Effect of Patient Characteristics on Uptake of Screening Using a Mailed Human Papillomavirus Self-sampling Kit: A Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE: Mailing human papillomavirus (HPV) self-sampling kits increases cervical cancer screening participation, but effects may differ across subpopulations. Subpopulation data can inform US health care system implementation. OBJECTIVE: To identify patient characteristics that modify effectiveness of a mailed kit intervention at increasing screening. DESIGN, SETTING, AND PARTICIPANTS: This was a secondary analysis of data from the Home-Based Options to Make Cervical Cancer Screening Easy (HOME) randomized clinical trial conducted from 2014 to 2018 at Kaiser Permanente Washington. Data analysis was performed from March 2018 to May 2022. Individuals aged 30 to 64 years with female sex, health plan enrollment longer than 3 years and 5 months, a current primary care clinician, and no Papanicolaou test within the prior 3 years and 5 months were identified through electronic medical records and randomized (1:1) to the control or intervention group. INTERVENTIONS: The control group received usual care Papanicolaou screening reminders and outreach. The intervention group received usual care plus an unsolicited mailed HPV self-sampling kit. MAIN OUTCOMES AND MEASURES: Screening uptake was captured within 6 months after randomization. Baseline patient characteristics (age, race, ethnicity, travel time to clinic, income, body mass index, tobacco use, health plan enrollment duration, time since last Papanicolaou test, mammography, comorbidities, and colorectal cancer screening adherence) were extracted from the electronic medical record. RESULTS: Of 19 734 individuals (mean [SD] age, 50.1 [9.5] years; 14 129 [71.6%] White), 9843 were randomized to the intervention group, and 9891 were randomized to the control group. Screening uptake was 26.3% (2592 of 9843 individuals) in the intervention group vs 17.4% (1719 of 9891 individuals) in the control group (relative risk [RR], 1.51; 95% CI, 1.43-1.60). Although absolute differences in uptake by group varied little by screening history, relative effects were greater with longer vs shorter time since last Papanicolaou test (no prior Papanicolaou test: RRs, 1.85-3.25; ≥10 years: RR, 2.78; 5-10 years: RRs, 1.69-1.86; <5 years: RRs 1.29-1.37). Relative effects were greater in participants overdue (RR, 2.03; 95% CI, 1.73-2.38) vs up-to-date with mammography (RR, 1.53; 95% CI, 1.41-1.67), although absolute difference was greater in the up-to-date group. Differences by age were not significant, with RRs of 1.33 to 1.48 across 5-year age groups in participants 30 to 54, vs 1.60 (95% CI, 1.40-1.82) in participants 55 to 59 and 1.77 (95% CI, 1.56-2.01) in participants 60 to 64 years. Among those mailed kits, there were differences in kit use vs in-clinic screening by age, race, plan enrollment duration, underscreening duration, and colorectal cancer screening adherence. CONCLUSIONS AND RELEVANCE: In this secondary analysis of a randomized clinical trial, clinically important improvements in screening uptake were observed for all subgroups. Differences in magnitude of intervention effect and kit use highlighted opportunities to optimize HPV self-sampling for priority groups. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02005510