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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. 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.
3. Use of selected variables of APDC in this report
3.1 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.
3.2 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 Benefits 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.
3.3 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.
3.4 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.
3.5 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.
3.6 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.
3.7 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.
3.8 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.
4. Differences between figures published by the AIHW and the NSW Ministry of Health and other institutions
4.1 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.
4.2 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.
4.3 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).
4.4 Different projected populations
For the calculation of rates, the NSW Ministry of Health uses population projections based on the population projections prepared by 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.
5. 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: Influenza and pneumonia
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.
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 relevant here.
There were 25,302 hospitalisations due to influenza and pneumonia in 2011-12 (313.0 per 100,000 population), of which 14,013 were patients aged 65 years and older (1,262.9 per 100,000 population in that age group). Males accounted for almost 53% of all influenza and pneumonia hospitalisations.
There were 788 deaths from influenza and pneumonia in 2011 (8.4 deaths per 100,000 population) and almost 92% of these were in persons aged 65 years and over (60.4 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 1993 for all ages and for people aged 65 years and older. A slight increase was subsequently observed in years 2010 and 2011.
Introduction: Respiratory disease
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 7.1% of total burden of disease and injury in Australia in 2003, with chronic obstructive pulmonary disease and asthma accounting for 46% and 34% of this burden, respectively (Begg et al. 2007).
Influenza and pneumonia
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 1.8% 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 2003, asthma was estimated to account for 2.3% of the disease burden (Begg et al. 2007).
Chronic obstructive pulmonary disease
Chronic bronchitis and emphysema are the two main conditions comprising chronic obstructive pulmonary disease (COPD). In Australia in 2003, COPD was estimated to account for 2.9% of the disease burden (Begg et al. 2007).
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 excluded from analyses of respiratory diseases, as it is classified with cancers, and not with respiratory diseases, in the International Classification of Diseases (the coding system used for health data in NSW). However, some indicators analysing respiratory diseases explicitly include lung cancer 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.
Begg S, Vos T, Barker B. The burden of disease and injury in Australia, 2003. Cat. no. PHE 82 edition. Canberra: AIHW, 2007. http://www.aihw.gov.au/publication-detail/?id=6442467990
Interventions: Respiratory diseases
Potentially preventable hospitalisations for chronic conditions
The most common chronic conditions defined as potentially preventable hospitalisations or ambulatory care sensitive hospitalisations are included in the NSW Chronic Disease Management Program (MoH, 2014).
In response to the Garling Report 2008, the NSW Department of Health implemented the NSW Severe Chronic Disease Management Program. The continuation of this program, the Chronic Disease Management Program, is being overseen by the NSW Ministry of Health and NSW Agency for Clinical Innovation. The program provides care coordination and self-management support to help people with chronic disease to better manage their condition and access appropriate services in order to improve health outcomes, prevent complications and reduce the need for hospitalisation.
The Chronic Diseases Management Program targets five major chronic diseases of interest that are recognised as having a major impact on the burden of disease in NSW. Furthermore, these conditions have been demonstrated to have improved outcomes through CDM approaches. The diseases of interest are Chronic Obstructive Pulmonary Disease (mainly emphysema and chronic bronchitis); Coronary Heart Disease (also known as coronary or ischaemic heart disease); Diabetes; Hypertension (high blood pressure); and Congestive Heart Failure.
People who are diagnosed with these diseases and who are experiencing repeated episodes in hospitalisation are offered enrolment to the program. People with these conditions, who are not being admitted to hospital frequently but experience difficulties in managing their conditions, are also eligible for enrolment. The focus is on prevention of deterioration, recognising that people suffering from these diseases often have comorbidities such as depression, arthritis and dementia.
Written asthma management plans are recommended as part of the national guidelines for the management of asthma: Asthma handbook (NACA 2014). They enable people with asthma to recognise a deterioration in their condition and initiate appropriate treatment, thereby reducing the severity of acute episodes.
The 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.
The NSW Tuberculosis Program is successful as the incidence of tuberculosis in NSW remained stable over the last decade despite large-scale migration from high-prevalence countries and the treatment success rates have been high, with the absence of treatment failures and low rates of relapse of cases initially treated in Australia.
The main challenges to the NSW Tuberculosis Program are similar to those that face tuberculosis control globally. They include control of multi-drug resistant and extreme drug-resistant tuberculosis and identification and management of tuberculosis-HIV coinfection (O'Connor et al. 2009).
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 Department of Health collects and reports weekly on influenza-like illness presentations to Emergency Departments , through the Public Health Real-time Emergency Department 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.
NSW Ministry of Health. Chronic Disease Management Program. Sydney: NSW Ministry of Health, 2014. http://www.health.nsw.gov.au/cdm/pages/default.aspx
National Asthma Council Australia. Asthma handbook. NACA, 2014 http://www.nationalasthma.org.au/news-media/d/2014-03-04/new-national-asthma-management-guidelines-released
O'Connor B, Fritsche L, Christensen A, McAnulty J. EpiReview: Tuberculosis in New South Wales, 2003-2007. 2009. Available at www.publish.csiro.au/index.cfm?act=view_file&file_id=NB09001.pdf
For more information: Respiratory diseases
Useful websites include:
Australian Centre for Asthma Monitoring 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