Observational studies and routine data Flashcards
What is an observational study
investigator does not interfere or manipulate exposure e.g case control, cohort
What is an experimental study
investigator determines exposure and who receives intervention e.g randomized control trials
What is the standardised mortality rate
rate ratio adjusted for age. It represents the ratio of the number of observed deaths in a particular population to the number that would be expected (E), if that population had the same mortality or morbidity experience as a standard population, corrected for differences in age structure.
What is the hierarchy of study design
- Systematic reviews and meta analysis
- Randomised controlled trials
- Cohort studies
- Case control studies
- Ecological
- Descriptive
- Case report series
As go up hierarchy studies become more robust and less susceptible to bias
What studies are used to determine accuracy of tests?
cross sectional design
What studies are used to determine disease prognosis?
Cohort study
What studies are used to determine the causes of disease factors
various non-randomised designs
What studies are used to determine population healthcare needs?
various, ecological aggregate studies
What studies are used to determine treatment efficacy
randomised trial
What is routine data?
Routinely collected and recorded in systematic way for administrative or statutory purposes
What are the types of routine data?
Health outcome data, e.g. deaths, hospital admissions and primary care consultations or prescriptions, levels of well-being from national surveys
Exposures and health determinant data, e.g. smoking, air pollution, crime statistics
Disease prevention data, e.g. screening and immunisation uptake
Demographic data, e.g. census population counts
Geographical data, e.g. health authority boundaries,
Births Deaths Cancer registrations Notifications of infectious diseases Terminations of pregnancy Congenital anomalies Hospital admissions Community systems GP consultation data Prescriptions Road Traffic Accidents
What are the advantages of routine data?
- Cheap
- Available
- Standardised collection procedure
- Comprehensive
- Wide range of recorded items
- Available for past years
- Experience in use and intepretation
What are the disadvantages of routine data?
- May not answer all question - not enough detail
- Not every case capitured
- Vairable quality and validity
- Disease labelling may change over time or area
- Coding changes may create artefactual increase or decrease in rates
- Need careful interpretation
What are the uses of routine data?
- Survey: health survey england
- Performance management: quality and outcomes framework for GPs
- Other study design tend to collect own data
Must be careful when looking at changing coding rules
What are descriptive studies?
- Describe distribution of factors or disease in relation to
- May be individual: case reports, case series, cross sectional studies
1. Person (age, sex, etc) 2. Place (variation between countries) 3. Time (variation over time)
What are cross sectional studies?
- Used by healthcare providers to allocate resources
- Can generate clues for hypotheses but not actually give you an answer (need to test in analytical studies)
- Good at describing what people are like with respect to exposure presence or absence
- Don’t know if exposure precede disease
- E.g Health survey for England, 2001 and 2011 census, National Survey of NHS patients
What are the aims of cross sectional studies?
- Annual data about nation’s health
- Estimate population proportion with health condition
- Estimate risk factor prevalence associated with said condition
- Assess frequency of combinations of risk factors
- Examine difference between population sub group
- Monitor targets in health strategy
What core topics are included in cross sectional studies?
- General health and psycho social indicators
- Smoking
- Alcohol
- Demographic and socio economic indicators
- Height, weight, BP
- Use of health services and prescribed medicine
How is mortality measured?
- Death certificates
- Local registrars of birth and deaths
- ONS for coding and processing
- Produced as routinely published tables e.g General DH1, by area DH5, by cause DH2
- Public Health mortality files
How is cancer incidence measured?
- Voluntary notification to local cancer registry
- Also from death certificate
- Useful for both incidence and survival
- Being linked to hospital admission data and national clinical audits
How are infectious diseases measured?
- Look at disease rates
- Reported by doctors to local authority or health protection team
- E.g food poisnoing, meningitis, TB, plague
What is the quality and outcomes framework?
- Component of new General Medical services contract for GPs
- Rewards practices for provision of quality care and helps fund further improvement in delivery of clinical care
- Collected in national database
What is administrative hospital admissions data?
- Counts hospitals admissions
- Episodes: finished consultant episode - time spent under continuous care of specific consultant
- Admission: patient stay in hospital so more than 1 episodes and/transfer between hospitals
- At end of episode can either go home, get transferred or die
How is observed morbidity affected?
- If can’t see GP no one will notice you’re ill and you end up in A and E
- In A and E you might see a junior doctor who will chose to admit you or not
- Might go back home and get worse
- Admission criteria important
