Uptake and performance of self-collection offered through primary care to all eligible participants in a national cervical screening programme in Australia: a retrospective cohort study

BACKGROUND: Human papillomavirus (HPV) testing of self-collected samples can improve uptake of cervical screening without compromising diagnostic yield. However, real-world evidence from population-based screening programmes remains scarce. We aimed to evaluate the effect of Australia's expansion of self-collection eligibility criteria on self-collection uptake and compare the detection of histologically verified high-grade lesions and cancer between self-collected and clinician-collected samples among individuals directly referred for colposcopy. METHODS: This retrospective cohort study was conducted as part of ongoing quality assurance and safety monitoring of the Australian National Cervical Screening Program, which expanded self-collection eligibility to all people with a cervix (herein referred to as women) aged 25-74 years on July 1, 2022, after initially offering self-collection only to women aged 30 years and older who were at least 2 years overdue or never screened through primary care when it transitioned to primary HPV testing on Dec 1, 2017. We extracted data from women aged between 24 years 9 months and 74 years enrolled in Australia's National Cancer Screening Register. We calculated uptake of self-collected samples as the proportion of all valid HPV tests for each quarter in a calendar year between Dec 1, 2017, and Dec 31, 2023. We compared the detection of high-grade lesions and cancer between self-collected and clinician-collected samples in women referred for colposcopy between July 1, 2022, and June 30, 2023, using multivariable logistic regression. We adjusted analyses for age, socioeconomic status, geographical remoteness, and screening status. FINDINGS: Uptake of self-collected samples steadily increased after the eligibility criteria were expanded in July, 2022, from 1·2% in the second quarter of 2022 to 26·9% in the fourth quarter of 2023. Uptake was highest among women who were more than 10 years overdue for screening (51·9%), those living in very remote (53·9%) and disadvantaged areas (≤29·1%), and those aged 70-74 years (33·5%). Between Dec 1, 2017, and June 30, 2023, a total of 4 926 713 women had a valid HPV test, with 484 622 (9·8%) testing positive for HPV. Between July 1, 2022, and June 30, 2023, 421 511 women had a valid HPV test and 63 541 (15·1%) were positive for HPV. HPV positivity was significantly higher in self-collected than clinician-collected samples (16·4% vs 14·8%; p