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NSW Admitted Patient Data Collection
The NSW Admitted Patient Data Collection (APDC) or Inpatient Statistics Collection (ISC) is a census of all services for admitted patients provided by public hospitals, public psychiatric hospitals, public multi-purpose services, private hospitals and private day procedure centres in NSW. The APDC is a financial year collection from 1 July through to 30 June of the following year. The information it contains is provided by patients, health service providers, and the hospital's administration. The information reported includes patient demographics, source of referral to the service, service referred to on separation, diagnoses, procedures, and external causes.
For this report, the APDC was accessed via SAPHaRI. THe APDC data is still called the 'ISC' data on SAPHaRI to maintain consistency in naming of SAS datasets.
The APDC includes data on hospital admissions of NSW residents which occurred in hospitals interstate. The only exception to this is that data from interstate hospitals for the year 2006-07 were not yet available when the data was analysed. This may affect analyses and has a greater effect on rates for areas closer to an interstate boundary. Analyses by Health Area and analyses involving uncommon diagnoses or procedures are particularly affected. Therefore, ab estimate was made of interstate admissions for 2006-07. The estimate was based on admissions for the preceding three years (2003-04 to 2005-2006). The first step was to determine the proportion of total admissions for NSW residents in the preceding three years which were at interstate hospitals. That proportion was used to multiply the number of admissions at hospitals in NSW in 2006-07, to obtain the estimate of the number of admissions expected to have occurred at interstate hospitals. The estimates were calculated for each age-sex stratum. Where hospitalisations were further categorised, for example by diagnosis, geographical place of residence or country of birth, the imputation procedure was carried out separately for each category, thus accounting for the uneven distribution of interstate hospital admissions.
From 1 July 1998, inpatient data on SAPHaRI (formerly HOIST) have been for episodes of care in hospital. Episodes of care end with the discharge, transfer, or death of a patient. A new episode of care may also start when the service category for an admitted patient is altered, as a result of a change in the on-going clinical care requirements for that patient during the one episode of accommodation in a single facility. APDC data on SAPHaRI up to 30 June 1998 were for periods of stay in hospital. A period of stay in hospital ends with the discharge, transfer, or death of a patient, and may consist of multiple episodes of care. The change from 'period of stay' to 'episode of care' causes a small increase in the apparent number of admissions.
The reason for a hospital admission is coded at the time of separation (discharge, transfer or death). Since 1 July 1998, coding has been according to the 10th revision of the International Classification of Diseases, Australian Modification ICD-10-AM. Updated ICD-10 coding manuals have been published by the National Centre for Classification in Health every two years since 1998. Prior to this, coding was according to the 9th revision of the International Classification of Diseases, Clinical Modification (ICD-9-CM), using the Australian version (National Coding Centre, 1996) from July 1995 and the US version prior to that.
Since 1 July 1998, procedures carried out during a patient's stay have been coded according to the MBS-Extended Procedure Classification, published as Volume 3 and Volume 4 of the 10th revision of the International Classification of Diseases, Australian Modification (ICD-10-AM). Updated ICD-10 coding manuals have been published by the National Centre for Classification in Health every two years since 1998. Prior to this, procedures were coded according to the 9th revision of the International Classification of Diseases, Clinical Modification (ICD-9-CM), using the Australian version (National Coding Centre, 1996) from July 1995 and the US version prior to that.
The numbers of diagnosis and procedure codes that may be recorded, at the time of separation, have varied over time, and are currently as follows:
· principal diagnosis (the principal reason for admission);
· up to 54 other diagnoses;
· up to 50 procedures and procedure blocks;
· up to eight external cause codes for injury and poisoning.
· up to three codes for place of occurrence injury or poisoning.
· up to three codes for activity at time of injury or poisoning.
Mapping tables between ICD-9-CM and ICD-10-AM disease codes, produced by the National Centre for Classification in Health, were used extensively to obtain the most appropriate match for individual codes between the two classification systems. The ICD-10-AM and ICD-9-CM codes used for each indicator are included in the disease and procedure codes section of the appendix.
1. Hospital statistics in NSW
All NSW public hospitals, public psychiatric hospitals, public multi-purpose services, private hospitals and private day procedure centres in NSW report data on patients admitted for care to the NSW Ministry of Health. Patient separations from developmental disability institutions and private nursing homes are not included. These reported data, from about 400 different facilities in NSW, are called the NSW Admitted Patient Data Collection (APDC).
The collection also includes data relating to NSW residents hospitalised interstate (see below in Imputation for more details) and in Commonwealth Department of Veterans’ Affairs facilities.
Each reporting facility has its own Patient Administration System (PAS), there are five types of these in NSW: HNMA Millenium (administered by Cerner), WinPAS, iPM (I-Soft), HOSPAS (legacy system being phased out and replaced with other systems) and ISCOS, which is the Inpatient Statistics Collection On-line System used by private hospitals. Data from the PAS systems are loaded into the Health Information Exchange (HIE) in a standard format. The HIE is the data warehouse for the whole NSW health system maintained by the NSW Ministry of Health which is accessed by authorised staff across the health system and in the NSW Ministry of Health. Data from the HIE are extracted and loaded onto the Secure Analytics for Population Health Research and Intelligence (SAPHaRI) warehouse, administered by the Centre for Epidemiology and Evidence and used for this report.
2. Hospitalisation rate definition
A hospitalisation rate is an estimate of the proportion of a population that was hospitalised during a specified period. It is expressed in this report as the number of hospitalisations per 100,000 population per year (person-years). Age and sex standardisation (also called ‘adjustment’) adjusts for differences in the age and sex structure of populations and is performed to make rates comparable between different sub-populations in the same geographic area; in the same population over time; or between different geographic areas at the same time (for example between different States and Territories or different Local Health Districts). This assists in interpreting variations in patterns of hospitalisations between groups and over time after controlling for factors such as age, which are commonly associated with increased disease rates.
Hospitalisation rates in this report are standardised to the 2001 Australian standard population.
3. The Admitted Patient Data Collection and this report
The Admitted Patient Data Collection (APDC) is a census of all inpatients treated in NSW and includes data on NSW residents treated in other states. The APDC was, up to 2002, known as the Inpatient Statistics Collection. The APDC contains approximately 70 variables and is based on a financial year cycle beginning on 1 July and ending on 30 June of the following year.
The APDC data used in this report are the SAPHaRI (Secure Analytics for Population Health Research and Intelligence) data warehouse, maintained by the Centre for Epidemiology and Evidence. The APDC data is extracted from the Health Information Exchange (HIE) and undergoes a quality assurance and standardisation process before being loaded onto SAPHaRI in a SAS dataset format.
Further information on the APDC and SAPHaRI is available in this report in Methods tab under The Admitted Patient Data Collection title.
4. Use of selected variables of APDC in this report
4.1 Principal diagnosis and additional diagnoses coded to the ICD-9-CM and ICD-10-AM
Each hospital episode in the APDC is described by a principal diagnosis and additional diagnoses, which are coded using the International Statistical Classification of Diseases and Related Health Problems: ICD-9-CM (up to June 1998) and ICD-10-AM (from July 1998 onwards). Please refer to a separate Methods section on Principal and additional diagnoses for a detailed discussion (this section accompanies selected indicators that include principal and additional diagnoses, for example diabetes hospitalisations).
In this report the count of hospitalisations for a condition is based mainly on principal diagnosis. If an indicator contains analysis of data in additional diagnosis fields as well ('comorbidities'), this is clearly stated in the title of an indicator and in the Notes. The Notes specify how many additional diagnosis fields were included in the analysis. Another exception is the topic of injury and poisoning where the count is based on ‘external cause of injury’. See Methods for injury and poisoning indicators.
The number of additional diagnoses that are included in the hospital records is restricted to conditions which fulfil several requirements, including direct relevance to the treatment and management of the principal diagnosis. This ensures that only the most resource intensive or clinically relevant conditions are listed for that hospitalisation rather than all comorbidities that a patient may have. Data on additional hospital diagnoses cannot therefore be used to estimate the prevalence of a condition in the community.
4.2 Procedures coded to Australian Classification of Health Interventions
Procedures performed in Australian hospitals are coded in medical records using the Australian Classification of Health Interventions (ACHI) published by the National Centre for Classification in Health. This classification is based on the Commonwealth Medicare Benefit Schedule and relates to anatomy rather than surgical specialty.
Up to 30 June 1998, the ICD-9-CM Procedure Classification was used in Australia. This was based on WHO Surgical procedures (edition 5) and was not revised and carried beyond 1998 by the WHO due to the rapid advancements in the field of procedures (National Coding Centre 1996).
On 1 July 1998, both the ACHI and the ICD-10-AM were introduced in NSW. They are revised every two years. The ICD-10 is the WHO classification but the AM suffix stands for Australian Modification, which adds detail necessary to describe practice in Australian hospitals. The ICD-10-AM is fully compatible with ICD-10 (NCCH 2006).
Up to the fourth edition of ICD-10-AM in 2004, the ACHI was published as a part of the ICD manuals (volume 3 and 4), from the fifth edition in 2006 the titles of the ACHI publication emphasise that this is a classification independent from the ICD.
Both ICD-9-CM Procedure Classification (up to and including 1997-98) and Australian Classification of Health Interventions (from 1998-99 onwards) are used in this report.
4.3 Episode of care based count of hospitalisations
The count of hospitalisations in this report is based on an episode of care from 1 July 1998 (ISC EOC datasets on SAPHaRI). A patient can have several episodes of care during one hospital stay, that is, between the formal admission and the formal discharge (separation) from hospital.
The episode of care is defined by a service category. An episode of care starts when the hospital stay starts or when the service category changes. There are ten service categories: acute care, rehabilitation care, palliative care, maintenance care, newborn care, other care, geriatric evaluation and management, psychogeriatric care, organ procurement-posthumous and hospital boarder.
A new episode of care starts also when a patient is on leave from hospital: more than 4 days away in any hospital and more than 10 days away in psychiatric hospitals.
4.4 Overnight and day-only hospital stays are included
Both overnight and day-only hospitalisations are included in this report, unlike in the national reporting on hospital statistics (AIHW Health services series no. 40. Cat. no. HSE 107 2011), where day-only hospitalisations are not included.
The only exceptions are the count and rate of hospitalisation for falls in elderly (persons aged 65 years and over) in NSW, where day-only hospitalisations are excluded from the key indicator reports in NSW. NSW performance reporting of hospitalisations for falls in elderly in NSW includes overnight (and longer) hospitalisations. However, in this report, an analysis of day-only hospitalisations and the total of overnight and day-only hospitalisations are also included in the relevant indicator for comparison and completeness.
4.5 Full census of hospitalisations from 1993-94 and sampling factor prior to 1993-94
In 1993-94 the APDC (then known as the Inpatient Statistics Collection) was a fully enumerated survey (that is a census) for the first time. Datasets containing financial years earlier than 1993-94 are based on estimates from a sample of all inpatient data in some hospitals, partiularly in rural areas, and their use in analysis requires the inclusion of a sampling factor weighting variable.
4.6 Separation date determines the year of hospitalisation
The main record file of the hospital stay for a patient is created or completed on separation from hospital when all relevant documentation is made available to hospital medical record departments. Consequently, the main reason for hospitalisation (principal diagnosis) completed at separation, may be different from the admitting diagnosis. The hospitalisation is counted in the year when the separation took place even if the hospitalisation period occurred predominantly in the previous financial year. For example a patient discharged on 1 July after a 4 week hospital stay would be counted as hospitalised in the new financial year.
4.7 Imputation of interstate hospitalisations in the last year of data
At the time when the NSW Ministry of Health completes the Admitted Patient Data Collection for the previous financial year, data on hospitalisations of NSW residents in other states are usually not available and so interstate hospitalisations for the latest year is always ‘imputed’ from the previous three years in this report. This imputation process estimates the number of hospitalisations occurring in other states for each diagnosis in previous years and adds these numbers to the latest year of data. When the actual data become available, the number and rates for the affected year are re-calculated.
4.8 Summary of major changes in the hospital data on SAPHaRI
1988-89: Hospital data included from the Inpatients Statistics Collection (ISC) counted on the basis of a "period of stay" in hospital (ie multiple episodes of care). ICD-9-CM used and sampling from some hospitals (requiring a sampling factor for weighting numbers in these hospitals).
1993-94: Admitted Patient Data Collection (APDC) is a fully enumerated census of hospitalisations.
1998-99 onwards: APDC starts to be counted as episodes of care. ICD-10-AM replaces ICD-9-CM; and Australian Classification of Health Interventions replaces ICD-9-CM Procedure Classification.
Imputation for interstate hospitalisations: The latest year of data (number and rates) are ‘imputed’ for missing interstate hospitalisations for NSW residents. The actual number of interstate hospitalisations is included when available.
5. Differences between figures published by the AIHW and the NSW Ministry of Health and other institutions
5.1 Differences in publication schedules
The APDC dataset is continuously updated because it is not uncommon to receive additional records or additional information on records already supplied well after the close of a financial year. Consequently data on hospitalisations in NSW from different sources, such as this report and the AIHW report, will always differ slightly due to different publication schedules.
5.2 Imputation of interstate hospitalisations in the latest year of data
In this report imputation methods are used to estimate the number of hospitalisations of NSW residents occurring elsewhere in Australia in the latest year due to a lag in receiving this information (see above). Over some periods of time two last years of data need to be imputed. Refer to Notes in the indicator for confirmation how many years are imputed at the time. Estimates may vary slightly from the estimates in other releases of this report or other reports because of the imputation. The actual number of interstate hospitalisations is included when relevant.
5.3 Definition of hospitalisation
Both overnight and day-only hospitalisations are included in this report, unlike in the national reporting on hospital statistics, where only overnight hospitalisations are included (AIHW Health services series no. 40. Cat. no. HSE 107 2011).
5.4 Different projected populations
For the calculation of rates, the NSW Ministry of Health uses population projections based on the NSW Health Population Projection Series, prepared by the Statewide Services Development Branch of the NSW Ministry of Health in collaboration with the NSW Department of Planning. Refer to Methods in Population-Demography topic for further information on projected populations and other issues mentioned here. The rates in this report are expressed as a number per 100,000 population.
Rates published by the Australian Institute of Health and Welfare may be expressed differently (per 1,000 or 10,000 population) and use different projected population estimates for NSW. The population estimates, which are not projected, are likely to be the same, as these are based on the estimated residential populations published by the ABS.
6. Other datasets holding data on activity in hospitals
The APDC datasets contain information on inpatient hospital activity. Emergency department data and Outpatient activity data are also available to report on hospital activity.
Australian Institute of Health and Welfare. Australian hospital statistics 2009–10. Health services series no. 40. Cat. no. HSE 107. Canberra: AIHW, 2011. Available at http://www.aihw.gov.au/publication-detail/?id=10737418863 (Cited on April 2011).
National Centre for Classification in Health. The International statistical classification of diseases and related health problems, 10th Revision, Australian Modification (ICD-10-AM). Australian Coding Standards. Sydney: NCCH, 2006.
National Coding Centre. The Australian version of the International Classification of Diseases, 9th revision, clinical modification (ICD-9-CM). Sydney: University of Sydney, 1996.
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Codes: Influenza and pneumonia
The International Statistical Classification of Diseases and Related Health Problems
National Centre for Classification in Health, Australia; CM - Clinical Modification; AM - Australian Modification
In 2009, the WHO recommended that ICD-10-AM J09 code be used to cover influenza A/H1N1 (initially called ‘swine flu’) responsible for the pandemic 2009 and the code has been added to the set of codes above.
Key points: Communicable diseases
Among the most frequently reported notifiable conditions in 2012 were:
Note: The rates quoted above are age adjusted rates.
Conditions in 2012 with the most marked declines compared to previous years included:
Conditions in 2012 with the most marked increases compared to previous years included:
Introduction: Communicable diseases
Definition and burden of disease in Australia
Bacteria, viruses or parasites infect humans as a result of contact with other infected humans, animals or the environment. Certain communicable diseases are of high priority for health departments around the world, because they are highly infectious, can result in serious illness or death, or can be prevented by immunisation or other actions.
Only in the last 200 years or so has the understanding of the germ theory and the importance of some of the most important yet basic public health measures, such as availability of running water and hand-washing, been recognised. The development of immunisation, first against smallpox, and later for a growing number of other diseases including diphtheria, pertussis, tetanus, polio, and measles, led to massive declines in morbidity and mortality associated with these conditions.
The potential for serious outbreaks and emerging or re-emerging infectious diseases continues to present a challenge in public health and requires planning and constant vigilance. Each year, over 200,000 individual notifications of communicable diseases are reported in Australia. These trigger a considerable amount of public health action so that cases are treated, the spread of disease is limited, the source of infection is removed or minimised and outbreaks are controlled or prevented.
Public Health Act 2010
Under the Public Health Act 2010 (and previously under the Public Health Act 1991), laboratories, hospitals, medical practitioners, schools and child care centres must notify NSW Health of diagnoses of certain diseases. For some diseases a notification triggers a public health response by the public health unit, such as immunisation or prophylactic treatment of contacts. Notifications also provide valuable information that is used for planning and evaluation of prevention programs.
The number of notifications received for any particular condition is almost always an underestimate of the number of cases that actually occur. For a condition to be notified a patient must seek medical help, be diagnosed with the condition, in some cases must have the appropriate laboratory tests done and then the diagnosis must be reported to NSW Health. Nonetheless, communicable disease notifications provide valuable information on disease patterns in NSW.
Public Health Act 1991 and Public Health 2010. Available at http://www.legislation.nsw.gov.au/maintop/view/inforce/act 127 2010 cd 0 N
Interventions: Communicable diseases
Response to notifications under Public Health Act 2010
For some diseases a notification triggers a public health response by the public health unit, such as immunisation or prophylactic treatment of contacts. Notifications also provide valuable information that is used for planning and evaluation of prevention programs.
In 2012 NSW Health:
• maintained high immunisation coverage rates for children at 1, 2 and 5 years of age. While coverage rates in Aboriginal and non-Aboriginal children are comparable at 2 and 5 years of age, coverage in Aboriginal children is markedly less at 1 year of age. Aboriginal children are more likely to be vaccinated late at any age
• funded a pilot program to employ Aboriginal Health Workers to work collaboratively with existing services to promote timely vaccination of Aboriginal children through targeted interventions
• developed an immunisation awareness campaign to inform the community and providers about the importance of ensuring that children are fully vaccinated on time• successfully implemented the transition from Prevenar 7 to Prevenar 13 vaccine for children at 2, 4 and 6 months of age, and a supplementary program for children who had commenced Prevenar 7 vaccination to provide greater protection against pneumococcal disease
• introduced a more focused pertussis control strategy by offering new mothers free pertussis vaccine in the maternity unit after the birth of their child or via their general practitioner within 2 weeks post-birth
• increased immunisation coverage rates for adolescents in the NSW School-Based Vaccination Program for all vaccines offered to students in Years 7 and 10
• facilitated the provision of free seasonal influenza vaccine to people at high risk of severe influenza complications. The NSW Health Population Health Survey estimated that 31% of all respondents interviewed during August and September 2012 had received a seasonal influenza vaccine in the previous 12 months, a slight decrease in vaccine uptake compared with the estimate for the same period in the previous year (33%). In respondents aged 65 years and over, that is in one the identified high-risk groups, the estimated vaccination rate was 72%, which was similar to previous years.
In 2012 Health Protection NSW:
• initiated a range of control measures to contain the measles outbreak, including sending letters to health care providers, issuing media alerts, developing measles alert posters and other materials for health care facilities and local GPs, and holding free local vaccination clinics in areas with high rates of measles infections
• continued an influenza prevention campaign that focused on three key respiratory disease prevention messages: Cover your face when you cough or sneeze; Wash your hands; and Stay at home if you're sick so you don't infect others. The campaign included distribution of The Spread of Flu is Up to You campaign posters, vaccination and pregnancy brochures, and infection control signage to health care facilities, aged care facilities and a range of other sectors
• with local Public Health Units and an expert sub-committee of the NSW Tuberculosis Advisory Committee, continued to develop and implement strategies to eliminate transmission of tuberculosis in Aboriginal communities in NSW. This work involves better understanding of barriers to early presentation to health services and non-compliance with treatment for latent tuberculosis infection, and investigation of strategies to raise awareness and increase early diagnosis of tuberculosis. The Northern NSW and Mid North Coast Local Health Districts have employed two Aboriginal Community Engagement Consultants to work directly with Aboriginal communities in the Northern and Mid North Coast regions in awareness-raising and prevention activities
• continued the NSW Arbovirus Surveillance Program, which included testing for both alphaviruses (Barmah Forest, Ross River and Sindbis virus) and flaviruses (Alfuy, Edge Hill, Kokobera and Stratford) in mosquitoes trapped at 20 coastal, inland and metropolitan locations, and testing of chickens for antibody seroconversion to Murray Valley encephalitis virus and Kunjin virus at 10 sites in inland NSW from November to April. During the 2011–2012 season inland areas had seen considerable arboviral activity with 67 isolates from mosquitoes and 15 seroconversions for Murray Valley encephalitis virus in chickens. Inland areas have also seen extremely high numbers of mosquitoes due to excessive precipitation and flooding. Coastal and Sydney metropolitan areas had low vector abundance and minimal arboviral activity
• issued statewide media releases in January, March and December, warning about the increased risk of mosquitoborne infections and how to prevent them. In addition, advice on mosquito control in flood-affected areas was provided to councils and the general public in March. These were supplemented by the information on the Ministry of Health website, development of guiding principles for environmental health officers, distribution of Fight the Bite posters and brochures, radio advertising and a range of local media messaging by public health officials.
Prevention Activities for Enteric Diseases
Enteric diseases are viral and bacterial infections of the gastointestinal tract. Many are caused by pathogens found in food and water.
NSW Health works with OzFoodNet nationally and the NSW Food Authority (NSW FA) locally to investigate and control food borne outbreaks and food contamination incidents, and to make prevention recommendations. Further information about enteric diseases can be found in OzFoodNet reports at http://www.health.nsw.gov.au/Infectious/foodborne/Pages/ozfoodnet-rpt.aspx
Australian Institute of Health and Welfare. Australia’s health 2010. Australia’s health series no. 12. Cat. no. AUS 122. Canberra: AIHW, 2010. Available at http://www.aihw.gov.au/publication-detail/?id=6442468376
National Health and Medical Research Council and Natural Resource Management Ministerial Council. Australian Drinking Water Guidelines 6, 2011.
Natural Resource Management Ministerial Council; Environment Protection and Heritage Council. Australian Health Ministers’ Conference. Australian Guidelines for Water Recycling: Managing Health and Environmental Risks (Phase 1). 2006. Available from: http://www.ephc.gov.au/sites/default/files/ WQ_AGWR_GL__Managing_Health_Environmental_Risks_ Phase1_Final_200611.pdf
NSW Department of Health. Drinking Water Monitoring Program. December 2005.
For more information: Communicable diseases
Useful websites include:
NSW Department of Health Infectious Diseases web page at http://www.health.nsw.gov.au/publichealth/infectious/index.asp
Australian Government. Department of Health and Ageing. National Notifiable Diseases Surveillance System, available at http://www.health.gov.au/internet/main/publishing.nsf/content/cda-surveil-nndss-nndssintro.htm
and Communicable Diseases Intelligence at http://www.health.gov.au/internet/main/publishing.nsf/content/cda-pubs-cdi-cdiintro.htm
Australian Bureau of Statistics at http://www.abs.gov.au
Australian Institute of Health and Welfare at http://www.aihw.gov.au
HealthInsite at http://www.healthinsite.gov.au
Public Health Act 1991 and Public Health Act 2010. Available at http://www.legislation.nsw.gov.au/maintop/view/inforce/act 127 2010 cd 0 N
National Immunisation Program Schedule at http://www.health.gov.au/internet/immunise/publishing.nsf/content/nips2
NSW Ministry of Health Immunisation web page at http://www.health.nsw.gov.au/publichealth/immunisation/index.asp