Multi-source coherence analysis of the first European multi-centre cohort study for cancer prevention in people experiencing homelessness: a data quality study

Background and objective People experiencing homelessness (PEH) face significant health challenges and disparities in healthcare access due to barriers such as unstable housing, limited resources, and social stigma. In response, the European Union has initiated efforts to address these disparities. The CANCERLESS project, part of this initiative, has created the first European multi-centre dataset for cancer prevention in PEH. This work aims to evaluate and describe the heterogeneity of PEH across pilot sites and to provide data quality metrics for reliable future research.

The dataset comprises 652 cases: 142 from Vienna, 158 from Athens and Thessaloniki, 197 from Madrid, and 155 from the United Kingdom. All participants fit classifications from the European Typology of Homelessness and Housing Exclusion. This longitudinal study collected questionnaires at baseline, four weeks, and at the end of the intervention. The 180-question survey covered socio-demographic data, overall health, mental health, empowerment, and interpersonal communication. Data variability was assessed using information theory and geometric methods to analyse discrepancies in distributions and completeness across the dataset.

Significant variability was found among the four pilot countries, both overall and within specific sections, except for the health section. Madrid showed the largest discrepancies, with a high number of missing values related to interpersonal communication and healthcare service use.

Health data may be comparable across the four countries, but further analysis should account for location-specific differences. This study underscores the heterogeneity among PEH and the critical need for data quality assessments to inform future research and policymaking in this field. Competing Interest Statement The authors have declared no competing interest. Funding Statement The CANCERLESS project has been funded by the European Commission's Programme Horizon 2020 under the Grant Agreement 965351. This publication reflects the author's views. The European Commission is not responsible for any use that may be made of the information it contains. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Data used in this study belongs to the CANCERLESS project. Each pilot of the study have obtained a positive ethical vote. Universitat Politecnica de Valencia have approved the use of the data management with number: P11_25_07_2022. The Ethics Committee of the Medical University of Vienna granted approval for the overall study. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data Availability Data availability is under discussion by the consortium partners to follow open access policies