Health policy, clinical epidemiology and screening Flashcards
policy
a plan or course of action intended to influence and determine decisions, actions, and other matters
Health Policy
A policy that pertains to the health arena
Some definitions of health policy
Policy actors: individuals involved in policy formulation : this includes members of legislature, citizens, lobbyists, and representatives of advocacy groups
Stakeholders: Individuals, organizations, and members of government affected by policy decisions.
Legitimization: Process of making policies legitimate ( i.e . acceptable to norms of society)
Interest Group: Group working on behalf of or strongly supporting particular cause
Policy actors:
individuals involved in policy formulation : this includes members of legislature, citizens, lobbyists, and representatives of advocacy groups
stakeholders:
Individuals, organizations, and members of government affected by policy decisions.
Legitimization:
Process of making policies legitimate ( i.e . acceptable to norms of society)
Interest Group:
Group working on behalf of or strongly supporting particular cause
what factors influence policy?
Research and Science
Interest groups
Public opinion
Social and economic factors
Policy cycle
START: policy definition/formulation/reformation then, Agenda Settings, then, Policy Establishment then, Policy Implementation then, Assess Policy
Problem Definition, Formulation, and Reformulation
Define problems and alternative
- formal & informal policy
actors
Most crucial phase of policy cycle
Problems should have public health significance and realistic and practical solutions
- Poorly defined problems
unlikely to have
successfully
implemented policy
Agenda Setting
Set priorities
- Formal&informal policy actors
Decide at what time to deal with a public health problem or issue
Determine who will deal with problem
- involve stakeholders
Barriers: Lack of information on risk; lack of coordination
Policy Establishment
Formal adoption of policies, programs, and procedures designed to protect society from public health hazards.
- Formal policy markers
Legitimization
Need empirical evidence on the public health hazard to support policy
Policy implementation
Put the policy into practice
- Government agencies
Consider political and social context
Understand interest groups that may be for or against policy
Barrier: Lack of government support
Policy Assessment/ Evaluation
Assess or evaluate effectiveness
- Refers to the determination of whether policy has met defined objectives and related goals
- May be accomplished by applying methods of epidemiology
Barrier: Lack of sound scientific data
Environmental Objectives
Facilitate assessment
- Assessed using information from monitoring program.
- Monitoring program needs to be adequate in quality and quantity of data
Evidence - Based public health
Adoption of policies, laws, and programs that are supported by empirical data
One of the most reliable forms of evidence comes from randomized controlled trials
Cost- Effectiveness Analysis
A procedure that contrasts costs and health effects of an intervention to determine weather it is economically worthwhile
Decision Analysis
Involves developing a set of possible choices and starting likely outcomes linked with those choices, each of which may have associated risks and benefits
Ideally, policy-makers select alternatives that
- Minimize health risks.
- Maximize desirable health outcomes and other benefits
Risk/Risk Assessment
Risk involves the likelihood of experiencing an adverse effect.
Risk assessment refers to
“… a process for identifying adverse consequences and their associated probability”
Steps in Risk Assessment
- Hazard identification
- Dose-response assessment
- Exposure assessment
- Risk characterization
Hazard identification
Examine evidence that associates exposure to an agent with health effects
Produces a qualitative judgment about strength of that evidence
- what types of epidemiological studies have been conducted
- criteria for causality
Dose-response Assessment
The measurement of relationship between amount of exposure and occurrence of unwanted health effects.
- Quantitative relationship between experimentally administered dose level of toxicant and incidence and/or severity of response( typically in animals and applied to humans)
Exposure Assessment
Procedure that:
- identifies populations exposed to risk.
- Describes their composition and size.
- Examines roots, magnitudes, frequencies, and durations of exposure.
Risk Characterization
Estimates of number of excess unwarranted health events expected at different time intervals at each level of exposure
- What is the estimated occurrence of adverse effects in a given population
- Integrates information from three previous steps
- Presents policy makers with summary of all information
Risk management
Oriented toward specific actions, risk management consists of actions taken to control exposures to risk factors in environment
- Ex, Banning of hazardous materials, exposure standards
Worldwide smoke-free Bars laws
Example of policy implementation
First adopted in California
Spread across the United States and eventually to Europe and many countries around the world
- Implemented due to information about the health hazards that secondhand cigarette exposure presented in the work setting.
Health in All policies
Collaborative approach to improve health
Incorporate health considerations into decisions making across sectors and policy areas
Example:
- Health considerations into neighborhood design
Clinical Epidemiology
Focuses on patients and the application of epidemiological methods to assess efficacy of screening, diagnosis and treatment in clinical settings.
Clinical epidemiology asks
Who is most likely to participate in screening and diagnostic testing
how accurate is screening or diagnosis test
if treatment is efficacious, what proportions of patients benefit from treatment
what characterizes those who benefit and those who don’t
how much do patients benefit from treatment
What are risks associated with screening, diagnostic testing, and treatment
What is screening?
Use of tests to help diagnose diseases ( or their precursor conditions) in an earlier phase of their natural history.
Most common purpose is to slow disease’s progress or allow better intervention in a milder disease state
Other uses: employment screening, disease surveillance, protection of society, triage, research
Screening and the Iceberg
Remember the iceberg theory:
- Recognized cases are often only a small part of disease burden
How can we shift the waterline down?
How else is screening beneficial?
Appropriate screening
screening presents complex ethical considerations
Why should we screen for a disease there is no treatment?
should screening be mandatory?what about pre-natal screening?
Who initiates screening? is it voluntary and is there consent?
Screening Guidelines
Lets use diabetes and apply the guidelines to it : EX. A simple fasting glucose can indicate a problem with glucose metabolism
Disease or condition should be a major public health problem:YES
Acceptable treatment should be available :YES
Disease should have recognizable course with identifiable early and latent stages:YES
Suitable and effective test or exam for disease available:YES
Test and testing process acceptable to general population :YES
Natural history of disease adequately understood :YES
Polices, procedures, threshold levels determined in advance:YES
Process simple enough for large groups of people to participate :YES
Evaluation of screening
The ideal test would identify all cases among those screened
- this implies it would also identify all non-cases
So.. it effectively classifies the diseased and the well
Reliability: Precision
Validity: Accuracy( true measure= gold standard)
How to evaluate this?
1: Sensitivity
2. Specificity
3. Positive Predictive power
4. Negative predictive power
What are the four screening result?
True Positive (TP) - Person has disease when in fact they don't
False Positive( FP) - person has disease when in fact they do
False Negative (FN) - Person doesn't have disease when in fact they do
True Negative (TN) - Person does not have disease when in fact they don't
Evaluating Screening
Sensitivity and Specificity represent accuracy of the test
- independent of disease prevalence
PPV and NPV are dependent on accuracy and prevalence of the disease for which you are screening
Lead-Time Bias
Lead- Time: Difference in time between date of diagnosis with screening and date without screening
Also, if lead time is counted in survival time give a misleading picture of benefits of treatment
Length Bias
Slow - progressing cases of disease with a better prognosis more likely to be identified than faster-progressing with poorer prognosis
- cases identified through screening tend to have better prognosis than average of all cases because of length bias
Selection Bias
Choosing nonrandom, non representative data for analysis
- can make test look better/worse in terms of survival
- depends on who gets the test(healthier/ younger vs. high risk)
Over diagnosis Bias
When screening identifies an illness that would not have shown clinical signs before a person’s death form other causes
- prostate cancer example
Mass Screening
Application of screening tests to total population regardless of risk status
Selective screening
- screening applied to high risk groups.
- greatest field of true cases
- what are some examples?
Specificity
d / (b + d)
% of people who do not have the disease were
identified as not having the disease by this screening
test
PPV
a / (a + b)
% of the time a positive identified by this test
was a true positive
NPV
d/ ( c + d)
% of the time this test correctly identified
someone without the disease
Sensitivity
A / (A+C)
Ability of test to correctly
identify those with disease
Ability to correctly identify all screened people who have the disease (%)
