Public Health and PPS Flashcards
KEY Study design: What is a cross-sectional study, a case-control study, a cohort study and a randomised control trial?
What conclusions can be drawn from each (hint 2 and 2)
Cross-sectional studies:
- Snapshot data of those with and without disease to find associations at a single point in time
+ve
- quick and cheap
- large sample size
-ve
- no time reference
- basically they identify associations (odds ratio) but not cause + effect, also revere causality risk
Case-control study:
- it is a retrospective observational study - looks at people that have already have the disease and compares with an analagous group (similar but without the condition), and then look into their exposures and see if their is a difference
- +ve: quick and cheap
- -ve: can show association not causation
Cohort study:
- the oppite of case control, start out with a group of exposed individuals (rather than cases), found an analgous group without the exposure, and follow them to see how the expsoure affects the outcome. Cohort studies can be prospective (data is collected going forward) or retrospective (data from past records is used).
- +ve: better evidence than a case control stidues - can show causation, case control just shows association
- can be used to follow up rare exposures
- ve: expensive and many people may be lost to follow up if disease has a long latent period
Randomised controlled trial:
- A randomised controlled trial (RCT) is an important study design commonly used in medical research to determine the effectiveness of an intervention by randomly assigning participants to either an intevention or control group. It is considered the gold standard in research design because of its ability to minimize bias and establish causal relationships.
+ve:
- good evidence of cause and effect
- comparitive
-ve:
- expensive and time consuming
- ethical issues
Hierachy of evidence: what is the best evidence?
Systematic reviews are above RCT!!! - OMG - was in the 2a paper
Systematic review> RCT> cohort > case-controt> case reports > Expert opinion
KEY - Name 4 theories of behavoir change
- health belief model
- theory of planned behavoir
- transtheoretical/stages of change
- social norms theory
KEY What is the health belief model (6)
Critique
Individuals will change if they:
- Perceived susceptibility- Believe they are susceptible to the condition in question (e.g. heart disease)
- perceived severity - Believe that it has serious consequences
- Perceived benefits of intervention - Believe that taking action reduces susceptibility
- Believe that the benefits of taking action outweigh the costs
2 components were added at a later date:
Cues to Action:
- External or internal triggers that prompt the decision to take action.
- Example: A family member’s illness, a doctor’s recommendation, or public health campaigns.
Self-Efficacy:
- Confidence in one’s ability to take the necessary actions to achieve the desired outcome.
- Example: “I believe I can stick to a healthy eating plan.”
Understanding - an individual will attend breast cancer screening appointment (mamogram) if they believe they are suseptable to breast cancer, that breast cancer is serious, that screening will help and that costs of attending screening are low.
Critique:
▪ Does not consider influence of emotions and environmental constraints - While TPB is effective in predicting intentions (e.g., quitting smoking or exercising), it often struggles to explain the gap between intention and actual behavior due to emotional, habitual, or environmental factors.
▪ Does not account for habits - the model assumes that individuals make health decisions based on logical evaluation of risks and benefits, but it overlooks the influence of habits
THESE ARE THE SAME CRITIQUES!!!
KEY What is the theory of planned behaviour? (3)
Critique
Proposes the best predictor of behaviour is intention e.g. I intend to give up smoking
Intention determined by:
- A person’s attitude to the behaviour
- The perceived social pressure to undertake the behaviour, or subjective norm
- A person’s appraisal of their ability to perform the behaviour, or their perceived behavioural control
ASP
For undestanding:
- attitude- positive and negatives beliefs about behaviour- encompasses many parts of the health belief model.
- subjective norm - motivated to comply with the pressure of social norms, particularly significant others.
- basically self efficacy- whether or not the believe they have the skill, knoweldge, or physical things required to carry out the behaviour)
Application - smoking cessation. attitude - i do not think smoking is a good thing, subjective norm - people who are important to me want me to give up smoking, behavioural control - i believe i have the ability to give up smoking. behaviour intention - i intend to give up smoking
Critique
1. Limited Focus on Habitual Behavior: TPB assumes that behavior is the result of rational decision-making. It does not adequately account for habitual or automatic behaviors, which may occur without conscious intention.
2. Overemphasis on Intentions:While intentions are a strong predictor of behavior, there is often a gap between intention and actual behavior. Factors like emotions, situational constraints, or unforeseen events can derail intentions.
THESE ARE THE SAME TWO CRITIQUES
KEY What is the trans-theoretical/stages of changes model
Critique
Proposes 5 stages of change: pre-contemplation, contemplation, preparation, action, maintenance
PC PAM
- Pre-contemplation – no intention of giving up smoking
- contemplation – beginning to consider giving up, probably at some ill defined time in the future
- Preparation – getting ready to quit in the near future
- Action – engaged in giving up smoking now
- Maintenance – steady non-smoker, ‘i.e. state of change reached
understanding critique - Examines the process of change, rather than factors that determine behaviour, some stages might be skipped
Critique
▪ Not all people move thro ugh every stage linearly
▪ Change might operate on a continuum rather than discrete stages
▪ Doesn’t take into account habits, culture, social and economics - THIS ONE IS THE SAME AS ABOVE
KEY What is the social norms theory?
Critique?
- Human behaviour is affected by what they believe others are doing (the social norm)
- most people misperceive norms among their peers. The norm is positive protective behaviours. They over estimate the risk behaviours and underestimate the protective behaviours.
STEPS:
- identify actual and misperceived norms
- expose people to the actual norm message (intervention)
- person gets a less exaggerated misperceptions of norms
- person engages in less in risky behavoir.
- the real social norms are (data collection) → educate people on what the social norm is.
Background: People dont thnk that the scare tactic will happen to them so they dont work!
Me - critique is basically the same for above ones - emotional, habitual, or structural factors often override rational decision-making.
Hack for Public Health: What two critiques can be applied to basically all four models
- doesnt account for habits - behavoirs arent always the result logical decision making, some things are habitual/automatic
- Over emphasis on Intentions - situational constraints, unforeseen circumstances and emotional influences can prevent people form acting on intention.
These two apply to the 1st three
Trans-theroretical model speciific:
- habbitual stuff above…
- change is continium rather than discreet stages
- might not move through every stage linearly
- more about the process of change rather than facotrs that determine behavoir
Define Health Behaviour, Illness behaviour and Sick-role behaviour?
Health Behaviour: a behaviour aimed to prevent disease (e.g.
eating healthily)
Illness Behaviour: a behaviour aimed to seek remedy (e.g.
going to the doctor)
Sick role Behaviour: any activity aimed at getting well (e.g.
taking prescribed medications; resting)
For Understand- illness vs sick role. Illness behaviour is activity undertaken by someone who feels unwell aimed at getting a diagnosis and find out a remedy. Sick-role - aimed at getting better, so receiving treatment and resting. Basically going to the GP is illness behaviour and taking the prescription is sick roll behaviour.
Why do individuals continued to engage in health damaging behaviour’s when they know they are unhealthy? - One key definition
Name 4 things that influence this reason?
Unrealistic Optimism: Individuals continue to practice health damaging behaviour due to inaccurate perceptions of risk and susceptibility
Perceptions of risk influenced by:
- Lack of personal experience with problem
- Belief that preventable by personal action
- Belief that if not happened by now, it’s not likely to
- Belief that problem is infrequent
Other factors to perception of risk - situational rationality (one extra drink won’t hurt), culture variability, socioeconomic factors, stress….
Define malnutrition
Malnutrition refers to deficiencies, excesses or imbalances in a person’s intake of energy and/ or nutrients.
3 THINGS:
- undernutrition → stunting growth, wasting, underweight, micronutrient deficiences
- overweight + obesity
- hidden hunger - micronutrient deficiency in those that eat enough calories (low income - diet poor in nutrient rich foods)
Identify 4 early influences on eating behavoir and taste preferences?
What term is used to describe conditions in which an infant or young child fails to eat adequately or grow properly due to psychological, social, or behavioral factors rather than a medical or physical causes?
Developing food behaviours:
- Maternal diet (whilst in utero)
- Breastfeeding
- Parenting practices
- age at which introudced to solid foods (The earlier and more diverse the exposure - the less picky when older)
Non-organic feeding disorders (NOFED)
- High prevalence in under 6s
- Feeding aversion, food refusal, negative mealtime interactions
What is restraint theory and what causes it
I wouldn’t say super high yield…
The core idea is that dietary restraint (i.e., consciously limiting food intake) can lead to a pattern of disinhibition (i.e., a loss of control or overconsumption) under certain conditions. When people feel they have already “broken” their dietary rules (e.g., by eating a forbidden food), they may abandon their self-control and binge, because they believe they’ve already “failed.”
Causes:
- paradoxical = increased subjective hunger after dieting (forbidden food becomes more desirable)
- due to imbalance between leptin and ghrelin
- dieting results in loss of lean muscle mass which reduces metabolic rate
- me - food as a coping mechnism for psychological distress
4 dimensions of food insecurity
Dimensions of food insecurity (reducing food intake)
1. Availability: Is there enough food available? Agricultural production and distribution
2. Access: Do people have the resources to obtain it? Affordability? transport infrastructure?
3. Utilization: Are people able to safely and effectively use the food? Cooking appliances?
4. Stability: Is food consistently available and accessible over time?
What are the 5 reasons that can explain an association between an exposure and an outcome?
- Chance
- Bias - an error in how people are selected (selection bias), information is collected between (information)
- Confounding - unmeasured third variable that influences both the exposure and the outcome
- Reverse causality - does obesity cause depression or does depression cause obesity?
- A true causal association
Define Bias?
What is selection bias?
What is information bias and name some different types?
What is publication bias?
Lead time and legnth time bias (involved in screening) are tested elsewhere
Bias may be defined as any systematic error in an epidemiological study that results in an incorrect estimate of the true effect of an exposure on the outcome of interest
- Selection bias - error in how participants are selected or allocated to different groups.
- a systematic difference between those who participate in the study and those who don’t or those in the treatment vs control arms.
- this includes loss to followup and non-response, variables other than the exposure that influence the two groups
- Information bias - collecting the information wrong
- measurement - using different equipment
- observer- the researcher knows which are cases vs control and subconciously measures the outcome differently
- recall - inaccurate memory of events
- reporting - responders are embarassed don’t tell the truth
- Publication bias - positive or significant results are more likely to be published than negative or insignificant results.
What is a confounding factor
A variable other than than those being studied, that infliences both the expsore and the outcome and creates a misleading association between them
Coffee (exposure) → lung cancer (outcome)
Smoking is a confounding factor (people who drink coffee are more likely to smoke). Basicaly The confounder is the actual exposure rather than the one being tested…
what is the Bradford-Hill criteria? (6+/9)
causality - It is difficult to prove that an exposure causes the outcome but the following conditions increase the likelihood of this being the case:
- strength (association is stronger between exposure and outcome than with other outcomes)
- consistency - same result from multiple studies
- dose-repsonse
- temporality - exposure occours before outcome
- Biological plausibility- reasonable biological mechanism, there was a mock question on this!!!
- reversibility - reducing exposure reduces outcome
- coherence - study matches lab studies
- specificity - outcome is specific and not generally better
- analogy - similarity with other cause-effect relationships (valproate with thaladomide which was proven to cause birth defects)
Screening- what is the sensitivity, specificity, positive predictive value and negative predictive value
Sensitivity: [TP/ everyone with the disease (TP+FN)] Proportion of those with the disease who are correctly identified by the screening test (if this is too low, you will miss too many cases)
Specificity: [TN / everyone without the disease (TN+FP)] Proportion of people without the disease who are correctly excluded by the screening test (if this is too low you will have many people who undergo unnecessary diagnostic interventions because they don’t have the disease)
Positive predictive value: [TP/ TP + FP] Proportion of people with a positive test result who actually have the disease (this is higher if the prevalence is higher)
Negative predictive value: [TN/ TN+FN] Proportion of people with a negative test result who do not have the disease (this is lower if the prevalence is higher)
MNEMONIC: OMG
- THE DINOMINATOR IS ALWAYS 2 VARIABLES!!!
- Nominator is always a true value
- the last two have the same letters for all three variable
