Acute Kidney Injury, the Present on Admission indicator (POA) and sex disparities: Observational study of inpatient real world data in a Swiss tertiary health care system

Background Regarding kidney disease, sex differences in epidemiology and clinical relevance have been reported. Related to absolute and relative changes of baseline creatinine, different criteria for staging may induce under-or over-diagnosis related to sex. At the largest Swiss provider of inpatient acute health care, a clinic decision support algorithm ensures exact staging of kidney disease (2012 KDIGO Clinical Practice Guideline). Coding of the indicator “Present On Admission” was introduced at this institution in 2018 to flag post-admission conditions. Objective We hypothesized sex differences in health care associated acute kidney injury. Defined indicators and the distribution of stages in acute kidney injury were analysed using the POA flag. Sex differences were reported. Methods Retrospective observational study. Routinely collected health data, Insel Group, Berne, Switzerland, 2019 and 2020 (121’757 cases) on the patient history and intensive care treatment duration, comorbidity levels, coded diagnoses, age and sex. Software and statistic: program R, version 4.1.1, standard deviation; median, interquartile range; prop.test; standardized mean difference. Results The reporting of post-admission diagnoses was associated with more interhospital transfers, intensive care stays, scores of severity and treatment intensity, mechanical ventilation, age, number of diagnoses, complexity level of the related cases and mortality. A weaker association could be observed for the female population. However, mortality was higher (stage III acute kidney injury 41.6%). Conclusion Using the POA-flag the results reflect the clinical situation of complications and comorbidities evolving unexpectedly. As our results show sex differences, i.e. a lower morbidity of female patients for each stage, but a higher mortality, a deeper evaluation of the implied sex differences in staging of kidney disease should follow. The general results confirm the necessity of a diagnosis-onset reporting in health statistic. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement The authors received no specific funding for this work ### 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 Ethics Committee of the Canton Bern approved our study KEK-Nr. Req-2018-00328 for the further use of coded, health-related personal data. Gesundheits-, Sozial- und Integrationsdirektion des Kantons Bern (GSI) Kantonale Ethikkommission Murtenstrasse 31 Hörsaaltrakt Pathologie, Eingang 43A, Büro H372 CH 3010 Bern 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 and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All relevant data are within the manuscript and its Supporting Information files.