Geographic inequities in patient-reported outcome measures in clinical trials of selected solid tumours in Europe: findings from EuroACT

Background Geographic inequities in clinical trial access and the inconsistent application of Patient-Reported Outcome Measures (PROMs) compromise patient-centred care in oncology across Europe. We aimed to quantify geographic disparities and identify trial-level characteristics associated with PROM documentation in registry outcome fields in interventional clinical trials and observational studies of selected solid tumours. Methods We analysed data from ClinicalTrials.gov , EudraCT, and Clinical Trials Information System registries covering trials conducted in Europe for twelve solid tumour types. Trials were categorised by design, participant characteristics, PROM documentation in registry outcome fields, and sponsor type. Geographic inequality was quantified using a GDP-ranked concentration curve and concentration index, with a population-weighted Gini coefficient as a sensitivity analysis. Multivariable logistic regression assessed characteristics associated with registry-documented PROM inclusion. Results We identified 20,658 trials (15,528 interventional, 5,130 observational). Registry-documented PROMs were identified in 24.8% (n = 3,858) of interventional trials and 14.8% (n = 758) of observational studies. Among 2,264 completed interventional trials with registry-documented PROMs, 952 had an eligible linked publication, 948 had an available abstract, and 218 had a detected PROM mention, representing 23.0% of trials with an available abstract and 9.6% of the full completed registry-PROM cohort. Substantial geographic inequity existed (GDP-ranked concentration index 0.393; population-weighted Gini coefficient 0.446). Trials with at least one site in Northern (OR 1.46, 95% CI 1.31–1.62) or Western Europe (OR 1.39, 1.25–1.54) were more likely to include PROMs, whereas trials with Central and Eastern European site presence were slightly less likely (OR 0.86, 0.76–0.97), although this association was not statistically significant after multiple imputation (OR 0.92, 0.81–1.04). Interventional, randomised, larger scale (>10 sites), and trials initiated after 2020 were associated with higher registry-documented PROM inclusion (p < 0.0001). Trials enrolling defined adult populations were significantly more likely to include PROMs compared with mixed-age or paediatric populations. Conclusion This analysis highlights substantial geographic and economic disparities in the distribution of registered trial sites and in registry-documented PROM inclusion in clinical trials for solid tumours across Europe. Solely non-commercial and commercial sponsorship did not differ significantly after multivariable adjustment. The observational findings do not establish causal effects of sponsorship on PROM incorporation, collection, reporting, or patient benefit. Persistent inequities in lower-income European regions underscore the need for improved registry documentation, targeted policy initiatives, resource allocation, and capacity-building in academia to strengthen PROM integration.