Validation of the ICD-10 Diagnoses of Early-Onset Neonatal Infection in the Danish National Patient Register from 2010 to 2018

Purpose: To examine the accuracy of the diagnoses of early-onset neonatal infection in the Danish National Patient Register. Patients and Methods: All Danish neonates born after 35 weeks of gestation with an ICD10 diagnosis of sepsis or meningitis within the first week of life between 2010 and 2018 were identified. To examine the validity of the diagnoses, medical records were reviewed for 500 neonates diagnosed with sepsis and all 63 neonates diagnosed with meningitis. Proven infection was defined by bacterial pathogens identified from blood or cerebrospinal fluid. Probable sepsis was defined as at least 5 days of antibiotic treatment, two clinical signs of infection, and one abnormal blood biomarker. Probable meningitis was defined as at least 14 days of antibiotics, neurological affection, and cerebrospinal fluid analysis consistent with meningitis. Positive predictive values (PPVs) with 95% CI were estimated using the proven definition of infection as well as the criteria for either proven or probable infection. Results: The PPV for sepsis diagnoses using the proven definition was 0.04 (0.02, 0.06), while the PPV using both the proven and probable definition was 0.52 (0.45, 0.58). Sepsis diagnoses with a specified pathogen showed the highest PPV for proven sepsis at 0.36 (0.29, 0.43) and for proven or probable sepsis at 0.65 (0.58, 0.72). The PPV for meningitis diagnoses using the proven definition was 0.24 (0.13, 0.37), while the PPV using both the proven and probable definition was 0.38 (0.25, 0.52). Conclusion: We found a poor validity for the ICD10 diagnoses of early-onset neonatal infection in the Danish National Patient Register. This highlights that the diagnoses should be used cautiously in future research and surveillance and emphasises the need for supporting information on microbiological samples. Additionally, this highlights the importance of establishing a consensus definition of neonatal sepsis to improve diagnostic accuracy.