Purpose of Survey
The Irish Health Survey (IHS) was collected under Regulation (EC) No 1338/2008 of the European Parliament and of the Council of 16 December 2008 on Community statistics on public health and health and safety at work1. This survey fulfils the need for public health policies to obtain reliable data on health status, health care usage and health determinants.
The Central Statistics Office wishes to thank the participating households for their co-operation in agreeing to take part in the survey, and for facilitating the collection of the relevant data.
The Irish Health Survey was designed in line with the European Health Interview Survey (EHIS)2. The collection of the data under the aforementioned European Regulation implies that harmonised data can be obtained across the European continent.
The Irish Health Survey can be divided into three fundamental components. These are the European Health Status Module (EHSM), the European Health Care Module (EHCM), and the European Health Determinants Module (EHDM).
The European Health Status Module:
The module on health status is a central element of the survey. It allows measurement of the health status of the population in general, and not only in relation to specific health problems. It covers different aspects and dimensions of health: physical and mental health, chronic and temporary problems and specific conditions. It covers the general impact on the functional status and the limitations in activities of daily living of the respondents. The first three general questions on self-perceived health, long standing illnesses or health problems, and activity limitations constitute the Minimum European Health Module (MEHM).
The European Health Care Module:
The ECHM module collects data on the use of health care services and the unmet needs for health care. Information on health care consumption is an essential part of the health information system in order to assign necessary resources to the population. This allows analysis of the relationships between health consumption and several determinants such as health status, lifestyles or socio-demographic characteristics as well as the relationships between different types of health care use.
The European Health Determinants Module:
The general focus of this module is to measure aspects in lifestyles or health-related behaviours. These may have a positive or negative impact on an individual’s health status.
Once collection of the data was completed, it was then combined with selected data from the Quarterly National Household Survey (QNHS). The variables attached were; NUTS3 region, sex, age, nationality, and level of deprivation.
A copy of the Irish Health Survey questionnaire is available here: Questionnaire
This survey was carried out as a module of the Quarterly National household Survey (QNHS). The QNHS is a large-scale, nationwide survey of households in Ireland. It is designed to produce quarterly labour force estimates that include the official measures of employment and unemployment in the state using the International Labour Organisation basis.
A two-stage sample design is used. A new sample was introduced in Q4 2012 following the 2011 Census of Population. The sample frame of households is clustered into blocks (small areas) with each block containing a minimum of 60 occupied households on the night of the 2011 Census of Population. The sample frame is stratified using administrative county and population density. In the first stage 1,300 blocks are selected using Probability Proportional to Size (PPS) sampling and in the second stage 20 households are selected using Simple Random Sampling (SRS). This ensures that each household in the sample frame has an equal probability of selection and results in a total quarterly sample of 26,000 households. The actual achieved sample varies over time depending on the level of response.
Once the second stage of the sampling procedure is complete, a single individual is randomly selected from each household. This individual must be aged 15 years or older. Once selection of the individual is complete, a copy of the questionnaire is left for them to complete and return via post. Alternatively, an option was available whereby the respondent would be directed to a location on the CSO website. The respondent could provide their data securely at this location. There were 10,323 respondents to this survey. Reminders were also issued to respondents after a designated period of time.
The reference period for the survey is 2015. Respondents were sampled from quarter four of 2014, as well as quarters one, two, three and four of 2015, and this sample includes data from each of these quarters.
Grossing and Imputation
The QNHS grossing procedure aligns the distribution of persons covered in the sample with independently determined population estimates at the level of sex, five-year age group and region.
The grossing factors applied in the processing of the Irish Health Survey were calculated in the same manner but differ from those that were used in the preparation of the main QNHS estimates as the Irish Health Survey was asked of a sub-sample of the overall QNHS sample. The grossed population aged 15 years or older is 3,618,544 persons.
Testing was carried out on the sample to investigate if any quarter had a material impact on the results. This was done by removing individual quarters and testing the remainder of the data. On completion of this testing, no statistically significant differences in the results were observed.
Different imputation techniques were used, depending upon the type of variable requiring the imputation. For categorical variables, un-weighted sequential hot deck imputation for global variables was used. This method involves dividing the data into different strata. Data is then selected from observations, and substituted into other observations where that datum is missing.
Regression imputation was used for numerical variables. This technique involves setting the missing value as a dependent variable in a regression equation, and then using correlated variables as the corresponding independent variables. A tendency for imputed values to be located directly on the regression line is avoided by allowing an error rate to be added or subtracted from the imputed value. Zero values were also imputed for missing numerical variables where appropriate. There were low levels of imputation carried out.
NUTS2 and NUTS3 Regions
The regional classifications in this release are based on the NUTS (Nomenclature of Territorial Units) classification used by Eurostat. The NUTS3 regions correspond to the eight Regional Authorities established under the Local Government Act, 1991 (Regional Authorities) (Establishment) Order, 1993, which came into operation on 1 January 1994. The NUTS2 regions, which were proposed by Government and agreed by Eurostat in 1999, are groupings of the NUTS3 regions. The composition of the regions is set out below.
Border Midlands and Western NUTS 2 Region
Southern and Eastern NUTS2 Region
ILO Labour Force Classification
The primary classification used for the QNHS results is the ILO (International Labour Office) labour force classification, and this is also used as an analysis variable for the Irish Health Survey. Labour Force Survey data on this basis have been published since 1988. The ILO classification distinguishes the following main subgroups of the population aged 15 or over:
In Employment: Persons who worked in the week before the survey for one hour or more for payment or profit, including work on the family farm or business and all persons who had a job but were not at work because of illness, holidays etc. in the week.
Unemployed: Persons who, in the week before the survey, were without work and available for work within the next two weeks, and had taken specific steps, in the preceding four weeks, to find work. It should be noted that as per Eurostat’s operational implementation, the upper age limit for classifying a person as unemployed is 74 years.
Inactive Population (not in labour force): All other persons.
The labour force comprises persons employed plus unemployed.
Analysis by deprivation
The Pobal Haase-Pratschke Deprivation Index is used to analyse Irish Health Survey questionnaire responses experienced by individuals. The Index uses Census data to measure levels of disadvantage or affluence in a particular geographical area. More detailed information on the index can be found here: https://www.pobal.ie/Pages/New-Measures.aspx
The results are presented by quintiles, five equal-sized groups of households, with the first quintile representing the least deprived/most affluent area and the fifth quintile representing the most disadvantaged areas.
Diseases and Chronic Conditions
The full list of diseases and chronic conditions which are relevant to Table 4 are as follows:
Faecal Occult Blood Test Definition
The faecal occult blood test is a lab test used to check stool samples for hidden (occult) blood. It can be used to help diagnose certain conditions including, but not limited to, gastric or duodenal ulcers, ulcerative colitis, bowel polyps, and bowel (colorectal) cancer.
Disability Status Definition
Questions ten and twelve of the questionnaire identify various difficulties that individuals may experience. These difficulties are both physical and non-physical in nature. These questions have been used to identify an individual’s disability status. If a respondent has identified ‘a lot of difficulty’ or ‘cannot do at all’ as a response to any of the sub-categories in question ten, the respondent is identified as having a disability. Similarly, if the respondent has identified ‘Quite a bit’ or ‘Extremely’ as a response to question twelve, they are identified as having a disability.
All other responses to these two questions implied that a respondent does not have a disability.
Mental Health Status Definition
The Personal Health Questionnaire (PHQ-8), 8-item depression screener, was selected as the instrument to monitor mental health and it encompasses a subset of the negative mental health dimension – mental health problems. It is an instrument for assessing and monitoring the prevalence and severity of current depressive symptoms and functional impairment and to make tentative depression diagnosis. It is originally derived from the Brief Health Questionnaire, Depression Module (PHQ-9).
Mental health status is calculated using data from question thirteen of the questionnaire. In this question, there are eight items measuring various negative mental health effects experienced in the previous two weeks. Each of these items has four possible answers:
Each of these responses is then given a score; 0 days = 0, 1-7 days = 1, 8-12 days = 2, and finally 13-14 days = 3. The respondent’s scores for each of the eight items are then summed, giving a maximum of 24. The levels of depression are identified by their final score, and the categories are as follows:
Body Mass Index (BMI)
Body Mass Index (BMI) is a simple index of weight-for-height that is commonly used to classify underweight, overweight and obesity in adults. It is defined as the weight in kilograms divided by the square of the height in metres (kg/m2).
In the European Health Interview Survey, four BMI categories are present. These are;
Binge drinking is defined by health experts, such as the World Health Organisation (WHO), as six or more standard drinks in one sitting, which is the equivalent of three or more pints of beer or six or more pub measures of spirits.