Data sources

We used data from The Sax Institute’s 45 and Up Study, a longitudinal study of 267,153 Australian residents, described in detail elsewhere⁹. Briefly, a random sample of New South Wales (NSW) residents aged ≥ 45 years from the Medicare Australia enrolment database held by Services Australia (formerly the Department of Human Services) was invited to participate in the study. The database provides near complete coverage of the population. Individuals aged 80 and over, as well as those living in regional and remote areas, were oversampled by a factor of two during recruitment. About 18% of those invited participated, with participants comprising about 11% of the NSW population aged 45 years and over. Participants completed a baseline questionnaire between January 2006 and December 2009 (78% completed the baseline questionnaire in 2008). All participants gave written informed consent for follow-up and linkage of their information to routine health databases.

The 45 and Up Study data include: (1) reimbursements for subsidised outpatient and medical services and some in-hospital procedures covered by the Medicare Benefits Schedule (MBS); (2) inpatient care in public and private hospitals in NSW from the Admitted Patient Data Collection (APDC); (3) emergency department presentation records from the NSW Emergency Department Data Collection (EDDC); (4) cancer diagnoses (excluding non-melanoma skin cancer) from the population-wide NSW Cancer Registry (NSWCR); and (5) death records from the NSW Registry of Births, Deaths and Marriages (RBDM). Individual records were linked to the health database (1) by the Sax Institute using a unique identifier that was provided to Services Australia. NSW Health data for (2) to (5) were provided by the NSW Ministry of Health and Cancer Institute NSW, and individual records were probabilistically linked by the Centre for Health Record Linkage in NSW (CHeReL, http://www.cherel.org.au/) using a best practice approach to linkage while preserving privacy¹⁰. The NSWCR has high standards of data completeness and quality, and the data are accepted by the International Agency for Research on Cancer for publication in Cancer Incidence in Five Continents¹¹.

The study questionnaire is available at https://www.saxinstitute.org.au/our-work/45-up-study/questionnaires/. A participant’s gender (coded as male or female) used in the analysis was obtained at baseline from the Medicare Australia enrolment database or information from the participant that the incorrect baseline questionnaire had been sent. We note that the usual gender terminology refers to “women” or “men”, but have used the terms contained in the Medicare Australia data and the 45 and Up Study data (“male” or “female”).

The conduct of the 45 and Up Study was approved by the University of New South Wales Human Research Ethics Committee. The work in this paper was approved as part of a larger research programme by the NSW Population and Health Services Research Ethics Committee (approval number 2014/08/551), and was performed in accordance with all relevant guidelines and regulations.