numerical data on a graduated scale
- • Sensitivity
- • Acceptability
- • Levels of Prevention and Control of Diseases
- o Primary: Pre-pathologic, free of disease, IDEAL LEVEL
- Health Education, Topical Fluoride application, periodic dental examination
- o Secondary: disease already present, but in early stages, get the disease under control!
- Dental prophylaxis, scaling/root planning, restoring a vital tooth with a metallic or composite restoration
- o Tertiary: Disease in advanced stage, prevent further deterioration, rehabilitate patient to a functional level
- Fixed or removable prostheses, extractions, endodontics
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Three Essential elements of preventive philosophy
- Biologically and technically excellent dental services
- Sound preventive methods or techniques
- Effective communication
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Instruction Model:
- Assess (pre-test)Instruction (demonstrate on model and use graphics)
- OR Clincal instruction (demonstrate in patient’s mouth using HAND MIRROR)
- Patient Demonstrates Skill (make adjustments and offer encouragement)
- Re-Assess
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What is EBD?
- • EBD will provide you with the recommendations based on the best available evidence
- • Process that is based on going from the evidence to the synthesis of the evidence to narrowing down to the best available evidence to finally applying the polices developed from the EBD
- • EBD is a PROCESS: start with a patient with clear, defined complaints, and ends with a patient and a solution to the problem
- o PICO question: defines the population, the intervention and the clinical outcome
- o Must go through a process to identify what is best from the available evidence= Evidence-Based Research
- EBD is an umbrella that includes EBR
- Systematic Review: translating information into revised clinical guidelines
- • Results in a consensus statement (like a conclusion, a consensus about all of the available evidence)
- o Evidence-based Practice is a result of this process
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Who does EBD?
- • EBD is a cooperative endeavor
- • If you are doing EBD, you will need to interact with a group of people (researchers, clinicians etc)
- • This field is only 40 years old: The Cochrane Collaboration started the idea
- • Systematic Reviews verified by the Cochrane group
- • IADR: International Association for Dental Research
- • Center for EBD
- • IF-EBD-CER
- • Journal of Evidence-Based Dental Practice, Journal of Evidence-Based Dentistry
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How do we do EBD?
- • There is no way to actually read and absorb all of the information that is published every year
- • Somehow, you need to synthesize all of the info without reading everything yourself
- • Outcome of EBR: Systematic Review because it is a systematic process of synthesizing the evidence
- 1. EBD is driven by the patient clinical needs
- 2. EBD utilizes the best available evidence
- 3. In EBD, the best available evidence arises from research
- • This generates the consensus statement, which is written in a way that is useful to the clinician
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THE PICO QUESTION:
P=Population, I=Intervention, P=Prediction/C=Comparison, O=Outcome
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Accessing the Sample for an EBR project:
- Search the available research literature
- o MEDLINE/PUBMEDRefine the search using MeSH words
- o Consider limitations of sampling procedure
- o Publication Bias: language
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Level of Evidence Analysis
- o Evaluate a body of evidence based on “what” was done
- o Acceptable Sampling AnaylsisEvaulate a body of evidence based on “how” the research was done and quantify the “quality of the evidence” based on established criteria of research methodology, design and statistical analysis
- o How do you establish the criteria for good or bad research?
- Acceptable sampling
- Meta-analysis: analysis that goes across many papers
- Fixed- model meta-analysis
- • Systemic Review<->Meta Analysis
- o Both lead to Research synthesis, which includes search, inclusion/exclusion, level of evidence, quality of evidence, inference, consensus
- BEST AVAILABLE EVIDENCE=Research synthesis
- We want to use the systemic reviews that utilize meta-analysis
- o Individual Patient data analysis: within the context of EBD, there are individual people that are within groups that qualify as target population for clinical trials and the evidence works well for them.
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When is a meta-analysis appropriate?
- On a given PICO question, there can be multiple systematic reviews
- But, you must do the research synthesis to find the best available information
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ADA Center!!
- They simplify everything for the clinician
- o They have evidence reviews that reduce the best available information to 800-1000 words
- • We are integrating systematic review into our clinical advice
- • Set PICO question
- • Search and inclusion/exclusion criteria
- • Level of evidence and quality of evidence
- • Acceptable sampling
- • Meta-analysis
- • R-AMSTAR
- • Consensus statement
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