Systematic collection of patient-reported outcome measures (PROMs) enables researchers to understand trends in clinical care, measure their effects on patient outcomes, and potentially devise interventions to optimise those outcomes . There are impediments to widespread population-based use of PROM surveys. PROM completion is subject to various patient-level factors such as perceived irrelevance of the survey instrument or that inordinate amounts of time required to complete the PROM, difficulty with an electronic mode of completion, and a variety of other phenomena (forgetfulness, differing priorities, procrastination) [2,3,4]. Therefore, strategies to maximise patient engagement and the completion of PROMs instruments are necessary for collection of robust and unbiased outcomes data . Previous studies have found that reminder emails are effective in increasing the response rate to web-based survey instruments [6, 7]. In a clinical trial setting, automatic reminders appear likely to positively impact completion and timeliness of PROM submission .
We sought to quantify the improvement in PROM return rate that a reminder email confers in a large population-based registry setting, without the explicit opt-in consent and active monitoring present in a trial. The Victorian Prostate Cancer Outcomes Registry (PCOR-Vic) is a population-wide clinical quality registry enrolling men with newly diagnosed prostate cancer . As of 2021, coverage is greater than 80% of the incident diagnoses in Victoria, Australia. It operates with an opt-off consent model, i.e., patients are notified that they will be entered into the registry unless they request not to be. PCOR-Vic administers the validated PROM instrument EPIC-26  (Expanded Prostate Cancer Index Composite—26) to patients approximately one year after their initial prostate cancer diagnosis/treatment, predominantly via email contact. Further, we aimed to explore the effect on response rate of patient age at PROM, socioeconomic status, and the day of the week the initial contact email was sent.