Assessing the Burden of Abnormal LFTs and the Role of the Electronic Health Record: A Retrospective Study

Liver function tests in patients with hypertension in primary care: a prospective cohort study

BACKGROUND

Liver function tests (LFTs) are frequently used to monitor patients with hypertension in UK primary care. Evidence is lacking on whether testing improves outcomes.

AIM

To estimate the diagnostic accuracy of LFTs in patients with hypertension and determine downstream consequences of testing.

DESIGN & SETTING

Prospective study using the Clinical Practice Research Datalink (CPRD).

METHOD

In total, 30 000 patients with hypertension who had LFTs in 2015 were randomly selected from CPRD. The diagnostic accuracy measures for eight LFT analytes and an overall LFT panel were calculated against the reference standard of liver disease. Rates of consultations, blood tests, and referrals within 6 months following testing were measured.

RESULTS

The 1-year incidence of liver disease in patients with hypertension was 0.5% (95% confidence interval [CI] = 0.4% to 0.6%). Sensitivity and specificity of an LFT panel were modest: 61.3% (95% CI = 53.1% to 69.0%) and 73.8% (95% CI = 73.1% to 74.3%), respectively. The positive predictive value (PPV) of the eight individual LFT analytes were low ranging from 0.2% to 8.9%. Among patients who did not develop liver disease, mean number of consultations, referrals, and tests were higher in the 6 months following false-positives at 10.5, 0.7 and 29.8, respectively, compared with true-negatives: 8.6, 0.6, and 19.8.

CONCLUSION

PPVs of LFTs in primary care were low, with high rates of false-positive results and increased rates of subsequent consultations, referrals, and blood testing. Avoiding LFTs for routine monitoring could potentially reduce patients' anxiety, GP workload, and healthcare costs.

Approach to Elevated Liver Enzymes

Abnormal liver tests are one of the most common challenges in the primary care setting. Primary care practitioners order these tests for numerous reasons, including investigating abdominal signs and symptoms or suspected alcohol-use disorder, or to determine medication adverse effects. Evaluation should be guided by both the clinical presentation and the pattern of injury. In this article, we will focus on the epidemiology, pathophysiology, clinical presentation, diagnostic work-up, and management of elevated liver enzymes, with an emphasis on the most common causes of abnormal liver testing.

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.

Undiagnosed abnormal alanine transaminase levels in vulnerable populations: Impact of sex, race/ethnicity, and body mass

Background

Liver disease is a leading cause of death in the United States and is often initially detected incidentally on lab tests ordered by general practitioners. Alanine transaminase (ALT), a marker of liver inflammation, is commonly ordered and may be abnormal in the setting of elevated body mass index, diabetes and dyslipidemia. Data regarding ALT testing within vulnerable populations are limited. Therefore, the prevalence of ALT testing and abnormal ALT in the absence of known chronic liver disease (CLD) among a safety-net population were assessed and factors associated with these outcomes were identified.

Methods

In this retrospective longitudinal study of 92,997 patients seen between 01/2017-01/2019 within San Francisco's Safety-Net Healthcare System, electronic medical records were used to abstract data back to 04/1997. Descriptive analyses and multivariable modeling were performed.

Results

Overall, 59,323 (69%) without known CLD received an ALT test. Age, Black race, Latinx ethnicity, and metabolic factors were associated with higher odds of ALT testing, (p < 0.01). Among those with an abnormal ALT (44%) without known CLD: median age 53 years, 41% male, 19% White, 11% Black, 40% Latinx, 29% Asian/Pacific Islander (API), and 84% overweight/obese. On multivariable analysis, female sex (OR 2.7), Latinx ethnicity (OR 2.6), API race (OR 1.3), overweight/obesity (OR 1.8, OR 2.6), and dyslipidemia (OR 1.3) were associated with abnormal ALT, (p ≤ 0.001).

Conclusions

In the absence of known CLD, women, Latinx, API and persons with excess body weight were associated with greater odds of abnormal ALT. Future longitudinal studies are needed to confirm these differences and to determine if adequate work up for CLD is performed for abnormal ALT levels among at-risk populations.

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.

The Association of Abnormal Liver Tests with Hepatitis C Testing in Primary Care

BACKGROUND

As hepatitis C virus birth cohort (1945-1965) screening in primary care improves, testing patterns in response to persistently abnormal liver tests are less well known.

METHODS

This retrospective cohort study of a patient-centered medical home between 2007 and 2016 evaluates the association of abnormal liver chemistries and other clinical and demographic factors with hepatitis C antibody (HCV Ab) testing in patients with persistently abnormal liver tests. Patients with at least 2 consecutive abnormal liver tests were categorized by the clinical pattern of liver chemistry abnormality, including cholestatic, hepatocellular, and mixed patterns. The primary outcomes were: 1) completed HCV Ab tests; and 2) positive HCV Ab results for those patients tested.

RESULTS

Of 4512 patients with consecutive abnormal liver tests, only 730 (16%) underwent HCV Ab testing within 1 year of the second abnormality; 81/730 (11%) had HCV Ab detected. A logistic regression model revealed that mixed (odds ratio [OR] 2.20; 95% confidence interval [CI], 1.72-2.82) and hepatocellular (OR 1.43; 95% CI, 1.15-1.79) patterns of liver test abnormality, female sex, and alcohol and tobacco abuse were associated with higher odds of HCV Ab testing. Hepatocellular (OR 7.51; 95% CI, 2.18-25.94) and mixed patterns (OR 5.88; 95% CI, 1.64-21.15) of liver test abnormalities, male sex, Medicaid enrollment, and drug and tobacco abuse had higher odds of positive HCV Ab results.

CONCLUSIONS

There is opportunity to improve hepatitis C diagnostic testing in patients with consecutively elevated liver tests, and hepatocellular and mixed patterns of abnormality should prompt primary care providers to action.

When Do Clinicians Follow-up Abnormal Liver Tests in Primary Care?

BACKGROUND

Many guidelines addressing the approach to abnormal liver chemistries, including bilirubin, transaminases and alkaline phosphatase, recommend repeating the tests. However, when clinicians repeat testing is unknown.

MATERIAL AND METHODS

This retrospective study followed adult patients with abnormal liver chemistries in a patient-centered medical home (PCMH) from 2007 to 2016. All PCMH patients possessing at least 1 abnormal liver test (total bilirubin, aminotransferases and alkaline phosphatase) were included. Patients were followed from the index abnormal liver chemistry until the next liver test result, or the end of the study period. The primary predictor variable of interest was the number of abnormal chemistries (out of 4) on index testing. Demographic and clinical variables served as other potential predictors of outcome. A Cox proportional hazards model was applied to investigate associations between the predictor variables and the time to repeat liver chemistry testing.

RESULTS

Of 9,545 patients with at least 2 PCMH visits and 1 liver test abnormality, 6,489 (68%) obtained repeat testing within 1 year, and 80% of patients had follow-up tests within 2 years. Patients with multiple abnormal liver tests and those with higher degrees of abnormality were associated with shorter time to repeat testing.

CONCLUSIONS

A large proportion of patients with abnormal liver tests still lack repeat testing at 1 year. The number of liver abnormal liver tests and degree of elevation were inversely associated with the time to repeat testing.