Automated Classification of Free-Text Radiology Reports: Using Different Feature Extraction Methods to Identify Fractures of the Distal Fibula.

PURPOSE: Radiology reports mostly contain free-text, which makes it challenging to obtain structured data. Natural language processing (NLP) techniques transform free-text reports into machine-readable document vectors that are important for creating reliable, scalable methods for data analysis. The aim of this study is to classify unstructured radiograph reports according to fractures of the distal fibula and to find the best text mining method. MATERIALS & METHODS: We established a novel German language report dataset: a designated search engine was used to identify radiographs of the ankle and the reports were manually labeled according to fractures of the distal fibula. This data was used to establish a machine learning pipeline, which implemented the text representation methods bag-of-words (BOW), term frequency-inverse document frequency (TF-IDF), principal component analysis (PCA), non-negative matrix factorization (NMF), latent Dirichlet allocation (LDA), and document embedding (doc2vec). The extracted document vectors were used to train neural networks (NN), support vector machines (SVM), and logistic regression (LR) to recognize distal fibula fractures. The results were compared via cross-tabulations of the accuracy (acc) and area under the curve (AUC). RESULTS: In total, 3268 radiograph reports were included, of which 1076 described a fracture of the distal fibula. Comparison of the text representation methods showed that BOW achieved the best results (AUC = 0.98; acc = 0.97), followed by TF-IDF (AUC = 0.97; acc = 0.96), NMF (AUC = 0.93; acc = 0.92), PCA (AUC = 0.92; acc = 0.9), LDA (AUC = 0.91; acc = 0.89) and doc2vec (AUC = 0.9; acc = 0.88). When comparing the different classifiers, NN (AUC = 0,91) proved to be superior to SVM (AUC = 0,87) and LR (AUC = 0,85). CONCLUSION: An automated classification of unstructured reports of radiographs of the ankle can reliably detect findings of fractures of the distal fibula. A particularly suitable feature extraction method is the BOW model. KEY POINTS: · The aim was to classify unstructured radiograph reports according to distal fibula fractures.. · Our automated classification system can reliably detect fractures of the distal fibula.. · A particularly suitable feature extraction method is the BOW model.. CITATION FORMAT: · Dewald CL, Balandis A, Becker LS et al. Automated Classification of Free-Text Radiology Reports: Using Different Feature Extraction Methods to Identify Fractures of the Distal Fibula. Fortschr Röntgenstr 2023; 195: 713 - 719.

Low Serum Cholinesterase Identifies Patients With Worse Outcome and Increased Mortality After TIPS.

Transjugular intrahepatic portosystemic shunt (TIPS) is an effective treatment for portal hypertension-related complications. However, careful selection of patients is crucial. The aim of this study was to evaluate the prognostic value of serum cholinesterase (CHE) for outcomes and mortality after TIPS insertion. In this multicenter study, 389 consecutive patients with cirrhosis receiving a TIPS at Hannover Medical School, University Hospital Essen, or Medical University of Vienna were included. The Hannover cohort (n = 200) was used to initially explore the role of CHE, whereas patients from Essen and Vienna served as a validation cohort (n = 189). Median age of the patients was 58 years and median Model for End-Stage Liver Disease (MELD) score was 12. Multivariable analysis identified MELD score (hazard ratio [HR]: 1.16; P < 0.001) and CHE (HR: 0.61; P = 0.008) as independent predictors for 1-year survival. Using the Youden Index, a CHE of 2.5 kU/L was identified as optimal threshold to predict post-TIPS survival in the Hannover cohort (P < 0.001), which was confirmed in the validation cohort (P = 0.010). CHE < 2.5 kU/L was significantly associated with development of acute-on-chronic liver failure (P < 0.001) and hepatic encephalopathy (P = 0.006). Of note, CHE was also significantly linked to mortality in the subgroup of patients with refractory ascites (P = 0.001) as well as in patients with high MELD scores (P = 0.012) and with high-risk FIPS scores (P = 0.004). After propensity score matching, mortality was similar in patients with ascites and CHE < 2.5 kU/L if treated by TIPS or by paracentesis. Contrarily, in patients with CHE ≥ 2.5 kU/L survival was significantly improved by TIPS as compared to treatment with paracentesis (P < 0.001). Conclusion: CHE is significantly associated with mortality and complications after TIPS insertion. Therefore, we suggest that CHE should be evaluated as an additional parameter for selecting patients for TIPS implantation.

Epidemiology and infection control of carbapenem resistant Acinetobacter baumannii and Klebsiella pneumoniae at a German university hospital: a retrospective study of 5 years (2015-2019).

BACKGROUND: Carbapenem resistant (CR) Klebsiella pneumoniae (Kp) and Acinetobacter baumannii (Ab) are emerging multidrug resistant bacteria with very limited treatment options in case of infection. Both are well-known causes of nosocomial infections and outbreaks in healthcare facilities. METHODS: A retrospective study was conducted to investigate the epidemiology of inpatients with CR Kp and CR Ab in a 1500-bed German university hospital from 2015 to 2019. We present our infection control concept including a weekly microbiologic screening for patients who shared the ward with a CR Kp or CR Ab index patient. RESULTS: Within 5 years, 141 CR Kp and 60 CR Ab cases were hospitalized corresponding to 118 unique patients (74 patients with CR Kp, 39 patients with CR Ab and 5 patients with both CR Ab and CR Kp). The mean incidence was 0.045 (CR Kp) and 0.019 (CR Ab) per 100 inpatient cases, respectively. Nosocomial acquisition occurred in 53 cases (37.6%) of the CR Kp group and in 12 cases (20.0%) of the CR Ab group. Clinical infection occurred in 24 cases (17.0%) of the CR Kp group and in 21 cases (35.0%) of the CR Ab group. 14 cases (9.9%) of the CR Kp group and 29 cases (48.3%) of the CR Ab group had a history of a hospital stay abroad within 12 months prior to admission to our hospital. The weekly microbiologic screening revealed 4 CR Kp cases caused by nosocomial transmission that would have been missed without repetitive screening. CONCLUSIONS: CR Kp and CR Ab cases occurred infrequently. A history of a hospital stay abroad, particularly in the CR Ab group, warrants pre-emptive infection control measures. The weekly microbiologic screening needs further evaluation in terms of its efficiency.

Safety and feasibility of transjugular intrahepatic portosystemic shunt in elderly patients with liver cirrhosis and refractory ascites.

BACKGROUND & AIMS: The management of patients with refractory ascites (RA) is challenging, particularly at higher age. Transjugular intrahepatic portosystemic shunt (TIPS) is an established treatment for RA, but safety data in elderly patients are rare. Our aim was to evaluate the safety and feasibility of TIPS in elderly patients with RA. METHODS: Overall, 160 consecutive cirrhotic patients receiving a TIPS for RA at Hannover Medical School between 2012 and 2018 were considered for this retrospective analysis. Periinterventional complications such as acute-on-chronic liver failure (ACLF) as well as survival were compared between patients <65 and ≥65 years. Propensity score matching was conducted to match elderly TIPS patients and patients treated with paracentesis. RESULTS: A number of 53 out of the 160 patients were ≥65 years (33%). Periinterventional course in those ≥65 years appeared to be slightly more complicated than in <65 years as reflected by a significantly longer hospital stay (p = 0.030) and more ACLF-episodes (21% vs. 9%; p = 0.044). 28-day mortality was similar between both groups (p = 0.350), whereas survival of the younger patients was significantly higher at 90 days (p = 0.029) and numerically higher at 1 year (p = 0.171). In the multivariate analysis age ≥65 years remained an independent predictor for 90-day mortality (HR: 2.58; p = 0.028), while it was not associated with 28-day and 1-year survival. Importantly, after matching for potential confounders 1-year survival was similar in elderly patients if treated with TIPS or paracentesis (p = 0.419). CONCLUSIONS: TIPS placement in elderly patients with RA appears to be slightly more complicated compared to younger individuals, but overall feasible and at least not inferior to paracentesis.

Frequency, characteristics and impact of multiple consecutive nosocomial infections in patients with decompensated liver cirrhosis and ascites.

BACKGROUND: Nosocomial infections are a particular threat for patients with liver cirrhosis. It is not uncommon that individuals develop even several consecutive infections during a single hospital stay. We aimed to investigate the impact and characteristics of multiple, consecutive nosocomial infections. METHODS: A total of 514 consecutive patients with liver cirrhosis and ascites were included and followed up for 28 days for nosocomial infection, death or liver transplantation (LTx). Laboratory values were assessed at the time of hospitalization as well as at the onset of each new infectious episode. RESULTS: 58% (n = 298) of the patients developed at least one nosocomial infection and in 23% (n = 119) even multiple infections were documented during a single hospital stay. Consecutive infections usually occurred shortly after the previous episode. Spontaneous bacterial peritonitis (SBP) was the most common infection. However, the proportion of SBP declined from 43% at the first to only 31% at the third nosocomial infection (p = 0.096). In contrast, the likelihood for other, less common types of infection such as blood stream infections increased. Third nosocomial infections were also more likely to be linked to the detection of fungal pathogens (21% vs. 52%; p = 0.001). Each additional infectious episode had a dramatic detrimental impact on LTx-free survival that was independent from the stage of liver disease (adjusted-HR: 6.76, p = 0.002 for first nosocomial infection; adjusted-HR: 14.69, p<0.001 for second nosocomial infection; adjusted-HR: 24.95, p<0.001 for third nosocomial infection). CONCLUSION: In patients with decompensated liver cirrhosis LTx-free survival significantly decreases with every consecutive infectious episode. Development of prevention strategies is urgently required.

Implementing LOINC - Current Status and Ongoing Work at a Medical University.

The Logical Observation Identifiers, Names and Codes (LOINC) is a common terminology used for standardizing laboratory terms. Within the consortium of the HiGHmed project, LOINC is one of the central terminologies used for health data sharing across all university sites. Therefore, linking the LOINC codes to the site-specific tests and measures is one crucial step to reach this goal. In this work we report our ongoing efforts in implementing LOINC to our laboratory information system and research infrastructure, as well as our challenges and the lessons learned. 407 local terms could be mapped to 376 LOINC codes of which 209 are already available to routine laboratory data. In our experience, mapping of local terms to LOINC is a widely manual and time consuming process for reasons of language and expert knowledge of local laboratory procedures.

Systemic arterial blood pressure determines the therapeutic window of non-selective beta blockers in decompensated cirrhosis.

BACKGROUND: The safety of non-selective ß-blockers in patients with advanced cirrhosis has been questioned in recent years. It was hypothesised that there is a particular therapeutic window. However, the specific limits still need to be determined. AIM: To evaluate potential limits of the therapeutic window of non-selective ß-blocker therapy in patients with cirrhosis and ascites METHODS: The impact of non-selective ß-blockers on 28-day transplant-free survival was analysed in a cohort of 624 consecutive patients with decompensated cirrhosis and ascites. Three potential limits were investigated: spontaneous bacterial peritonitis, acute-on-chronic liver failure, mean arterial blood pressure ≤ 82 and < 65 mm Hg. RESULTS: Treatment with non-selective ß-blockers was associated with a higher 28-day transplant-free survival in the overall cohort (hazard ratio: 0.621; P = .035) as well as in patients with acute-on-chronic liver failure (hazard ratio: 0.578; P = .031) and those with spontaneous bacterial peritonitis (hazard ratio: 0.594; P = .073). In contrast, survival benefits were markedly attenuated in patients with a mean arterial blood pressure ≤ 82 mm Hg and completely lost in those with mean arterial blood pressure < 65 mm Hg (P = .536). In spontaneous bacterial peritonitis patients with a mean arterial blood pressure < 65 mm Hg non-selective ß-blocker treatment was associated with renal impairment. Of note, among those with a mean arterial blood pressure ≥ 65 mm Hg non-selective ß-blocker intake was consistently associated with superior transplant-free survival (hazard ratio: 0.582; P = .029) irrespective of the presence of spontaneous bacterial peritonitis (hazard ratio: 0.435; P = .028) or acute-on-chronic liver failure (hazard ratio: 0.480 P = .034). CONCLUSIONS: Ascites, acute-on-chronic liver failure and spontaneous bacterial peritonitis do not limit the safe use of non-selective ß-blockers in patients with cirrhosis. Mean arterial blood pressure might represent a better indicator to determine the therapeutic window of non-selective ß-blocker treatment.

Sustained impact of nosocomial-acquired spontaneous bacterial peritonitis in different stages of decompensated liver cirrhosis.

BACKGROUND & AIMS: Bacterial infections, in particular a spontaneous bacterial peritonitis (SBP), are a major threat in patients with liver cirrhosis. Recently, it has been shown that the impact on mortality might be underestimated by established risk-scores. Onset of infection was suggested to define a distinct stage of cirrhosis. However, it remains unclear whether all stages of decompensated cirrhosis are equally affected. Moreover, if there is such a distinct stage, it must be determined whether it is reversible after the infection has resolved. In this study we aimed to further analyze the impact of a current as well as a resolved SBP in different stages of decompensated liver cirrhosis. METHODS: A number of 579 patients with liver cirrhosis and ascites were included. MELD-score was used to determine the stage of liver disease. Low (<15), intermediate (15-25) and high (>25) MELD-groups were compared. Patients were followed up for 90 days. Primary endpoint was overall mortality. Statistical analyses were performed using the log-rank test, Cox regression and competing risk analysis. RESULTS: Mortality was significantly higher in patients with nosocomial-acquired SBP (nSBP) compared to patients without SBP (p<0.001;HR = 2.05). However, the most prominent difference in mortality was documented in the intermediate MELD-group (nSBP: p = 0.02;HR = 2.10). Importantly, mortality in nSBP patients remained increased even after the initial nSBP episode had resolved (p<0.01;HR = 1.90). Again, this was only significant in those with intermediate MELD-scores (p = 0.02;HR = 2.28). While a current as well as a resolved nSBP were significantly linked to a higher mortality, neither of them did increase the likelihood for liver transplantation. CONCLUSIONS: Development of nSBP is independently associated with increased mortality supporting the concept of a distinct status of cirrhosis. Importantly, the prognosis remains unfavorable even after resolution of nSBP. This could be particularly relevant for patients with intermediate MELD-scores, who have limited chances for a donor liver.

Implementing LOINC: Current Status and Ongoing Work at the Hannover Medical School.

The Logical Observation Identifiers, Names and Codes (LOINC) is a common terminology used for standardizing laboratory terms. Within the HiGHmed consortium, LOINC is used as a central terminology for health data sharing across all university hospital sites. Therefore, linking the LOINC codes to the site-specific tests and measures is one crucial step to reach this goal. In this work we report our ongoing work in implementing LOINC to the laboratory information system, our challenges and lessons learned.

Association Between Type 2 Diabetes Mellitus, HbA1c and the Risk for Spontaneous Bacterial Peritonitis in Patients with Decompensated Liver Cirrhosis and Ascites.

INTRODUCTION: Type 2 diabetes mellitus (DM) is a frequent comorbidity among patients with liver cirrhosis. However, data regarding the impact of DM on spontaneous bacterial peritonitis (SBP) are quite limited. Our aim was to analyze the impact of DM and HbA1c values on the incidence of SBP and mortality in patients with liver cirrhosis and ascites. METHODS: A number of 475 consecutive patients with liver cirrhosis and ascites were analyzed. Presence of DM as well as HbA1c was assessed at the time of the first paracentesis. Patients were followed up for a mean of 266 days. Primary endpoints were SBP development and mortality. RESULTS: Overall, 118 (25%) patients were diagnosed with DM. DM patients had an increased risk for developing a SBP during follow-up (HR: 1.51; p = 0.03). SBP incidence was particularly high in DM patients with HbA1c values ≥6.4%, significantly higher than in DM patients with HbA1c values <6.4% (HR: 4.21; p = 0.0002). Of note, DM patients with HbA1c <6.4% at baseline had a similar risk for SBP as those without DM (HR: 0.93; p = 0.78, respectively). After excluding all patients who were eligible for secondary antibiotic prophylaxis, HbA1c ≥6.4% but neither bilirubin nor ascites protein level were associated with primary SBP development in the multivariate analysis (p = 0.003). CONCLUSIONS: Individuals with liver cirrhosis and concomitant DM have a higher risk for developing a SBP. HbA1c values may be useful to further stratify the risk for SBP among DM patients, which may help to identify those who benefit from antibiotic prophylaxis.

Dose-dependent impact of proton pump inhibitors on the clinical course of spontaneous bacterial peritonitis.

BACKGROUND & AIMS: Spontaneous bacterial peritonitis is a severe complication in patients with cirrhosis leading to acute kidney injury, hepatic encephalopathy and a high mortality. In this study, we aimed to investigate the impact of proton pump inhibitors and the potential relevance of the taken dosage on the incidence and clinical course of spontaneous bacterial peritonitis. METHODS: Overall, 613 consecutive patients with decompensated cirrhosis were included. All patients were carefully evaluated for proton pump inhibitors intake including the applied dosage and were further followed up for spontaneous bacterial peritonitis development as well as for the incidence of clinical complications like hepatic encephalopathy, acute kidney injury and mortality. RESULTS: Cumulative spontaneous bacterial peritonitis incidence did neither differ between the proton pump inhibitors and the no-proton pump inhibitors group nor between those taking the high (>40 mg/d) and the low (10-40 mg/d) proton pump inhibitors' dose. However, proton pump inhibitors' intake was associated with an impaired clinical course of spontaneous bacterial peritonitis reflected by a higher likelihood for acute kidney injury (71% vs 43%; P = .002), severe hepatic encephalopathy (15% vs 0%; P = .04) and an increased mortality (24% vs 0%; P = .008) within 28 days after spontaneous bacterial peritonitis diagnosis. In particular, patients with proton pump inhibitors dosages >40 mg/d had an increased short-term risk for acute kidney injury (adjusted hazard ratio: 1.86; P = .009) and mortality (adjusted hazard ratio: 2.05; P = .02). In contrast, there was no effect of proton pump inhibitors on acute kidney injury, hepatic encephalopathy and mortality in patients without spontaneous bacterial peritonitis irrespective of the applied proton pump inhibitors dosage. CONCLUSIONS: High dosages of proton pump inhibitors are associated with an adverse outcome in patients with spontaneous bacterial peritonitis. Thus, indication for high-dosage proton pump inhibitors therapy should be evaluated carefully in these patients.