FIB-4 as a Time-varying Covariate and Its Association With Severe Liver Disease in Primary Care: A Time-dependent Cox Regression Analysis.

BACKGROUND AND GOALS: The Fibrosis-4 Index (FIB-4) has demonstrated a strong association with severe liver disease (SLD) outcomes in primary care, but previous studies have only evaluated this relationship using 1 or 2 FIB-4 scores. In this study, we determined the association of FIB-4 as a time-varying covariate with SLD risk using time-dependent Cox regression models. STUDY: This retrospective cohort study included primary care patients with at least 2 FIB-4 scores between 2012 and 2021. The outcome was the occurrence of an SLD event, a composite of cirrhosis, complications of cirrhosis, hepatocellular carcinoma, and liver transplantation. The primary predictor was FIB-4 advanced fibrosis risk, categorized as low-(<1.3), indeterminate-(1.3≤FIB to 4<2.67), and high-risk (≥2.67). FIB-4 scores were calculated and the index, last, and maximum FIB-4s were identified. Time-dependent Cox regression models were used to estimate hazard ratios (HR) and their corresponding 95% CI with adjustment for potentially confounding covariates. RESULTS: In the cohort, 20,828 patients had a median of 5 (IQR: 3 to 11) FIB-4 scores each and 3% (n=667) suffered an SLD outcome during follow-up. Maximum FIB-4 scores were indeterminate-risk for 34% (7149) and high-risk for 24% (4971) of the sample, and 32% (6692) of patients had an increase in fibrosis risk category compared with their index value. The adjusted Cox regression model demonstrated an association between indeterminate- (hazard ratio 3.21; 95% CI 2.33-4.42) and high-risk (hazard ratio 20.36; 95% CI 15.03-27.57) FIB-4 scores with SLD outcomes. CONCLUSIONS: Multiple FIB-4 values per patient are accessible in primary care, FIB-4 fibrosis risk assessments change over time, and high-risk FIB-4 scores (≥2.67) are strongly associated with severe liver disease outcomes when accounting for FIB-4 as a time-varying variable.

Indeterminate etiology of acute liver failure in North America: Less common, still grave prognosis.

BACKGROUND: The etiology of acute liver failure (ALF) remains one of the most important factors in determining prognosis and predicting outcomes. In a significant proportion of ALF cases, however, the etiology remains unknown and is categorized as indeterminate ALF (IND-ALF). In this study, we summarize findings from patients with IND-ALF from 32 transplant centers across the United States, and we compare laboratory, prognostic, and outcome data for patients with IND-ALF. METHODS: Between 1998 and 2019, 3364 adult patients with ALF or acute liver injury (ALI) from 32 liver transplant centers were enrolled in the ALFSG registry. The primary clinical outcome of interest was 21-day transplant-free survival (TFS). RESULTS: Of the 3364 patients enrolled in the ALFSG registry, 3.4 % (n = 114) were adjudicated as true indeterminate. On multivariate analysis, patients with a lower bilirubin, lower INR, lack of use of mechanical ventilation and no clinical features of coma at baseline had a higher odds ratio of transplant free survival. The number of deaths were similar between patients with true-IND ALF versus patients with indeterminable ALF (29.8% vs. 27.2%), with almost half of the patients requiring liver transplant (42.1% vs. 45.7%). CONCLUSION: We illustrate the poor prognoses that true-IND-ALF and indeterminable ALF carry and the need for emergency liver transplantation in most cases.

Autoimmune hepatitis presenting as acute liver failure: A 20-year retrospective review of North America.

Autoimmune hepatitis is a common cause of acute liver failure. Treatment includes steroids for acute liver injury and liver transplantation in those who fail to respond or develop acute liver failure. The aim of this study is to further characterize acute liver failure secondary to autoimmune hepatitis and identify variables that predict 21-day transplant-free survival. This study included adults hospitalized with acute liver failure enrolled in the Acute Liver Failure Study Group Registry between 1998 and 2019 from 32 centers within the US. The etiology of all cases was reviewed by the Adjudication Committee, and all cases identified as autoimmune hepatitis were included. Acute liver injury was defined as an INR ≥2.0 without encephalopathy and acute liver failure as INR ≥ 1.5 with encephalopathy. Laboratory and clinical data were reviewed. Variables significantly associated with 21-day transplant-free survival were used to develop a multivariable logistic regression model.  A total of 193 cases of acute liver failure secondary to autoimmune hepatitis were identified and reviewed. There were 161 patients (83.4%) diagnosed with acute liver failure on enrollment, and 32 (16.6%) developed acute liver failure during hospitalization. At 21 days, 115 (59.6%) underwent liver transplantation, 28 (14.5%) had transplant-free survival, and 46 (23.8%) died before liver transplantation. Higher admission values of bilirubin, INR, and coma grade were associated with worse outcomes. A prognostic index incorporating bilirubin, INR, coma grade, and platelet count had a concordance statistic of 0.84. Acute liver failure secondary to autoimmune hepatitis is associated with a high short-term mortality. We developed a model specifically for autoimmune hepatitis that may be helpful in predicting 21-day transplant-free survival and early identification of patients in need of expedited liver transplant evaluation.

Real-World Primary Care Data Comparing ALT and FIB-4 in Predicting Future Severe Liver Disease Outcomes.

BACKGROUND: Alanine aminotransferase (ALT) has long provided a cue for chronic liver disease (CLD) diagnostic evaluation, but the Fibrosis-4 Index (FIB-4), a serologic score used for predicting advanced fibrosis risk in CLD, may provide an alternative signal. OBJECTIVE: Compare the predictive performance of FIB-4 with ALT for severe liver disease (SLD) events while adjusting for potential confounders. DESIGN: Retrospective cohort study of primary care electronic health record data from 2012 to 2021. PATIENTS: Adult primary care patients with at least two sets of ALT and other lab values necessary for calculating two unique FIB-4 scores, excluding those patients with an SLD prior to their index FIB-4 value. MAIN MEASURES: The occurrence of an SLD event, a composite of cirrhosis, hepatocellular carcinoma, and liver transplantation, was the outcome of interest. Categories of ALT elevation and FIB-4 advanced fibrosis risk were the primary predictor variables. Multivariable logistic regression models were developed to evaluate the association of FIB-4 and ALT with SLD, and the areas under the curve (AUC) for each model were compared. KEY RESULTS: The cohort of 20,828 patients included 14% with an abnormal index ALT (≥40 IU/L) and 8% with a high-risk index FIB-4 (≥2.67). During the study period, 667 (3%) patients suffered an SLD event. Adjusted multivariable logistic regression models demonstrated an association between high-risk FIB-4 (OR 19.34; 95%CI 15.50-24.13), persistently high-risk FIB-4 (OR 23.85; 95%CI 18.24-31.17), abnormal ALT (OR 7.07; 95%CI 5.81-8.59), and persistently abnormal ALT (OR 7.58; 95%CI 5.97-9.62) with SLD outcomes. The AUC of the index FIB-4 (0.847, p < 0.001) and combined FIB-4 (0.849, p < 0.001) adjusted models exceeded the index ALT adjusted model (0.815). CONCLUSIONS: High-risk FIB-4 scores demonstrated superior performance compared to abnormal ALT in predicting future SLD outcomes.

Identifying Patients at Risk for Fibrosis in a Primary Care NAFLD Cohort.

GOALS AND BACKGROUND: Using natural language processing to create a nonalcoholic fatty liver disease (NAFLD) cohort in primary care, we assessed advanced fibrosis risk with the Fibrosis-4 Index (FIB-4) and NAFLD Fibrosis Score (NFS) and evaluated risk score agreement. MATERIALS AND METHODS: In this retrospective study of adults with radiographic evidence of hepatic steatosis, we calculated patient-level FIB-4 and NFS scores and categorized them by fibrosis risk. Risk category and risk score agreement was analyzed using weighted κ, Pearson correlation, and Bland-Altman analysis. A multinomial logistic regression model evaluated associations between clinical variables and discrepant FIB-4 and NFS results. RESULTS: Of the 767 patient cohorts, 71% had a FIB-4 or NFS score in the indeterminate-risk or high-risk category for fibrosis. Risk categories disagreed in 43%, and scores would have resulted in different clinical decisions in 30% of the sample. The weighted κ statistic for risk category agreement was 0.41 [95% confidence interval (CI): 0.36-0.46] and the Pearson correlation coefficient for log FIB-4 and NFS was 0.66 (95% CI: 0.62-0.70). The multinomial logistic regression analysis identified black race (odds ratio=2.64, 95% CI: 1.84-3.78) and hemoglobin A1c (odds ratio=1.37, 95% CI: 1.23-1.52) with higher odds of having an NFS risk category exceeding FIB-4. CONCLUSIONS: In a primary care NAFLD cohort, many patients had elevated FIB-4 and NFS risk scores and these risk categories were often in disagreement. The choice between FIB-4 and NFS for fibrosis risk assessment can impact clinical decision-making and may contribute to disparities of care.

FIB-4 and incident severe liver outcomes in patients with undiagnosed chronic liver disease: A Fine-Gray competing risk analysis.

BACKGROUND AND AIMS: The Fibrosis-4 index (FIB-4) can reliably assess fibrosis risk in patients with chronic liver disease, and advanced fibrosis is associated with severe liver disease (SLD) outcomes. However, CLD is underdiagnosed in primary care. We examined the association between FIB-4 risk strata and the incidence of SLD preceding a CLD diagnosis while considering incident CLD diagnoses as competing risks. METHODS: Using primary care clinic data between 2007 and 2018, we identified patients with two FIB-4 scores and no liver disease diagnoses preceding the index FIB-4. Patients were followed from index FIB-4 until an incident SLD (a composite of cirrhosis, hepatocellular carcinoma or liver transplantation), CLD or were censored. Hazard ratios were computed using a Fine-Gray competing risk model. RESULTS: Of 20 556 patients, there were 54.8% in the low, 34.8% in the indeterminate, 6.6% in the high and 3.8% in the persistently high-risk FIB-4 strata. During a mean 8.2 years of follow-up, 837 (4.1%) patients experienced an SLD outcome and 11.5% of the sample received a CLD diagnosis. Of patients with an SLD event, 49% received no preceding CLD diagnosis. In the adjusted Fine-Gray model, the indeterminate (HR 1.41, 95% CI 1.17-1.71), high (HR 4.65, 95% CI 3.76-5.76) and persistently high-risk (HR 7.60, 95% CI 6.04-9.57) FIB-4 risk strata were associated with a higher incidence of SLD compared to the low-risk stratum. CONCLUSIONS: FIB-4 scores with indeterminate- and high-risk values are associated with an increased incidence of SLD in primary care patients without known CLD.

The Association of Fibrosis-4 Index Scores with Severe Liver Outcomes in Primary Care.

BACKGROUND: The Fibrosis-4 Index (FIB-4)non-invasively assesses fibrosis risk in chronic liver disease (CLD), but underdiagnosis limits FIB-4's application in primary care. OBJECTIVE: To evaluate the association of FIB-4 risk with hazard of severe liver outcomes in primary care patients with and without diagnosed CLD. DESIGN: Retrospective cohort study of primary care data from 2007 to 2018. PARTICIPANTS: Adult patients with qualifying aminotransferase and platelet count results were included and a single FIB-4 score was calculated for each patient using the first of these values. Patients with a CLD diagnosis or outcome prior to their FIB-4 score were excluded. MEASURES: FIB-4 advanced fibrosis risk categorization (low, indeterminate, and high) was the primary predictor variable. Patients were followed from FIB-4 score to a severe liver outcome, a composite of cirrhosis, liver transplantation, and hepatocellular carcinoma. We analyzed the association of FIB-4 risk categories with hazard risk of a severe liver outcome using stratified Cox regression models, stratifying patients by known CLD. KEY RESULTS: A total of 20,556 patients were followed for a mean 2,978 days (SD 1,201 days), and 4% of patients experienced a severe liver outcome. Of patients with low-, indeterminate-, and high-risk FIB-4 scores, 2%, 4%, and 20% suffered a severe liver outcome, respectively. In the overall adjusted model, high-risk FIB-4 scores were associated with hazard of severe liver disease (HR 6.64; 95% CI 5.58-7.90). High-risk FIB-4 scores were associated with severe liver outcomes for patients with known NAFLD (HR 7.32; 95% CI 3.44-15.58), other liver disease (HR 11.39; 95% CI 8.53-15.20), and no known CLD (HR 4.05; 95% CI 3.10-5.28). CONCLUSIONS: High-risk FIB-4 scores were strongly associated with risk of severe liver outcomes in patients with and without known CLD. Comprehensive FIB-4 application in primary care may signal silently advancing liver fibrosis.

Advanced liver fibrosis and the metabolic syndrome in a primary care setting.

AIMS: The fibrosis-4 index (FIB-4) and NAFLD fibrosis score (NFS) are noninvasive and accessible methods for assessing advanced liver fibrosis risk in primary care. We evaluated the distribution of FIB-4 and NFS scores in primary care patients with clinical signals for nonalcoholic fatty liver disease (NAFLD). MATERIALS AND METHODS: This retrospective cohort study of electronic record data between 2007 and 2018 included adults with at least one abnormal aminotransferase and no known (non-NAFLD) liver disease. We calculated patient-level FIB-4 and NFS scores, the proportion of patients with mean values exceeding advanced fibrosis thresholds (indeterminate risk: FIB-4 > 1.3, NFS > -1.455; high-risk: FIB-4 > 2.67, NFS > 0.676), and the proportion of patients with a NAFLD International Classification of Diseases-9/10 code. Logistic regression models evaluated the associations of metabolic syndrome (MetS) components with elevated FIB-4 and NFS scores. RESULTS: The cohort included 6506 patients with a median of 6 (interquartile range: 3-13) FIB-4 and NFS scores per patient. Of these patients, 81% had at least two components of MetS, 29% had mean FIB-4 and NFS scores for indeterminate fibrosis risk, and 11% had either mean FIB-4 or NFS scores exceeding the high advanced fibrosis risk thresholds. Regression models identified associations of low high-density lipoprotein, hyperglycemia, Black race and male gender with high-risk FIB-4 and NFS values. Only 5% of patients had existing diagnoses for NAFLD identified. CONCLUSIONS: Many primary care patients have FIB-4 and NFS scores concerning for advanced fibrosis, but rarely a diagnosis of NAFLD. Elevated FIB-4 and NFS scores may provide signals for further clinical evaluation of liver disease in primary care settings.