The density of routinely collected neurology data depends on patient visit type: an investigation using the Observational Medical Outcomes Partnership Common Data Model

Background The Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM) is a standardised framework for organising healthcare data. This study investigates the practicality of using the OMOP CDM to analyse data on neurology patients.

An outpatient neurology patient cohort was defined on the basis of having attended at least one neurology outpatient appointment between 01 April 2022 and 31 March 2023 (n=23,862). All data collected at visits made by this cohort between 01 April 2021 to 31 March 2024 was extracted. The cohort was then divided into 4 sub-cohorts according to appointment types attended: outpatient appointment(s) only (n=15,255); outpatient appointment(s) and inpatient stay(s) (n=2750); outpatient appointment(s) and emergency department attendance(s) (n=1658); outpatient appointment(s), inpatient stay(s) and emergency department attendance(s) (n=4199).

We found there to be more OMOP-mapped data available for patients who had at least one inpatient stay or emergency department attendance than for those with only outpatient appointments. Notably, an average of 0 out of 100 patients in the outpatient only sub-cohort had a record of a condition, compared to 100 out of 100 patients in the sub-cohort with outpatient appointments, emergency attendances and inpatient stays.

Neurology outpatients have far less data recorded than inpatients or patients attending ED. This disparity arises from the lack of outpatient diagnostic coding and impairs the advancement of research in this area. What is already known on this topic the OMOP common data model (CDM) is being adopted by the NHS to provide a uniform structure to the data within the NHS Secure Data Environments to support research. We know that outpatient coding is not mandated so diagnoses at outpatient appointments are not regularly recorded in EHRs. What this study adds we investigate the variable volume of data available for research through a secondary care dataset that has been converted to the OMOP CDM. We show that outpatients have far less data recorded than inpatients or patients attending ED, in terms of both volume and type of data. How this study might affect research, practice or policy this study highlights the need for data systems such as SDEs to be based on data which is complete. We also highlight the importance of ensuring that data recording for outpatients is as complete as it is for inpatients and ED. Competing Interest Statement The authors have declared no competing interest. Funding Statement Fran Biggin is funded by The Engineering and Physical Sciences Research Council Impact Acceleration Account (EP/X525583/1). For the purpose of Open Access, the author has applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission. The funders were not involved in study design, data collection, interpretation or writing of the report. 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: The Research and Innovation department of Lancashire Teaching Hospitals NHS Foundation trust gave approval for this work under a Service Evaluation agreement SE-475. The Service Evaluation process at LTHTR includes an evaluation of privacy protection and provides a conclusion as to whether a study requires further ethical review. The text of the registration agreement reads: "Service Evaluation is defined as being conducted solely to define or judge current care and does not require ethical review". 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 used in the present work are not available for public sharing due to patient confidentiality. Access to the data may be considered under appropriate data-sharing agreements and ethical approvals.