The 2003 Australian Breast Health Survey: survey design and preliminary results

Breast cancer is the most common registerable cancer and is the leading cause of cancer-related death in Australian women [1]. In 2002, more than 12,000 were diagnosed with the disease and almost 2,600 died from it. By 2011, it is predicted that the number of new cases will exceed 14,800 [1].

In 1996, the National Breast Cancer Centre (NBCC) conducted the first national Breast Health Survey (BHS) to gain insight into the knowledge, attitudes and behaviour of a nationally representative sample of Australian women on issues relevant to breast cancer [2, 3]. Key areas of investigation included respondents' understanding of the incidence of breast cancer, risk factors, early diagnosis, treatment and the availability and accessibility of information and services.

The results of the 1996 BHS were extremely useful in establishing baseline rates against which to assess the effectiveness of community information programs conducted by the NBCC and others. In addition, the findings suggested the areas upon which such programs might focus. For example, although it was clear that women were aware of the importance of breast cancer as a significant disease in the community, there was a need to emphasise that a diagnosis of breast cancer did not equate to certain and immediate death and that many women with breast cancer could be treated effectively [3].

In 2003, the NBCC undertook a second survey of a nationally representative sample of Australian women. The 2003 BHS retained a number of methods and questions from the 1996 BHS, as well as including questions on previously unexplored areas. In the following paper, we describe major aspects of the approach and design of the 2003 BHS and present results focusing on respondents' knowledge about mammographic screening.

The NBCC Breast Health Surveys were designed to measure the knowledge, attitudes and behaviour of a nationally-representative sample of women aged between 30 and 69 years. The findings reported in this publication focused on aspects of screening mammography. The results showed areas of improvement while highlighting issues requiring additional development. This, at its core, was the main purpose of the BHS – as an evaluative tool in the continuous improvement of public awareness and health programs in relation to breast health.

About three out of every five age-eligible women interviewed had a mammogram in the past, similar in magnitude to those rates reported elsewhere in the world [12‐14], but lower than the target participation set by the BreastScreen Australia Program of 70% [15]. Overall awareness of BSA approached 90%, suggesting that promotion of the national program has been successful. This confirms a general trend toward more widespread recognition of the availability of mammographic screening in Australia [16]. The present results also point to significant differences in awareness by age and area of residence suggesting that future programs, including expanded health promotion campaigns and social marketing activities, should target particular groups.

Equally important were the findings that more than 80% of women knew that the service was free of charge and were "very confident" in arranging a screening mammogram, confirming that community understanding of specific details accompanies its wide promotion and dissemination.

The 28% increase between the 1996 and 2003 BHS in women reporting that their general practitioner had recommended mammographic screening may be due to the success of campaigns directed at general practitioners to encourage screening and early detection in the course of routine care or opportunistically when in consultation with women for other reasons. The coordination of care performed by general practitioners (akin to the North American model of "gatekeeping" primary care physicians [17]) has been shown to increase the uptake of mammographic screening [18‐20]. However, the gains in general practitioner participation notwithstanding, more research needs to be undertaken in order to more comprehensively increase the participation rate from the nationwide average (57.1% of the target population in 2001–02 [21]).

The 2003 BHS shows that there is still much confusion about screening as opposed to diagnostic mammography. About 95% of women reported that attendance at BSA was available to women regardless of symptoms. In fact, as for all population screening programs, the BSA program is for asymptomatic women. It is important that this confusion between the management of asymptomatic and symptomatic women be clarified to avoid delays in diagnosing a potentially malignant condition. In addition, previous research has indicated that women who do not appreciate the distinction between diagnostic and screening tests may be more likely to seek compensation for missed diagnoses [22]. Women experiencing symptoms are best managed by undergoing individual assessment and investigations for the cause of the symptoms. The National Breast Cancer Centre recommends the use of a "triple test" of a clinical examination, imaging and/or non-excisional tissue biopsy [23].

Our findings were derived from self-reports. Such data will be affected by the participant's ability to recall events in the past. Moreover, it is well known that survey participants tend to under-report socially unacceptable or unhealthy behaviour and over-report socially desirable ones [24]. We attempted to reduce this effect by assuring confidentiality [25], using indirect question construction techniques [26], and the use of the same questions from the 1996 BHS. This use of the same questions also allowed for comparability across time periods and a retention of consistency of investigation.

While only 35% of eligible numbers resulted in an interview, this figure is not unusual for this type of research. Much has been written about the declining response rates for surveys conducted over the telephone [27‐29] For instance, Curtin and colleagues reported that response rates have declined over a 24-year period from 72% in 1979 to 48% in 2003 [30]. This has been due to a number of factors including increased refusals (such as those due to time constraints or the number of survey requests) and declining contact rates (for instance, the current phenomenon of call screening technology through caller ID and answering machines).

Our results are likely to be biased estimates of true population values due to the exclusion of potential respondents who did not have listed telephones or who did not speak English. In addition, respondents who agreed to participate may have more knowledge or experience than those who refused. Moreover, the sampling process selected one woman aged between 30 and 69 from each household and those women living in households with more than one woman in the required age group had a lower chance of selection. This has not been accounted for in the sample weighting. However, an analysis of the 1% sample file of the 2001 Australian Census of Population and Housing showed that only 3.7% of households have more than one woman aged between 30 and 69, so the impact of this feature is likely to be small. Overall, the net effect of such issues is difficult to predict. However, to the extent that these potential considerations show temporal variability, the possibility that the results across both surveys may validly point to true differences in knowledge, attitudes and behaviour cannot be discounted.

The NBCC Breast Health Surveys provide a valuable picture of the knowledge of Australian women about a range of issues. The present analysis shows significant gains in knowledge and behaviours relating to mammographic screening, while identifying additional areas for targeted improvement, as in the need to better communicate with women about screening and diagnostic services. Further analysis of additional core topic areas (eg., incidence, mortality, risk and treatment) will provide equally noteworthy insight.