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

Abstract

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.