Screening Coverage Indicators

Vaccination against HPV will take decades to reduce overall cervical cancer incidence, due to the time taken for vaccinated cohorts to reach the age at which they would have developed cancer and also to make up a large enough proportion of the population to affect overall incidence rates. Cervical screening therefore is important to expedite elimination of cervical cancer (2,32,33). The WHO strategy to accelerate the elimination of cervical cancer sets a target of screening women at least twice, at around age 35 and 45 years. Based on data from Victoria, around 40% of the women diagnosed with cervical cancer had never been screened (34-36), emphasising the importance of this indicator, even though more frequent screening is recommended in the NCSP.

Primary HPV screening has been recommended in Australia since 1st December 2017, not yet long enough for any women to have had a primary HPV test by age 35 and another by age 45. The second part of this indicator therefore reports on the proportion of women aged 45-49 who have been screened at least twice, including at least one primary HPV test and at least one cytology test prior to 1st December 2017 at least two years apart, as an interim measure.

By the end of 2021, 73.8% of women aged 35-39 years had been screened at least once with an HPV test. Being screened twice with a high-performance test by age 45 cannot be properly assessed until primary HPV screening has been available for longer in Australia, but 69.5% of women aged 45-49 years had been screened at least twice, including at least once with an HPV test (Figure 7.1). In most areas, at least 70% of women aged 35-39 had been screened at least once with an HPV test, apart from women living in areas that were inner regional (69.8%), very remote (64.7%) or in the middle socioeconomic quintile (68.8%). The proportion of women aged 45-49 who had been screened at least once with an HPV test plus at least once previously with a cytology test reached at least 70% by the end of 2021 in several areas, including SA and ACT; in major cities; and among women living in SES quintiles 2 and 5 (least disadvantaged).  The proportion of those aged 45-49 years with two such tests exceeded 65% in most areas, and exceeded 60% in all except very remote areas (58.8%).

As expected, the proportion of eligible women aged 35-39 years who have had at least one HPV test has increased with each year since the HPV screening program began, from 31.0% at the end of 2018, to 73.8% by the end of 2021 (Figure 7.2). This increase has been seen in every population group for which data were available to report on, however the difference between the groups with the lowest and highest uptake has increased somewhat over time. The proportion of eligible women aged 35-39 years with at least one HPV test has consistently been lowest for women living in very remote areas, and highest for women living in the least disadvantaged areas. There was more variation by remoteness area (range: 64.7% to 74.3% in 2021) and area-level socioeconomic status (range: 68.8% to 78.8% in 2021) than there was by state/ territory (range: 72.1% to 76.0%).

The same patterns were seen for the proportion of eligible women aged 45-49 years with at least one HPV test plus at least one earlier screening test (noting this is an interim measure and not the same as the WHO target, which requires two appropriately spaced HPV tests), including the groups where this proportion was consistently lowest and highest. This measure increased from 31.0% at the end of 2018 to 69.5% at the end of 2021, and very substantial increases were seen in all areas (ranging from an increase of 33.4% in Tasmania to 44.5% across major cities). (Figure 7.3).

Source: Analysis of NCSR data (NCSR RDE 3.4.1. 08/01/2022 for 2021; NCSR RDE 3.4.1 07/08/2021 for the years 2018, 2019, and 2020); data prepared by the Screening Analysis and Monitoring Unit of the Australian Institute of Health and Welfare.

Women who are eligible for screening comprise the estimated resident female population, minus an estimate of the number of women who have had a hysterectomy and the number of women enrolled in the Compass trial, consistent with routine AIHW reports (1,3,37-39). ABS population estimates from (38,39). Hysterectomy prevalence estimates are from an AIHW analysis of National Hospital Morbidity Database (3). Aggregate numbers of Compass participants were extract from the Compass Trial Register. Data to calculate the screen-eligible population by single year of age were not available.

This WHO indicator was designed to be a minimum target for low and lower-middle income countries and does not necessarily reflect the preferred approach for higher income countries. Being screened at least once substantially reduces a woman’s risk of cervical cancer (40,41). The WHO target for this measure was set for 2030; modelling used to inform the WHO targets assumed that screening uptake would scale up further after this time (to 90%) (12,32). As Australia has a well-established screening program, it may reach the 2030 target and scale screening up earlier than other countries. 

Data on Indigenous status are not yet sufficiently complete on the NCSR to allow reporting by Indigenous status. Given cervical cancer incidence rates are much higher among Indigenous women, and cervical screening is critical to reduce cervical cancer incidence in the nearer term, understanding and reporting screening coverage in Indigenous women is critical to achieving timely elimination among Indigenous women. Earlier studies of the cytology-based screening program, based on analyses of ad hoc linked data for Qld, NSW, and the NT (19,42,43), found that Indigenous women were less likely to have been screened in the previously recommended interval of two years, and over a longer interval of five years.

The proportion of women aged 35-39 years who have had at least one HPV test is expected to increase over time, as data included here only capture the first four years since primary HPV screening was recommended (although all screen-eligible women would have been due to attend for their first HPV test by 31st December 2019). The impact of providing self-collection as a choice for all people eligible for screening (which only became available in July 2022) is not reflected in the timeframe of this report. It is anticipated that the national scale-up of this choice could help to increase equity in screening participation and may be particularly helpful in reaching women living in very remote areas, who consistently had the lowest uptake on this measure.

The hysterectomy prevalence estimates that are used to derive the population eligible for cervical screening are from an AIHW analysis of National Hospital Morbidity Database, and so consistent with other reports, however these estimates are not broken down by state/territory, remoteness area, or area-level SES. Potentially the prevalence of hysterectomy does vary across these strata, so using national age-specific estimates may under- or over-estimate the population who are eligible for screening in some cases.

Cervical screening is important to expedite elimination of cervical cancer, as HPV vaccination requires several decades to have its full effects across the population. As Australia has a well-established screening program with screening recommended aligned with the broader WHO screening recommendations (44) but more frequently than in the WHO elimination strategy (2), the proportion of women screened according to Australian recommendations is additionally reported. Since 1st December 2017, Australia has recommended 5-yearly primary HPV screening starting at age 25 and an exit test to occur between the ages of 70-74 years; prior to this, 2-yearly cytology was recommended for women aged 20-69 years. Women were due to attend for their first HPV test two years after their last negative routine cytology test, or when they turned 25, whichever was later.

Nationally, 71.9% of eligible women were up to date with recommended screening at the end of 2021. Data were not available to report on this measure for Indigenous women. There was some variation across different areas of Australia (Figure 8.1). The proportion who were up to date decreased with increasing remoteness of residence, from 73.0% in major cities to 62.7% in very remote areas. There was less variation by state and territory, where the proportion who were up to date ranged from 68.8% (Tas) to 73.9% (ACT).

As expected, coverage has increased in all groups in each year after the first two years since the transition to HPV screening, due to the longer screening interval. The absolute increase is broadly similar across most groups, and around 20 percentage points. Exceptions are those aged 25-29 years, where the proportion of eligible women up to date with screening increased from 40.8% at the end of 2018 to 53.3% by the end of 2021, an increase of only 12.5%; and those aged 70-74 years, where it increased from 26.5% to 55.5%, an increase of 29.0% (Figure 8.2). The proportion of eligible women who were up to date with recommended screening at the end of each year (over 2018 to 2021) was consistently highest for women living in the least disadvantaged areas and those aged 50-54 years, and lowest for women living in very remote areas (and those aged 70-74 years until 2020; in 2021, this switched to being lowest in those aged 25-29 years).

Source: Analysis of NCSR data (NCSR RDE 3.4.1. 08/01/2022 for 2021; NCSR RDE 3.4.1 07/08/2021 for the years 2018, 2019, and 2020); data prepared by the Screening Analysis and Monitoring Unit of the Australian Institute of Health and Welfare. Women who are eligible for screening comprise the estimated resident population, minus an estimate of the number of women who have had a hysterectomy and the number of women enrolled in the Compass trial, consistent with routine AIHW reports (1,3,37-39).

Percent is age-standardised across women aged 25-74, using the Australia 2001 standard population (15). Age-specific results are based on age at the end of the year being reported.

During the period when women are transitioning from cytology-based screening (screening done prior to 1st December 2017) and primary HPV screening (1st December 2017 onwards), women are considered up to date with recommended screening if they had either a primary cytology test in the previous two years, or a primary HPV test in the previous five years. In practice, the criteria of a primary cytology test in the previous two years only applies to the measure for 2018, as by 31st December 2019 more than two years had elapsed since the NCSP transitioned to primary HPV screening, so it was no longer possible to have had a primary cytology test in the previous two years. Additionally, as fewer than five years have elapsed since the NCSP transitioned to primary HPV screening, any woman with at least one primary HPV test would be considered up to date.

Data on Indigenous status are not yet sufficiently complete on the NCSR to allow reporting by Indigenous status. Given cervical cancer incidence rates are much higher among Indigenous women, and cervical screening is critical to reduce cervical cancer incidence in the nearer term, understanding and reporting screening coverage in Indigenous women is critical to achieving timely elimination among Indigenous women. There have been earlier studies of cervical screening coverage in Indigenous women, in the pre-renewed NCSP, based on analyses of ad hoc linked data for Qld, NSW, and the NT (18,42,43). In all three of these jurisdictions, Indigenous women were less likely to have been screened in the previously recommended interval of two years, and over a longer interval of five years (data for five years only reported for Qld and NSW).

The proportion of women who are up to date with screening was expected to remain approximately stable in 2018 and 2019, then naturally increase in 2020 and 2021.  This is because by the end of 2020 and 2021, the proportion who are up to date with screening will include anyone with an HPV test in the previous three and four years, respectively, as no women who have had their first HPV test will become overdue until at least December 2022. Data from the cytology-based NCSP suggest that the proportion of women screened continues to increase over three and five-year periods compared to a two-year period (45)

The proportion of women aged 70-74 years who are up to date was initially very small, and much lower than for other age groups, reflecting that prior to December 2017 screening was not actively recommended for this age group, and therefore that most women in this age group would have already been discharged from screening. As occurred for other groups, the proportion in this age group who are up to date has increased over time, but the increase was larger in this group than any other.  Increasingly women in this age group comprise those who have been recommended to attend for an exit test between the age of 70-74 years rather than to cease screening after 69 years (and by the end of 2022, all women in the 70-74 year age group will have reached the age of 70 after the recommendation for an exit test between 70-74 years was introduced). Conversely, the increase has been slower in those aged 25-29 years. While women who turned 25 more recently have had less time to have a test than those who were aged 25-74 years over the whole period (for example 1-2 years by the end of 2021 for those who turned 25 in 2020, compared to just over 4 years for those aged between 25-74 years over the whole time period), it is not the intent that women wait several years to have their first screening test.

The results in this report do not yet reflect the availability of self-collection as a choice for all people eligible for screening (which only became available in July 2022). It is anticipated that the national scale-up of this choice could help to increase equity in screening participation and may be particularly helpful in reaching women living in very remote areas, who had the lowest uptake on this measure.

The estimates here are not directly comparable with estimates in routine AIHW reports, as the estimates here include HPV tests performed for any purpose (including for symptoms, follow-up of a previous abnormality, at colposcopy, or any other purpose, consistent with monitoring conducted up until 2019), to capture all of those who are engaged with screening or being followed up in some way.

The hysterectomy prevalence estimates that are used to derive the population eligible for cervical screening are from an AIHW analysis of National Hospital Morbidity Database, and so consistent with other reports, however these estimates are not broken down by state/territory, remoteness area, or area-level SES. Potentially the prevalence of hysterectomy does vary across these strata, so using national age-specific estimates may under- or over-estimate the population who are eligible for screening in some cases.