3.1 Health and Disease: Public Health & Health Promotion
Practical 2: Population health assessment
Learning Objectives
Course objectives
Describe the main health problems experienced by populations and groups within them
Distinguish between different measures of health and disease
Describe health services organisation
Consider the options for investigation of a health problem in a population
Apply epidemiological principles and methods to medical practice
Explore the role of public policy in health
Practical objectives
By the end of this practical session students will be better able to:
- describe the issues involved in assessing the health of a population
- describe processes of assessing the healthcare needs of populations
- understand the concepts of need, demand and use
2.1 We need to assess population health and health care needs to develop policy, plan services, and allocate resources.
1. How can we measure health?
Prevalence is defined as the number of affected persons present in the population at a specific time divided by the number of persons in the population at that time.
Prevalence per 1,000 =
No. of cases of a disease present in the population at a specified time X 1,000
No. of persons in the population at that specified time
The incidence of a disease is defined as the number of new cases of a disease that occur during a specified period of time in a population at risk for developing the disease.
Incidence per 1,000 =
No. of new cases of a disease occurring in the population during a specified period of time X 1,000
No. of persons at risk of developing the disease during that period of time
Options for comparing frequency of health/disease states, risk factors:
2. How can we measure healthcare needs?
Revise need = capacity to benefit
Felt need (can be measured) vs unfelt need (cannot be except from through screening)
Met need vs unmet need
Role of clinical/professional judgement: need for healthcare
Normative need – depends on judgment of professionals
3. What factors influence demand for healthcare?
Demand = expressed need
Felt need
Illness behaviour
Supply/availability of services.
4. How can we measure prevalence of a condition?
Cross sectional surveys
Analysis of routine data
SMRs
Surveillance, Registers
5. How can we measure incidence of a condition?
Hospital data – new episodes: HIPE in Ireland (coding issues)
Primary care data
Surveillance, Registers
2.2 Mortality
6. Where do mortality data come from?
Death certificates: who completes them?
Coding issues: International Classification of Diseases version 10
Who does coding – trained coders who are clerical staff
A 49 year old woman was attending a wedding. She complained of a headache and within 3 hours became disoriented and collapsed. Emergency services were called. She was transferred to the local Accident & Emergency Department where she was pronounced dead on arrival. She had a diagnosis of breast cancer 5 years earlier. Her husband described how she had been intermittently disoriented in the previous 4 months and had been on anti-hypertensive treatment for the previous 10 years. An autopsy was conducted, describing cause of death as cerebral haemorrhage with evidence of brain metastases and malignant breast cancer.
7. You are the woman's GP. Complete the Death Registration Form. (See Appendix)
Refer to handout from CSO AFTER you have attempted to complete form.
Note that this could be a coroner's case as the woman died on arrival in hospital and may not have been seen by a doctor for some time (this will be considered in Forensic Medcine)
8. Discuss the issues associated with reliability and validity of death certificate data.
Errors in completing death certificates, validity of final clinical diagnosis with and without post-mortem examination, errors in coding death certs, changes in coding ICD-9 vs. ICD-10 etc.
Consider how this affects mortality data
9. How can the information from death certificates be used to plan services?
Death certificates go from the Registrar of Births, Marriages and Deaths to the Central Statistics Office.
Population based deaths rates from various conditions are calculated and used nationally / regionally to
- assess the extent of health/disease problems,
- develop policies and services to address these problems,
- evaluate the effectiveness of policies/services in addressing problems.
National data is shared with EU/WHO for international comparisons.
10. Discuss the importance of standardised mortality ratios and how they are calculated.
When examining mortality data in particular comparing two or more populations, or one population in different time periods, such populations may differ in regard to many characteristics that affect mortality, of which age distribution is the most important as it is the single most important predictor of mortality. Therefore standardizing mortality is a method applied in order to compare mortality while effectively holding age constant.
Direct Standardisation: A standard population is used in order to eliminate the effects of any differences in age (EU standard population)
Indirect standardisation: used in two circumstances in particular
when age strata are not available
when small population analysis is carried out e.g. occupational groups
SMR = observed x 100
expected
2.3 Population Health Assessment
Health status assessment: to identify, scope, characterise and quantify health issues or problems experienced by a specified population.
Health needs assessment: to determine and implement the optimal local solution to a specified population health issue or problem, on the basis of robust evidence, feasibility, stakeholder input and available resources.
Health care assessment: to evaluate existing services and to identify potential quality improvement though redesign, modification, or development.
Health Impact Assessment: a combination of procedures, methods and tools by which a policy, programme or project may be judged as to its potential effects on the health of a population and the distribution of those effects within the population
All require detailed information on health and health needs.
10. How do you think you would assess the need for, for example, breast cancer services in this region?
Note that needs assessment requires careful planning
Epidemiological approach to health needs assessment
Combines specific health status assessments with assessment of the effectiveness of potential interventions
- Incidence and prevalence
- Effectiveness and cost-effectiveness
- Existing services
What is the size and nature of the problem?
We want to know how many people are likely to be suffering from the condition, their characteristics (who/what/where/when etc), to what extent are they already receiving appropriate treatment/management (refer to guidelines if they exist)
- Incidence: National Cancer Registry
- Prevalence: consider sources of routine data such as SMRs from CSO, hospital activity from HIPE; if a prevalence study is needed possibly a questionnaire survey of population or of GPs
- Effectiveness and cost-effectiveness: Cochrane library, Effective Health Care Bulletins, UK's National Institute of Health and Clinical Effectiveness (NICE), specialised studies.
- Describe existing services: identify and describe services and interventions being delivered
Comparative needs assessment: contrast levels of services received by one population with other populations and with standards
The guidelines for the management of breast cancer from both the Royal College of Surgeons in Ireland and England are on Blackboard: these include for instance that multidisciplinary teams form the basis for best practice in the management of breast cancer; estimates of the surgical workload of a breast cancer unit; recommendations on treatment, staffing, appointment times, audit, quality standards, screening; training and education etc.
Corporate needs assessment: includes the views on demands and wishes of patients, carers, professionals, politicians, voluntary organisations and others.
Consider how to seek these views: consultation processes. Surveys, interviews, meetings, focus groups etc.
What are resource implications?
Costs, human resources, facilities etc
Competing priorities?
Appendix: Practical 2
