FAQs
Information about our health and health care is recorded throughout our lives as we come in contact with the health system. Much of this information is kept in databases by hospitals, health departments and other organisations that provide health care. Record linkage brings together information that relates to the same individual, family, place or event from different databases. In this way, it is possible to construct chronological sequences of health events for individuals. Combined, these individual “stories” create a larger story about the health of people in NSW and the ACT. This information can be used to plan and improve health services for the population.
Record linkage provides information that gives a more complete picture of the health of the population than was previously possible. The information can be used to study:
- The safety, quality and costs of health care by linking information on different medicines and other treatments with outcomes such as emergency department visits, admissions to hospital, and deaths;
- The relationships among personal, economic and lifestyle factors and health by linking data from research studies and surveys with outcomes such as emergency department visits, admissions to hospital, and deaths; and
- Societal and community influences on health by linking health information with information from other agencies, such as education and community services.
Linking data that already exist is relatively quick and cost-effective compared to performing a research study from the beginning. Record linkage provides data for whole populations that would be prohibitively expensive to collect in any other way. Record linkage also allows research questions to be tested or developed on existing data, allowing better targeting of funding for new research. Record linkage therefore allows more research to be carried out within a given budget and helps ensure that funds available to carry out health and medical research are used most effectively.
Following are some examples of published studies and other projects that have used linked data in NSW:
Studies of risk factors for disease or injury
- NSW Inpatient Statistics Collection data and NSW Midwives Data Collection were linked to determine rates of hypertensive disorders in pregnancy, maternal and infant morbidity and mortality, and level of hospital care for the birth admission. The findings were that women with, and infants exposed to, hypertension were more likely to suffer death or major morbidity than those without hypertension. Infants of mothers with hypertension were more likely to be born preterm and small for gestational age. Just over half the women with major morbidity or mortality delivered in hospitals with a high level of medical care. In contrast, most infants with major morbidity or mortality were delivered in hospitals with neonatal intensive care units.(Roberts CL. Algert CS. Morris JM. Ford JB. Henderson-Smart DJ. Hypertensive disorders in pregnancy; a population-based study. Med J Aust 2005;30:642-648.)
Studies of health services use
- NSW Central Cancer Registry records for women with cancer were linked to records of their surgical treatment in the NSW Inpatient Statistics Collection for the years 1992-1995. Breast conserving treatment was found to have increased in NSW from 39% of breast cancer in 1992 to 45% in 1995. Urban women had fewer mastectomies than rural women.(Kricker A, Haskill J, Armstrong BK. Breast conservation, mastectomy and axillary surgery in New South Wales women in 1992 and 1995. Br J Cancer 2001;85:668-73.)
- Data from the NSW Midwives Data Collection and the NSW Inpatient Statistics Collection is also currently being linked with birth and death registration data from the Registry of Birth, Deaths and Marriages. The aim is to determine to what extent regionalised maternity care is delivering women and their babies in risk-appropriate settings or whether there is room for improvement through increased transfer of at-risk pregnancies to higher levels of care (NSW Centre for Peirnatal Health Services Research, University of Sydney, in progress).
Studies of health services outcomes
- THE NSW Midwives Data Collection, NSW Inpatient Statistics Collection and death registration data from the Registry of Births, Deaths and Marriages, were linked to estimate the risks of maternal and perinatal morbidity and mortality in a second pregnancy, attributable to caesarean section in a first pregnancy. The study did find additional risks, primarily associated with labour.(Taylor LK, Simpson JM, Roberts CL, Olive EC, Henderson-Smart DJ. Risk of complications in a second pregnancy following caesarean section in the first pregnancy: a population-based study. Med J Aust 2005; 183:515-519.)
- Admission data from the Inpatient Statistics Collection was linked with the NSW Emergency Department Data Collection to examine hospital re-admissions and emergency department re-attendances for exacerbations of asthma. Re-attendance is often considered an indication of poorly controlled asthma in the community. The overall rate of re-attendance within 28 days was 7.5%, with the highest rate among those aged 35-64 years, and the lowest rate in those aged 5-14 years. Females had a significant higher re-attendance rate than males (8.1% vs. 6.9%). This study examined a potential indicator of health system performance in relation to asthma.(Correl P, Xuan W, Williamson M, Sundararajan V, Ringland C, Marks G. (in Press). Reattendance for asthma within 28 days using emergency and hospital admission data. Respirology.)
Quality assurance studies of clinical care
- Linkage of the NSW Inpatient Statistics Collection, Registry of Births, Deaths and Marriages death registration data and Australian Bureau of Statistics mortality data can be used to obtain information on death rates and causes of death during and after hospitalisation. A study of death rates following coronary artery bypass surgery is currently underway (NSW Department of Health and Injury Risk Management Research Centre, University of NSW, in progress).
Yes, when the results are published they are available to the public.
Personal information that is provided to the CHeReL is kept highly secure and confidential. Only staff of the CHeReL that are carrying out record linkage work have access to the information. Personal information that is held by the CHeReL is used only in accordance with privacy laws, and in accordance with any conditions placed on the use of personal information by the database owners and human research ethics committees. Also, while the CHeReL holds personal information, such as name and address, it does not store health information, which stays with the original database.
A researcher cannot tell who you are from the project number assigned by the CHeReL.
The owners of databases may only release linked information to researchers that has been approved by a research ethics committee. In most cases this information does not include your personal details. An ethics committee may approve the release of your personal details to a researcher under guidelines issued by the National Health and Medical Research Council. Examples of such circumstances might include:
- if you give your consent; or
- the researcher needs to contact you or your health care provider in order to carry out the project and the ethics committee considers that the likely public benefit of the research outweighs the risk to privacy.
Hospitals, health departments and other organisations that provide health care, record information about people coming into contact with the health system. For example, when a hospital, health facility or pathology laboratory diagnoses or treats someone with cancer they are required by law to notify the NSW Central Cancer Registry. Similarly, information on hospitalisations, emergency department attendances and other health events are submitted to the NSW Department of Health for inclusion in centrally maintained data collections. Collection of such data is required or authorised by a range of health legislation, such as the Public Health Act 1991, the Health Administration Act 1982, and the Private Hospitals and Day Procedure Centres Act 1988. Other authorities are legally entitled to certain information regarding matters of Medicare eligibility, the registering of births and deaths and the circumstances of deaths. There are also databases that include personal information only with patient consent, such as the research database for the 45 and Up Study.
Under the Privacy and Personal Information Protection Act 1998 and the Health Records and Information Privacy Act 2002, a person or organisation must have a lawful reason for collecting information about you.
It is lawful for information to be collected about you with your consent. Examples are: the 45 and Up Study surveys that you complete, or other research projects that you choose to participate in.
It is also lawful for information to be collected about you without your consent where this is authorised by law. For example, certain infectious diseases are required to be reported under the NSW Public Health Act 1991.
The CHeReL only releases data back to data custodians. The CHeReL provides data custodians with a ‘Project Key’ so that they can release linked data to researchers and health planners and policy-makers.
This is the way it works:
Once the approval of a research ethics committee is obtained by the researcher to link two or more databases, the CHeReL uses information such as name, date of birth and address to create a linkage key that points to where records for the same person can be found in the different databases. Information about people’s health does not go to the CHeReL and is not used to create the linkage key, but stays in the original database.
Once the linkage is complete, the CHeReL provides the owners of each database with a list of records to be provided to the researchers and the project key. The owners of each database can then each provide a project database to the researcher, who links the project databases using the project key.
The Human Research Ethics Committee must operate in accordance with National Health and Medical Research Council guidelines.
Records of personal information that are provided to the CHeReL are owned by the organisation(s) that own the source database(s). These organisations have given approval for personal information from their databases to be used by the CHeReL in accordance with relevant ethical approvals.
Should the CHeReL close or the ethical approval(s) that govern the activities of the CHeReL expire, it will be necessary for the CHeReL Management Committee to either establish an alternative legal basis on which to carry out record linkage work of the CHeReL or to cease record linkage activities.
The CHeReL has a policy for record handling if it were to cease operations. The CHeReL Management Committee may seek an alternative management structure and host organisation for the records, subject to approval of the NSW Population and Health Research Ethics Committee and the data custodians. If this is not possible all records will be destroyed, including all current and backup copies.