Studies on brain abscess are hampered by single-centre design with limited sample size and incomplete follow-up. Thus, robust analyses on clinical prognostic factors remain scarce. This Danish nationwide, population-based cohort study included clinical details of all adults (≥18 years) diagnosed with brain abscess in the Danish National Patient Registry from 2007 through 2014 and the prospective clinical database of the Danish Study Group of Infections of the Brain covering all Danish departments of infectious diseases from 2015 through 2020. All patients were followed for 6 months after discharge. Prognostic factors for mortality at 6 months after discharge were examined by adjusted modified Poisson regression to compute relative risks (RR) with 95% confidence intervals (CI). Among 485 identified cases, the median age was 59 years (IQR 48-67) and 167 (34%) were female. The incidence of brain abscess increased from 0.4 in 2007 to 0.8 per 100,000 adults in 2020. Immuno-compromise was prevalent in 192/485 (40%) and the clinical presentation was predominated by neurological deficits 396/485 (82%), headache 270/411 (66%), and fever 208/382 (54%). The median time from admission until first brain imaging was 4.8 hours (IQR 1.4-27). Underlying conditions included dental infections 91/485 (19%) and ear-nose-throat infections 67/485 (14%), and the most frequent pathogens were oral cavity bacteria (59%), Staphylococcus aureus (6%), and Enterobacteriaceae (3%). Neurosurgical interventions comprised aspiration 356/485 (73%) or excision 7/485 (1%) and was preceded by antibiotics in 377/459 (82%). Fatal outcome increased from 29/485 (6%) at discharge to 56/485 (12%) 6 months thereafter. Adjusted RRs for mortality at 6 months after discharge was 3.48 (95% CI 1.92-6.34) for intraventricular rupture, 2.84 (95% CI 1.45-5.56) for immuno-compromise, 2.18 (95% CI 1.21-3.91) for age >65 years, 1.81 (95% CI 1.00-3.28) for abscess diameter >3 cm, and 0.31 (95% CI 0.16-0.61) for oral cavity bacteria as causative pathogen. Sex, neurosurgical treatment, antibiotics before neurosurgery, and corticosteroids were not associated with mortality. This study suggests that prevention of rupture of brain abscess is crucial. Yet, antibiotics may be withheld until neurosurgery, if planned within a reasonable time period (e.g. 24 hours), in some clinically stable patients. Adjunctive corticosteroids for symptomatic perifocal brain oedema was not associated with increased mortality.

To examine the positive predictive value (PPV) of International Classification version 10 (ICD-10) diagnosis codes for long coronavirus disease 2019 (long-COVID) in a Danish Health registry. Patients and Methods: This was a medical record review of all patients with a diagnosis code of long-COVID (DB948A) at all hospitals in the North Denmark Region from February 27, 2020 through June 30, 2021. Confirmed long-COVID was categorized as fulfillment of all three criteria: (1) a positive polymerase chain reaction (PCR) test for SARS-CoV-2 on a respiratory sample or a positive serum antibody test, (2) symptoms suggestive of long-COVID with no other diagnosis considered more likely, and (3) symptom duration >6 weeks.Results: A total of 306 patients were assigned a hospital diagnosis code for long-COVID corresponding to 1.4% of all SARS-CoV-2 positive individuals during the study period (n=21,727). Next, 40 patients were excluded due to incomplete diagnostic evaluation at time of record review leaving 266 patients for analysis. The patients had a median age of 51 years (interquartile range 43-60) and 175/ 266 (66%) were females. Long-COVID was confirmed in 249/266 yielding an overall PPV of 94% (95%CI: 90-96) and did not differ substantially according to most age groups, sex, previous hospitalization for COVID-19, or by using 12 weeks of symptom duration as cut-off. The PPV was low for children and adolescents (n=5), the very elderly (n=9), and those included by secondary long-COVID diagnoses (n=10). Conclusion:The overall PPV of diagnosis codes for long-COVID in the North Denmark Region was high and was likely suitable for future registry-based studies of long-COVID. Caution is advised at the extremes of age and secondary diagnosis codes.

Background and objectives:Epilepsy in patients with brain abscess is frequent but risk factors and prognosis remain undetermined. This study examined risk factors for epilepsy among survivors of brain abscess and associated prognosis.Methods:Nationwide, population-based healthcare registries were used to compute cumulative incidences and cause-specific adjusted hazard rate ratios (adj. HRRs) with 95% confidence intervals (CIs) for epilepsy among 30-day survivors of brain abscess from 1982 through 2016. Data was enriched with clinical details by medical record review of patients hospitalized from 2007 through 2016. Adjusted mortality rate ratios (adj. MRRs) were examined using epilepsy as a time-dependent variable.Results:The study included 1,179 30-day survivors of brain abscess among whom 323 (27%) developed new-onset epilepsy after a median of 0.76 years (interquartile range [IQR] 0.24-2.41). At admission for brain abscess, the median age was 46 years (IQR 32-59) in patients with epilepsy compared with 52 years (IQR 33-64) in those without epilepsy. The proportion of females was similar in patients with and without epilepsy (37%). Adj. HRRs for epilepsy were 2.44 (95% CI 1.89-3.15) for aspiration or excision of brain abscess, 2.37 (1.56-3.60) for alcohol abuse, 1.75 (1.27-2.40) for previous neurosurgery or head trauma, 1.62 (1.17-2.25) for stroke, and 1.55 (1.04-2.32) for age group 20-39 years. Cumulative incidences were increased in patients with alcohol abuse (52% vs 31%), aspiration or excision of brain abscess (41% vs. 20%), previous neurosurgery or head trauma (41% vs. 31%), and stroke (46% vs. 31%). Analysis using clinical details from medical record review of patients from 2007 through 2016 demonstrated adj. HRRs of 3.70 (2.24-6.13) for seizures at admission for brain abscess and 1.80 (1.04-3.11) for frontal lobe abscess. In contrast, adj. HRR was 0.42 (0.21-0.86) for occipital lobe abscess.Using the entire registry-based cohort, patients with epilepsy had an adj. MRR of 1.26 (1.01-1.57).Discussion:Important risk factors for epilepsy were seizures during admission for brain abscess, neurosurgery, alcoholism, frontal lobe abscess, and stroke. Epilepsy was associated with increased mortality. Anti-epileptic treatment may be guided by individual risk profiles and specialized follow-up is highlighted by increased mortality in survivors with epilepsy.