population health

Question 1

what is bells palsy?

Answer 1

A sudden, one sided, idiopathic, facial nerve (lower motor neuron) paralysis.
About 1/3 acute peripheral facial weakness caused by trauma, the Ramsay Hunt syndrome (Varicella Zoster),
Lyme disease, sarcoid, parotid gland tumour. Other 2/3 idiopathic “Bell’s Palsy”
Cause unclear. UK incidence 1 in 5000/yr. Mainly 15-60 year olds.

Question 2

what is the clinical diagnosis of bells palsy?

Answer 2

Facial weakness develops in 2 days. Earache or facial pain may precede palsy.
Confirm unilateral, lower motor neuron lesion.
Facial expression muscles affected - drooping brow & mouth, weak forehead muscle & unable to close eye.

Question 3

what is the difference between upper motor neurone (central eg. stroke) and lower motor neurone (peripheral e.g balls palsy)

Answer 3

central facial palsy

• preservation of forehead & brow movements
• loss of nasolabial folds & drooping of the lower lip

peripheral facial palsy:

• loss of forhead & brow movements
• inability to close eyes & drooping of eyelids
• loss of nasolabial folds and drooping of the lower lip

Question 4

what is the management of bells palsy?

Answer 4

Advice:
Prognosis good: most recover fully within 9 months.
Keep eye lubricated- eye drops in day, eye ointment at night & tape eye closed at night if can’t close

Drugs:
If present <72 hrs of symptoms, prednisolone eg 25 mg twice daily for 10 days
Antiviral treatments not recommended.
Evidence based on two large RCTs in Cochrane review Sullivan et al 2007, Engstrom et al 2008
No evidence for physiotherapy

Question 5

When should you refer someone with balls palsy to secondary care?

Answer 5

Urgently to neurology or ENT if: doubt regarding diagnosis, recurrent or bilateral Bell’s palsy.
If cornea exposed after attempting to close eyelid, refer urgently to ophthalmology.
If no improvement after 1 m, or suspect underlying diagnosis (e.g. cholesteatoma, parotid tumour, malignant
otitis externa), refer urgently to ENT.
If paralysis after 6–9 m refer to plastic surgeon

Question 6

what is epidemiology?

Answer 6

the study of how often diseases occur in different groups of people and why

Question 7

what does ‘burden of disease’?

Answer 7

Description of death and loss of health due to diseases, injuries and risk factors for all regions of the world.

Question 8

what is the definition of ‘incidence’?

Answer 8

proportion of an initially disease-free population that develops disease during a specified period of time

Question 9

what is the definition of prevalance?

Answer 9

proportion of the population who have a particular disease over a specified period of time

Question 10

what is the definition of a ‘clinical iceburg’

Answer 10

the cases of a condition that are diagnosed (for certain conditions there
are often many undiagnosed cases)

Question 11

what 4 topics are involved in population health data?

Answer 11

chronic disease - acute illlness
interface with secondary / community / social care
consulations in primary care
burden of disease

Question 12

what are the care pathways from primary care?

Answer 12

1. Secondary care
2. Community healthcare
3. social care

Question 13

what are the different types of preventions, their actions, and their outcome on disease?

Answer 13

Primary

• action: remove cause of disease
• Outcome on disease: reduce occurence (incidence) of disease
  examples: immunisation, lifestyle advice.

Secondary

• action: screening for early disease
• outcome: early intervention giving improved prognosis; less radical treatment.
  examples: screening (antenatal - infection screening, bp check, diabetes, adolescence - sexual health, mid life - qrisk, qof, risk factors)

Tertiary

• action: treatment of established/ late disease
• outcome: Manage consequence of disease; prevent complications or recurrence.
  example: chronic disease management ( young adults - mental health, mid life, older adults - frailty, polypharmacy)

Question 14

What are the current approaches for routinely collected data?

Answer 14

1. Quality and Outcomes Framework (QOF)
2. Primary Care Databases used for research e.g. QResearch / CPRD / OpenSAFELY (COVID-19)
3. Other National Data Resources such as NHS Digital / Office of
   National Statistics

Question 15

What are the commonly used research methods available in primary care?

Answer 15

Hierarchy of evidence
•Cross-sectional studies
•Cohort studies
•RCTs
•Systematic reviews and meta-analyses
•Qualitative research
•Applications in primary care and impact on public health policy

Question 16

Why do we do research in primary care?

Answer 16

• Evidence based medicine
• Improve patient care and outcomes
• Quality, effectiveness, cost-effectiveness
• Question current practice & generate new ideas

Question 17

How can you translate research into practise?

Answer 17

Systematic Review, Meta-analyses
• Cochrane reviews
• NICE / SIGN Guidelines

Question 18

What is the evidence hierarchy?

Answer 18

‘pyramid’ of evidence types for treatment benefit.
Note that the level of evidence may be graded down on the basis of:
• Study quality
•Imprecision (wide confidence intervals)
• Indirectness (an imperfect match between the PICO* of interest and the PICO* of the study)
• Inconsistency between studies,
• Small absolute effect size

Question 19

what does PICO(S) framework stand for?

Answer 19

used to frame and answer a clinical or healthcare related question.      
P - patient, problem or population
I - Intervention
C - Control, comparison, comparator
O- Outcome
S- Study design

Question 20

what are the levels of the evidence hierarchy?

Answer 20

Level 1: Systematic review of RCTs
level 2: Randomised trial or observational study with dramatic effect
Level 3: Non-randomised controlled cohort /
follow-up study
Level 4: Case-series, case-control studies or historically controlled studies
Level 5: mechanism-based reasoning (from non-clinical studies, eg in vitro)

Question 21

What are some advantages of population surveys?

Answer 21

Cross-sectional sample of the general population served by primary care
•Simplest type of epidemiological study
•Taken at one point in time (snapshot)
•Provides information needed to take important public health decisions
•Information can be gathered about outcomes (eg. diseases, infections) or
exposures (eg. smoking, alcohol intake) or relationship between them
(but associations only, not causal).
•Measures prevalence

Question 22

What are some examples of cross sectional studies in primary care?

Answer 22

•Annual Survey since 1991
-Monitors changes in health and lifestyle
-Planning services
-Policy development and evaluation
- Provides National data which can be compared against local figures
•Questions about health and lifestyle of a sample of people in the UK
•Approximately 8000 adults and 2000 children
•Information from interview and a nurse visit

Question 23

What is cohort studies?

advantages? disadvantages?

Answer 23

A group of healthy people defined by their exposure status are followed up over time
Advantages:
• Can assess multiple outcomes
• Exposure occurs before outcome, allowing causal inference
• British Doctors Study (1951) the world’s first large prospective cohort study to establish a link between the effects of smoking and cause-specific mortality and lung cancer (also showed increased cardiovascular events).

Disadvantages:
time consuming
expensive
prone to bias due to losses to follow-up.

Question 24

Example of cohort studies in primary care

Answer 24

CPRD (clinical practice research datalink)
• UK General Practice Database
• 7% of the population
• Uses routinely collected anonymised GP data
• Quicker and cheaper than constructing a cohort and following them up over time
• Limitations: May not provide information on variables of interest, quality of data linkage, issues with patient coverage & variability in quality of information collected
• Examples eg HRT as exposure with outcomes either DVT/PE or different cancers or cardiovascular outcomes
• Example on next slide using CPRD to examine diabetes and infection risk in primary care

Question 25

why are RCTS the gold standard design (advanatges)?

Answer 25

• An RCT can test a causal hypothesis or evaluate the efficacy
of an intervention
• Randomisation minimises allocation bias and selection bias
• Blinding minimises performance bias and double blinding
minimises assessment bias
• Randomisation removes known and unknown confounders
(variables which
can interfere with the studied association)

Question 26

what are the disadvantages to RCTs?

Answer 26

•Ethics of randomisation: the need for clinical equipoise
•RCT patients may be different from the target population – so issues of
generalizability of results
•Expensive to run and take a long time (risk loss of relevance, as practice
may have moved on)
•May focus on short term proxy endpoints rather than long term effects
•Difficult to detect rare or long-term adverse effects
•If there are significant losses to follow-up this can bias results.

Question 27

Systematic reviews and meta analyses

Answer 27

• Summary of available data
• Evaluate and decide on most effective practice
• Assess quality of existing evidence eg Cochrane collaboration
• Usually RCTs but can do SR and MA of other studies
• Findings usually presented in a Forest plot
• Each line represents a single study (estimate and 95% confidence intervals)
• Diamond shaped summary estimate at bottom

Question 28

What are qualitative studies?

Answer 28

• Important field of research but not included in hierarchy of evidence
• Doesn’t answer the question of whether an intervention works or not, but helps to understand questions like why or how it works or who it works for
• Hypothesis generating
• ‘Listening to the patient’s (or participant’s) voice.’
• Semi-structured interviews
• Focus group and 1:1 interviews
• Data analysis: transcripts are studied to identify concepts and relationships. Thematic analysis