NSW Population Health Survey (SAPHaRI). Centre for Epidemiology and Evidence, NSW Ministry of Health.
The indicator shows self-reported data collected through Computer Assisted Telephone Interviewing (CATI). Estimates were weighted to adjust for differences in the probability of selection among respondents and were benchmarked to the estimated residential population using the latest available Australian Bureau of Statistics mid-year population estimates. Adults are defined as persons aged 16 years and over in the NSW Population Health Survey.
In order to address diminishing coverage of the population by landline telephone numbers (<85% since 2010), a mobile phone number sampling frame was introduced into the 2012 survey.
LL/UL 95%CI = lower and upper limits of the 95% confidence interval for the point estimate.
The NSW Ministry of Health has conducted the Adult Population Health Survey (since 1997) and the Child Population Health Survey (since 2001) through the New South Wales Population Health Survey, an ongoing survey of the health of people in NSW using computer-assisted telephone interviewing (CATI). The main aims of the surveys are to provide detailed information on the health of adults and children in NSW and to support planning, implementation and evaluation of health services and programs in NSW.
The survey instruments include question modules on health behaviours, health status, and other associated factors. The methods and all questions are approved for use by the NSW Population and Health Services Research Ethics Committee. While some questions are collected annually, other questions are collected less frequently. The instrument is translated into 5 languages: Arabic, Chinese, Greek, Italian and Vietnamese.
The target population for the survey is all state residents living in private households. The target sample was approximately 1,000 persons in each of the health administrative areas (total sample 8,000-16,000 depending on the number of administrative areas).
From 1997 to 2010 the random digit dialling (RDD) landline sampling frame was developed as follows. Records from the Australia on Disk electronic white pages (phone book) were geo-coded using MapInfo mapping software. The geo-coded telephone numbers were assigned to statistical local areas and area health services. The proportion of numbers for each telephone prefix was calculated by area health service. All prefixes were expanded with suffixes ranging from 0000 to 9999. The resulting list was then matched back to the electronic phone book. All numbers that matched numbers in the electronic phone book were flagged and the number was assigned to the relevant geo-coded area health service. Unlisted numbers were assigned to the area health service containing the greatest proportion of numbers with that prefix. Numbers were then filtered to eliminate continuous non-listed blocks of greater than 10 numbers. The remaining numbers were then checked against the business numbers in the electronic phone book to eliminate business numbers.
From 2011 onwards the RDD landline sampling frame was developed as follows: Australian Communications and Media Authority exchange district and charge zone prefixes were generated for each of the strata (that is Local Health Districts introduced in January 2011) using “best fit” postcode (ACMA 2011). All prefixes were expanded with suffixes ranging from 0000 to 9999. The sample was then randomly ordered within each stratum. The estimated numbers required for each stratum was then forwarded to Sampleworx, who used proprietary software to test each numbers current status (valid, invalid or unknown and business, non-business or unknown). The resulting valid non-business and valid unknown numbers were used for the survey.
From 2012 onwards mobile only phone users were included into the surveys using an overlapping dual-frame design, which incorporates three groups of respondents: landline only users, mobile only users and landline and mobile users.
The RDD mobile sampling frame was developed by Sampleworx and included using all known Australian mobile prefixes. Sampleworx used proprietary software to test each number to identify valid and invalid numbers. A random sample of valid mobile numbers was then provided for use for the survey.
The introduction of this design was prompted by the increasing numbers of mobile-only phone users in the general population. Because this design increases the representativeness of the survey sample the production of unbiased estimates over time is also improved. This improvement has been confirmed by an analysis of unweighted estimates, which indicated that a greater proportion of younger people, of males, and of people born overseas participated in the mobile sample compared with the landline sample. Further, comparison of the demographic characteristics of the survey sample for the first quarter of 2012 with the NSW population showed that the NSW Population Health Survey was more representative of the NSW population than the previous sample (Barr et al. 2012).
Due to this change in design, the 2012 NSW PHS estimates reflect both changes that have occurred in the population over time and changes due to the improved design of the survey.
When considering significant differences over time excluding the 2010 and 2011 data points ensures that all of the estimates are from sampling frames that had adequate coverage of the population, that is 85% or more.
When the Australia on Disk electronic white pages became available, reliable introductory letters were sent to the selected households (1997 to 2008). Households were contacted using random digit dialling. Depending on the frame either one person from the household was randomly selected or the mobile phone holder was selected for inclusion in the survey.
Interviews are carried out continuously between February and December each year. An 1800 freecall contact number and website details are provided to potential respondents, so they can verify the authenticity of the survey and ask any questions regarding the survey. Trained interviewers at the Health Survey Program CATI facility carried out interviews until the end of 2014. For 2015, the NSW Population Health Survey was outsourced to McNair Ingenuity Research Pty Ltd, which is a social and market research company. All protocols related to the collection of respondent data have been implemented by McNair.
Up to 7 calls are made to establish initial contact with a household, and up to 5 calls are made in order to contact a selected respondent. Respondents reached by a landline phone number undergo a within-household selection process, where each member of the household has an equal chance of selection for interview. Respondents reached via mobile phone do not undergo this household selection process. Where a child under the age of 16 has been chosen within the household, the parent or main carer for that child completes the interview on their behalf. When an adult respondent that lives in a household with a child or children is selected for interview, at the end of their interview, they are offered to opportunity to complete a secondary interview about one of their children. In 2015, approximately 41% of all primary adult respondents living in households with at least one child under the age of 16 took up this option. If a parent completing an interview about their children is unsure of their child’s height and/or weight, the respondent is offered the opportunity to be contacted at a later date for this information.
For analysis, the survey sample was weighted to adjust for differences in the probabilities of selection among respondents. Post-stratification weights were used to reduce the effect of differing non-response rates among males and females and different age groups on the survey estimates. These weights were adjusted for differences between the age and sex structure of the survey sample. Population data based on Australian Bureau of Statistics estimates and population projections based on data from the NSW Department of Planning and Infrastructure have been used to calibrate weights to the population within each health administrative area. and the Australian Bureau of Statistics latest mid-year population estimates (excluding residents of institutions) for each health administrative area.
Call and interview data were manipulated and analysed using SAPHaRI and SAS version 9.4 (SAS). The Taylor series expansion method was used to estimate sampling errors of estimators based on the stratified random sample. The 95 per cent confidence interval provides a range of values that should contain the actual value 95 per cent of the time.
Estimates were smoothed using least-squares spline transformation (CEE, Adult survey methods: web page).
Further information on the methods and weighting process is provided elsewhere (CEE, Child survey methods: web page).
A proportional hazard regression model with time equal to one unit using PROC SURVEYREG in SAS software was fitted. PROC SURVEYREG produces relative risks while taking into account the complex survey design; the strata and weights. The strata are a combination of Local Health District and year. The weights are based on the probability of selection in the survey and the age and sex structure of the population each year. For trend analysis, the weights are recalibrated to te 2001 Australlian Standard Population by five year age groups to age standardise the analysis. Age-sex standardisation was implemented across the complete survey file (both adult and child records). Separate models were fitted for each sex, and each model had year as the independant variable and the binary indicator as the dependant variable.
Estimated annual rates of change for health indicators (and associated 95% confidence intervals) were calculated from these models as relative differences. If the confidence intervals for the relative difference did not overlap a value of 1, the change was considered statistically significant.
In the reporting of trend analysis results on the topic landing page data summary tables (such as http://www.healthstats.nsw.gov.au/IndicatorGroup/ChildObesityTopic ), up and down arrows are used to show statistically significant increasing and decreasing annual rates of change. If the rate of change is not statistically significant, the trend is considered stable as illustrated by horizontal arrows. For statistically significant trends, the percentage point difference between modelled prevalence for the most recent year of data and that for 5 (short term trend) or 10 years (long term trend) prior. The short term percentage point difference is based on the model incorporating the 5 most recent years of data. The long term trend analysis is based on the model incorporating yje 10 most recent years of data. For context, the raw prevalence (and associated 95% confidence interval) estimated from the survey for the most recent year is also reported in the data summry tables.
Australian Bureau of Statistics. Standard Population for Use in Age-Standardisation Table (Cat. no. 3101.0), 2013
Australian Communications and Media Authority (ACMA). Communications report 2010-11 series: Report 2 – Converging communications channels: Preferences and behaviours of Australian communications users. Commonwealth of Australia, 2011. Available at http://www.acma.gov.au/
Barr ML, Ritten JJ, Steel DG, Thackway SV. ‘Inclusion of mobile phone numbers into an ongoing population health survey in New South Wales, Australia: design, methods, call outcomes, costs and sample representativeness’. BioMed Central: Medical Research Methodology 2012, 12:177 (22 November 2012). Available at www.biomedcentral.com/1471-2288/12/177.
Centre for Epidemiology and Evidence. NSW Adult Population Health Survey Methods. CEE, NSW Ministry of Health. Available at http://www.health.nsw.gov.au/surveys/adult/Pages/default.aspx
Centre for Epidemiology and Evidence. NSW Child Population Health Survey Methods. CEE, NSW Ministry of Health. Available at http://www.health.nsw.gov.au/surveys/child/Pages/default.aspx
PitneyBowes Software. MapInfo (software). PBS as MapInfo Corporation: version 1997. Available at www.pbinsight.com.au
Sampleworx Pty Ltd. Available at http://www.sampleworx.com.au
SAS Institute. The SAS System Enterprise Guide version 7.15 (software). Cary, NC: SAS Institute Inc., 2017. Available at www.sas.com
United Directory Systems. Australia on Disk (software). UDS: version 2004. Available at www.uniteddirectorysystems.com
Influenza immunisation significantly reduces morbidity and preventable mortality. It is recommended and nationally funded for all people aged 65 years and over, Aboriginal and Torres Strait Islander people aged 6 months to less than 5 years and 15 years and over, pregnant women, and people aged 6 months or over with conditions predisposing to severe influenza. In 2018, NSW funded influenza vaccination for all children aged 6 months to less than 5 years. Influenza vaccination needs to be given each year.
The indicator includes those aged 65 years and over who have been immunised against influenza in the previous 12 months. In 2018, two new influenza vaccines that offer increased protection to people aged 65 years and over were introduced onto the National Immunisation Program.
The question used to define the indicator was: Were you vaccinated or immunised against flu in the last 12 months?
Influenza and pneumonia are a group of acute respiratory infections that can be very severe and, in persons at high risk, lead to death. They are usually presented together as influenza can lead to pneumonia and, in most cases of hospitalisation and death from pneumonia, the responsible organism is not identified. Each year, 75-85 % of all hospitalisations for influenza and pneumonia are due to 'unspecified pneumonia'.
Severe virus-related complications of influenza require hospitalisation and threaten life most frequently in the very young and elderly (children under 1 year old and persons over 65) and among persons with chronic heart or, especially, lung conditions. Appropriate antibacterial therapy decreases the mortality rate from secondary bacterial pneumonia.
Annual influenza vaccination is recommended for any person aged ≥6 months who wants to protect themselves from influenza and is strongly recommended for groups at higher risk of disease.
There were 34,771 hospitalisations due to influenza and pneumonia in 2018-19 (372.4 per 100,000 population), of which 19,909 were patients aged 65 years and older (1477.2 per 100,000 population in that age group).
There were 951 deaths from influenza and pneumonia in 2018 (8 deaths per 100,000 population) and just over 92% of these were in persons aged 65 years and over (57.4 deaths per 100,000 population in that age group). Death rates from influenza or pneumonia are very low in all other age groups. The death rate in 2009 was the lowest since 1998 for all ages and for people aged 65 years and older.
Respiratory diseases include acute diseases such as influenza and pneumonia, and chronic respiratory diseases (specifically asthma, chronic obstructive pulmonary disease, asbestosis, and respiratory tuberculosis), where preventive measures and better management of conditions can reduce the burden of disease and reduce associated healthcare costs.
Chronic respiratory diseases were responsible for 7.5% of the total burden of disease and injury in Australia in 2015, with chronic obstructive pulmonary disease and asthma accounting for 51.4% and 33.8% of this burden, respectively (AIHW 2019).
Influenza and pneumonia are acute respiratory diseases that can be very severe and, in persons at high risk, can lead to death. Influenza and pneumonia cause around 2.5% of all deaths and around 0.9% of hospital separations and are an important cause of hospitalisations in the very young, and of death and hospitalisations among older age groups.
Asthma is a significant public health problem in Australia and it is estimated that Australian prevalence rates are among the highest in the world. Fortunately, recent studies in children show no further increase in prevalence. In Australia in 2015, asthma was estimated to account for 2.5% of the disease burden (AIHW 2019).
Chronic bronchitis and emphysema are the two main conditions comprising chronic obstructive pulmonary disease (COPD). In Australia in 2015, COPD was estimated to account for 3.9% of the disease burden (AIHW 2019).
Tuberculosis (TB) is caused by the bacterial organism Mycobacterium tuberculosis. Despite the increasing burden from respiratory tuberculosis globally, it is not a major public health problem in NSW. In fact the mortality and morbidity from all types of tuberculosis in NSW is one of the lowest in the world.
Lung cancer is usually excluded from analyses of respiratory diseases as it is classified with cancers in the International Classification of Diseases (the coding system used for health data in NSW). It has been included with respiratory diseases here to provide a more appropriate measure of the burden of respiratory disease from a clinical and health services planning perspective.
Cigarette smoking is the main risk factor for both COPD and lung cancer and the current incidence rates of these conditions reflect smoking rates 20 years and more in the past. Lung cancer is one of the leading causes of death in Australia.
Australian Institute of Health and Welfare 2019. Australian Burden of Disease Study: Impact and causes of illness and death in Australia 2015. Australian Burden of Disease Study series no. 19. BOD 22. Canberra: AIHW. Available at: https://www.aihw.gov.au/reports/burden-of-disease/burden-disease-study-illness-death-2015/contents/table-of-contents
Written asthma management plans are recommended as part of the national guidelines for the management of asthma: Australian Asthma Handbook (NACA 2015). They enable people with asthma to recognise a deterioration in their condition and initiate appropriate treatment, thereby reducing the severity of acute episodes.
The Australian Asthma Handbook promotes preventive care activities, proper inhaler technique and adherence and stepped medical management where the use of medicines can be increased or decreased depending on circumstances and the therapy combinations.
Australia is fortunate in having one of the lowest rates of TB in the world. This has been primarily achieved as a result of a continued commitment to provide specialised health services dedicated to the prevention and control of TB in each of the states and territories. The National TB Advisory Committee’s Strategic Plan for the Control of Tuberculosis, 2011-2015 sets out the goals and objectives of TB control in Australia.
Despite Australia’s success in reducing TB, there is no room for complacency. Global connectivity through air travel and migration means that TB will remain a public health concern in Australia until worldwide control of TB is achieved. The NSW TB Program is the provider of specialised services for the prevention and control of TB in NSW and plays a vital role in maintaining Australia’s success in reducing the burden of TB.
Influenza and pneumonia
Influenza and pneumococcal disease are covered by the National Immunisation Programs in NSW.
Influenza has been a notifiable disease by all laboratories under the Public Health Act in NSW since 2001. Surveillance is enhanced in winter months when the NSW Ministry of Health collects and reports weekly on influenza-like illness presentations to Emergency Departments, through the Public Health Rapid, Emergency, Disease and Syndromic Surveillance System (PHREDSS), and laboratory-confirmed diagnoses of influenza virus infections.
Emergency Departments in NSW are prepared for influenza epidemics with peak visit plans and similar measures in winter months.
National Asthma Council Australia. Australian Asthma Handbook. NACA, 2015. Available at: https://www.nationalasthma.org.au/health-professionals/australian-asthma-handbook
Australian Centre for Airways disease Monitoring (ACAM) at http://www.asthmamonitoring.org
National Asthma Council Australia at http://www.nationalasthma.org.au
Australian Bureau of Statistics at http://www.abs.gov.au
Australian Institute of Health and Welfare at http://www.aihw.gov.au
healthdirect at http://www.healthdirect.gov.au