Recruitment Strategies, Response Rates, and Non-Response Patterns in a Nationwide Registry-Based PRO Survey of Cancer Survivors and the General Population: The SURV-ICE Cohort

Background: Population-based studies using patient-reported outcomes provide important insights into health-related quality of life (HRQoL) and the long-term impact of cancer and its treatment. Declining response rates and potential non-response bias have presented methodological challenges, particularly in registry-based surveys including both cancer survivors and population controls. The SURV-ICE study was established to assess HRQoL and health literacy among cancer survivors in Iceland while evaluating recruitment processes and participation patterns in a nationwide mixed-mode survey. Methods: SURV-ICE is a nationwide, population-based cross-sectional survey conducted in Iceland in 2025. Adults diagnosed with invasive cancer between 2014 and 2024 were identified through the Icelandic Cancer Registry and invited alongside an age- and gender-matched control group sampled from national registers. Participants completed validated EORTC instruments. Recruitment used a mixed-mode strategy including postal invitations, web-based and paper questionnaires, electronic reminders via the national health portal, and targeted telephone follow-up. Results: Among 10,005 cancer survivors 5489 (54.9%) responded to the questionnaires and among 5663 controls 2297 (40.6%) responded to the questionnaires. In both groups participation peaked among individuals aged 60–79 years and was lowest among the youngest and oldest groups. Cancer survivors had higher odds of participation than controls (OR 1.84; 95% CI 1.72–1.97). Most responses followed the initial postal invitation and first electronic reminder. Data completeness was high (≥80% item completion in 95.7% of instruments). Conclusions: Nationwide registry-based recruitment for large-scale PRO research is feasible in Iceland and can achieve competitive response rates without incentives. SURV-ICE provides an infrastructure for future research on cancer survivorship, HRQoL, and health literacy.