L7 - observational studies and routine data

Question 1

State order of study design hierarchy from best to worst

Answer 1

Systematic reviews + Meta-analyses
RCTs
Cohort 
Case-control
Ecological
Descriptive/cross-sectional
Case report/series

Question 2

Give 3 examples of descriptive/cross sectional studies

Answer 2

National census, NHS health surveys, NHS staff survey

Question 3

What is a descriptive study?

Answer 3

Describes distribution and prevalence of disease/factors in relation to the social demographics of the person (age and sex), places (variation between countries) and the time (yearly/seasonal variation)

Question 4

What is a standard mortality ratio?

Answer 4

A ratio comparing the number of observed deaths (O) in the population to the number of deaths expected (E) in a standard population with the same morbidity/mortality experience and age/sex structure

Question 5

What pieces of data use SMRs?

Answer 5

England and Wales death register 2016

Question 6

What organisation uses descriptive studies stratified by time period?

Answer 6

Office of national statistics

Question 7

List types of routine data

Answer 7

Health outcome data, exposures, health determinant data, demographics, geographical, births, deaths, cancer registration, terminated pregnancy, hospital admissions, infectious disease notifications, road traffic accidents, GP consultation data, congenital abnormalities

Question 8

What are the advantages of routine data?

Answer 8

Cheap, already available, standardised, comprehensive, wide range, archived, easy to interpret and have lots of experience in its interpretation

Question 9

What are the disadvantages of routine data?

Answer 9

May not answer your question, incomplete, not valid, subject to coding changes, variable quality, cannot be used to determine temporal relationship

Question 10

What is the QOF?

Answer 10

Quality and Outcomes Framework

Determines GP salary. Rewards for provision of quality care and helps to fund further improvements.

Question 11

What is the difference between a hospital episode and admission?

Answer 11

Episode = continuous time spent with one consultant
Admission = collection of episodes and prolonged stay

Question 12

What is a case-control study?

Answer 12

Retrospective. Observance of cases and controls from a source population and subdivision to identify the exposed and unexposed so that odds ratios for risk factors can be developed.

Question 13

What bias are case subjects in a case-control study most liable to?

Answer 13

Recall bias

Question 14

What are the advantages of a case-control study?

Answer 14

Good for rare disease, quick, cost efficient, can simultaneously investigate many exposures

Question 15

What are the disadvantages?

Answer 15

Selection bias, recall bias, uncertainty of temporal relationship, poor for rare exposures, cannot calculate incidence directly

Question 16

What is a cohort study?

Answer 16

A group of people that have something in common but are all outcome free are selected at the start. Some are exposed/unexposed, out of these groups some go on to develop the outcome and remain outcome-free.

Question 17

What is relative risk?

Answer 17

Identified by cohort studies. Ratio between number of people in exposed group who got the outcome and number of people in unexposed group without the outcome.

Question 18

What are the advantages of cohort study?

Answer 18

multiple outcomes can be assessed, the natural history of the disease can be followed, good to look at risk, incidence of outcome can be calculated directly, recall bias is minimised

Question 19

What are the disadvantages of cohort study?

Answer 19

insufficient for rare disease, expensive, time-consuming, healthy worker/volunteer effect, loss in follow up