Date post: | 15-Nov-2014 |
Category: |
Education |
Upload: | south-west-observatory |
View: | 1,038 times |
Download: | 2 times |
South West Public Health Observatory
Key Data Sources for Public Health Public Health Information and Evidence Seminar
Mark Dancox
4th November 2010
South West Public Health Observatory
In this session
• Main sources of data used in Public Health
• Over-view of special methods used to measure the health of a population
• Specific data sources for the South West
South West Public Health Observatory
First things first
• In public health we are often interested in the frequency, distribution and determinants of health problems and disease in populations.
• The unit of interest is the POPULATION not the individual.
South West Public Health Observatory
What data do we use?
• Raw data, only available to NHS employees with appropriate role-based permissions:– Births – Deaths – Hospital Admissions– Cancer Registrations– GP consultations – Prescriptions – A&E attendances– Population
• Need to aggregate data so that it can’t be identified
South West Public Health Observatory
What’s the distribution?
• Often want to tie in frequency information to location. • Consideration of geography is therefore important:
– Postcode– Lower Super Output Area– Local Authorities – Primary Care Trusts– Strategic Health Authorities
• Need to link geography information to births and deaths data
• Social Marketing datasets linkage
South West Public Health Observatory
• Mortality – All cause– Specific cause– Place of death
• Life Expectancy – General measure of health– At birth – Disability Free
• Births– Birth Rate – Infant Mortality
Some common types of measures:
South West Public Health Observatory
– Widely accepted system of classifying diseases and causes of death developed by the World Health Organisation.
– Updated every 10 years or so to keep up with advances in medical knowledge and improvements in methods of diagnoses.
– Changes in coding can present problems when looking at the occurrence of specific causes of death through time.
– ONS regularly produce data on mortality statistics using the ICD-10 system.
ICD-10
South West Public Health Observatory
– Infectious and parasitic diseases– Neoplasms– Diseases of the blood and blood forming organs– Endocrinal and Nutritional diseases– Mental and behavioural disorders– Diseases of the circulatory system– Diseases of the respiratory system– Injury, poisoning and certain other causes of external
consequences
ICD-10 Headings include:
South West Public Health Observatory
Hospital Admissions (HES)
• Principal source of data on all admissions to NHS hospitals in England.
• Data warehouse containing details of all admissions to NHS hospitals in England.
• Includes private patients treated in NHS hospitals, patients who were resident outside of England and care delivered by treatment centres (including those in the independent sector) funded by the NHS.
• Contains details of all NHS outpatient appointments in England
South West Public Health Observatory
Determinants : Factors affecting health• Health is affected by many factors, as summarised by
Dahlgren and Whitehead’s diagram…
South West Public Health Observatory
What are the determinants ?
• Age, sex and constitutional factors• Lifestyle • Agriculture and Food production• Education• Work Environment• Unemployment• Water and Sanitation• Health Care Services• Housing
South West Public Health Observatory
Deprivation
• Prepared by DCLG• Area based measure based on seven ‘domains’
– Health and Disability– Income – Employment – Education skills and Training– Barriers to housing and services– Crime – Living Environment
• Applies to England• IMD2004 and IMD2007 available
South West Public Health Observatory
Surveys
• Established surveys can provide information on the determinants of health– Health Survey for England– General Household Survey– Longitudinal Study– Active People – National Child Measurement Program
South West Public Health Observatory
Health Survey for England
• Annual • Questionnaire-based answers with physical measurements
and analysis of blood samples. • Blood pressure, height and weight, smoking, drinking and
general health are covered every year.• An interview with each eligible person in the household is
followed by a nurse visit.
South West Public Health Observatory
General Household Survey
• Information from people living in households in England • Annual • Data collected on
– household and family information – housing tenure and household accommodation – consumer durables including vehicle ownership – employment – education – health and use of health services – smoking and drinking – family information including marriage, cohabitation and fertility – income – demographic information about household members including
migration.
South West Public Health Observatory
South West Observatory Modules
• Further information on the determinants of health can be found via the modules of the South West Observatory:– Economy– Skills and Learning– Planning – Environment– Crime – Culture
• State of the South West
South West Public Health Observatory
Special methods of measuring public health• Published sources of Public Health data use different
methods of measuring the health of a population:– Incidence – Prevalence – Crude Rate– Standardised Rates – (confidence intervals)
South West Public Health Observatory
Prevalence
Prevalence quantifies the proportion of individuals in a population who have the disease at a specific instant.
Total number of cases at a given timePrevalence = Total population at that time
Note: No time period is involved here.
South West Public Health Observatory
Incidence
Incidence quantifies the number of new cases of disease that develop in a population of individuals at risk during a specified time period.
Number of new cases in period of timeIncidence =
Population at risk
The denominator, “population at risk” , should consist of the entire population in which new cases can occur.
Incidence and prevalence
Sick population
(Prevalence)Healthy
population
Incidence (new cases)
die (mortality)
recover
South West Public Health Observatory
Crude Rate
• Is the number of cases in a population divided by the total population during a specific time interval.
• Provides information on the experience of the population.
• Useful for the allocation of health resources and public health planning.
• However if comparing heart disease rates between two populations where one population had a larger proportion of young people then differences in rates might simply reflect the relationship between heart disease and age.
South West Public Health Observatory
Category-Specific Rates
• To account for different population distributions of a factor of interest we can present and compare category-specific rates.
• These are calculated on a subgroup of the population which is defined by stratifying the populations into categories e.g age.
• They permit comparisons between different categories within the same population.
South West Public Health Observatory
Age standardisation
• Occurrence of disease in one area may appear to be higher than in another because:– Population structures are different– One area is older than another
• Standardisation used to adjust for the effects of age on mortality rates or other rates
• Direct or Indirect• Involves the calculation of numbers of expected
events which are then compared with numbers of observed events
South West Public Health Observatory
Two Methods of standardisation
• Different methods available but ‘Direct’ and ‘Indirect’ methods are most common
• Can calculate confidence intervals for each• Which method used depends on the comparisons to be
performed and the availability of data
South West Public Health Observatory
When to use which?
• No right or wrong approach, but…– Direct standardisation useful to compare different areas
or through time– Indirect Standardisation useful to determine if disease
incidence is high or low in one area.
South West Public Health Observatory
Measures in action….Health Profiles
South West Public Health Observatory
Measures in action….NCHOD