ph Flashcards
NRCT Disadvantage
very prone to bias
RCT Disadvantages
Time Consuming
Expensive
Specific inclusion/exclusion criteria may mean the study population is different from typical patients (e.g. excluding very elderly people)
RCT Advantage
Low risk of bias and confounding
Can infer causality (gold standard)
RCT Define
Patients are randomised into groups, one group is given an intervention, the other is given a control and the outcome is measured. Randomisation allows confounding features to be equally distributed.
Types of Observational Study
Types of Experimental/Interventional Study
Observational
Descriptive - case report, ecological
Descriptive and Analytical - cross-sectional
Analytical - Case-control, cohort
Experimental/Interventional
RCT or NRCT
Case Report Description
study individuals
Ecological study Description
use routinely collected data to show trends in data and thus is useful for generating hypotheses. Shows prevalence and association, cannot show causation.
Cross-Sectional Desrciption
Divides population into those without the disease and those with the disease and collect data on them once at a defined time to find associations at that point in time. They are used to generate hypotheses but are prone to bias and have no time reference.
Cross-sectional Advantages
Relatively quick and cheap
Provide data on prevalence at a single point in time
Large sample size
Good for surveillance and public health planning
Cross-sectional Disadvantages
Risk of reverse causality (don’t know whether outcome or exposure came first)
Cannot measure incidence
Risk recall bias and non-response
Case-control description
These are retrospective studies that take people with a disease and match them to people without the disease for age/sex/habitat/class etc and study previous exposure to the agent in question.
Case- control advantages
Good for rare outcomes (e.g. cancer)
Quicker than cohort or intervention studies (as the outcome has already happened)
Can investigate multiple exposures
Case-control Disadvantages
Difficulties finding controls to match with cases
Prone to selection and information bias
Cohort study Description
These studies start with a population without the disease in question and study them over time to see if they are exposed to the agent in question and if they develop the disease in question or not.
Cohort study Advantages
Prospective
Can follow-up a group with a rare exposure (e.g. a natural disaster)
Good for common and multiple outcomes
Less risk of selection and recall bias
Cohort Disadvantages
Takes a long time
Loss to follow up (people drop out)
Need a large sample size
Length Time Bias
Type of bias resulting from differences in the length of time taken for a condition to progress to severe effects, that may affect the apparent efficacy of a screening method
Lead Time Bias
When screening identifies an outcome earlier than it would otherwise have been identified this results in an apparent increase in survival time, even if screening has no effect on outcome.
NPV
the proportion of people with a negative test result who do not have the disease (d/c+d) - this is lower if the prevalence is higher
PPV
the proportion of people with a positive test result who actually have the disease (a/a+b) - this is higher if the prevalence is higher
Specificity
the proportion of people without the disease who are correctly excluded by the screening test (d/b+d)
Sensitivity
the proportion of people with the disease who are correctly identified by the screening test (a/a+c)
Wilson and Jeungner
• The condition
o Important health problem
o Latent / preclinical phase
o Natural history known
• The screening test
o Suitable (sensitive, specific, inexpensive) o Acceptable • The treatment o Effective o Agreed policy on whom to treat • The organisation and costs o Facilities o Costs of screening should be economically balanced in relation to healthcare spending as a whole o Should be an ongoing process
Disadvantages of Screening
- Exposure of well individuals to distressing or harmful diagnostic tests
- Detection and treatment of sub-clinical disease that would never have caused any problems
- Preventive interventions that may cause harm to the individual or population
Types of screening
- Population-based screening programmes
- Opportunistic screening
- Screening for communicable diseases
- Pre-employment and occupational medicals
- Commercially provided screening
Screening Define
A process which sorts out apparently well people who probably have a disease (or precursors or susceptibility to a disease) from those who probably do not. NOT diagnostic.
Prevention Paradox
A preventive measure which brings much benefit to the population often offers little to each participating individual
Population Approach
High risk Approach
- preventative measure eg. dietary salt reduction through legislation to reduce bp
- identify individuals above a chosen cut off and treat – eg. screening for high bp
Types of prevention and define
Primary - preventing disease before it has happened
Secondary prevention – catching disease in the pre-clinical or early phase
Tertiary prevention – preventing complications of disease
Define Epigentics Alostasis Allostatic load salutogenesis Emotional Intelligence
Epigenetics – expression of genome depends on he environment
Allostasis – stability through change, our physiological systems have adapted to react rapidly to environmental stressors.
Allostatic load – long term overtaxation of our physiological systems leads to impaired health (stress)
Salutogenesis – favourable physiological changes secondary to experiences which promote healing and health.
Emotional intelligence – the ability to identify and manage one’s own emotions, as well as those of others
What is primary care for
. Managing illness and clinical relationships over time
. Finding the best available clinical solutions to clinical problems
. Preventing illness
. Promoting health
. Managing clinical uncertainty
. Getting the best outcomes with available resources
. working in a Primary Health Care Team
. Shared decision making with patients
Dangers of overprescribing antibiotics
⋅ Unnecessary side effects
⋅ Medicalise self limiting conditions
⋅ Antibiotic resistance
When to prescribe Ab
⋅ Bilateral otitis media < 2 years old
⋅ Acute otitis media with otorrhoea
⋅ Acute sore throat with 3 or more centor criteria: exudate, fever, tender cervical lymphadenopathy, absence of cough.
⋅ Systemically very unwell
⋅ High risk eg. comorbidities, immunosuppression, ex premature baby
⋅ Aged > 65 and 2 of the following or > 80 and one of the following: hospital admission within last 12 months, type 1 or 2 diabetes, congestive cardiac failure, glucocorticoid use
Which Ab
⋅ Otitis media amoxicillin 500mg TDS 5 days
⋅ Sinusitis amoxicillin 500mg TDS 5 days OR doxycycline 300mg OD day1 then 100mg OD 5 days
⋅ Tonsilitis penicillin V 10 days
⋅ LRTI amoxicillin 5 days
⋅ UTI trimethoprim 200mg BD 3 days OR nitrofurantoin 50mg QDS 3 days
3 domains of PH
Health Improvement, Health Protection and Improving Services
PH Define
The science and art of preventing disease, prolonging life and promoting health through organised efforts of society
Health Improvement
• Concerned with societal interventions (not primarily delivered through health services) aimed at preventing disease, promoting health, and reducing inequalities o Inequalities o Education o Housing o Employment o Lifestyles o Family/community o Surveillance and monitoring of specific diseases and risk factors
Health Protection
• Concerned with measures to control infectious disease risks and environmental hazards
o Infectious diseases
o Chemicals and poisons
o Radiation
o Emergency response
o Environmental health hazards
Improving Services
• Concerned with the organization and delivery of safe, high quality services for prevention, treatment, and care
o Clinical effectiveness
o Efficiency
o Service planning
o Audit and evaluation
o Clinical governance
o Equity
Key concerns
- Inequalities in health
- Wider determinants of health
- Prevention
HNA define
is a systematic method for reviewing the health issues facing a population, leading to agreed priorities and resource allocation that will improve health and reduce inequalities.