127 Cervical cancer screening among marginalized women The screening method used was liquid based cytology sampling. The samples were analysed using both a HR-HPV test (COBAS 6800® HR-HPV, Roche) and cytology (ThinPrep® PAP-test, examined with computer assisted screening on the ThinPrep® Integrated Imager by Hologic) on each sample. The Dutch CSP uses the same laboratory methods.5 In the Netherlands the Papanicolaou (Pap) classification is used to score the test outcome. A participant was considered being a screen-positive, when they tested positive for high-risk human papilloma virus (HR-HPV) and showed cytological abnormalities (≥Pap-2). This corresponds with the National Health Service Cervical Screening Program of the United Kingdom as: ≥HR-HPV positive and borderline changes in the squamous/endocervical cells, and with the American Bethesda-classification as: ≥ atypical squamous cells of uncertain significance. 13,14 Participants were informed of their test results by means of consultations, text messages and phone calls; usually directly to the participant, but occasionally to their care providers. Referral to a gynaecologist was done by the streetdoctor, or if present, the own GP. A public health safety-net team served as backup, whenever women needed to be located for follow-up but did not show at their appointment. Data management The medical team registered details of the procedure in the routine medical files of the participant. At inclusion the women gave consent to share their medical record for research. For data-extraction, data were anonymized by coding all study participants and removing all information that would enable researchers to trace back the data to a single individual. HR-HPV status and cytological classifications were translated into binary outcomes, respectively negative/positive and normal/abnormal smear. Age (in years) and the inclusion location were extracted as well. The inclusion method was coded as indirect or as direct. Anecdotal reasons for refusal to participate in the study were registered for the few women who declined participation and were willing to the reason. Data were stored and saved in compliance with guidelines of Good Research Practices. Upfront this study was approved by the Ethics Committee of the Leiden University Medical Centre and was conducted in accordance with the Declaration of Helsinki. Power analysis The Dutch CSP is coordinated by five regional screening organizations, making screening data available and insightful on specific regions. ‘Stichting Bevolkingsonderzoek ZuidWest’ is the designated screening organization for Rotterdam concerned with the southwest region of the Netherlands. Of all participating women in the southwest region 3.4% were found to be screen-positive in 2018.15 A prior study on homeless women presented a percentage of 18% screen-positive women.11 Using this information a power 5
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