Noninvasive tests for liver fibrosis in 2024: are there different scales for different diseases?

Liver fibrosis is the common pathway from various chronic liver diseases and its progression leads to cirrhosis which carries a significant risk for the development of portal hypertension-related complications and hepatocellular carcinoma. It is crucial to identify and halt the worsening of liver fibrosis given its important prognostic implication. Liver biopsy is the gold standard for assessing the degree of liver fibrosis but is limited due to its invasiveness and impracticality for serial monitoring. Many noninvasive tests have been developed over the years trying to assess liver fibrosis in a practical and accurate way. The tests are mainly laboratory- or imaging-based, or in combination. Laboratory-based tests can be derived from simply routine blood tests to patented laboratory parameters. Imaging modalities include ultrasound and magnetic resonance elastography, in which vibration-controlled transient elastography is the most widely validated and adopted whereas magnetic resonance elastography has been proven the most accurate liver fibrosis assessment tool. Nonetheless, noninvasive tests do not always apply to all liver diseases, nor does a common cut-off value of a test mean the same degree of liver fibrosis in different scenarios. In this review, we discuss the diagnostic and prognostic performance, as well as the confounders and limitations, of different noninvasive tests on liver fibrosis assessment in various liver diseases.

Limited Sustained Remission After Nucleos(t)ide Analog Withdrawal: Results From a Large, Global, Multiethnic Cohort of Patients With Chronic Hepatitis B (RETRACT-B Study).

INTRODUCTION: Complete viral suppression with nucleos(t)ide analogs (NAs) has led to a profound reduction in hepatocellular carcinoma and mortality among patients with chronic hepatitis B. Finite therapy yields higher rates of functional cure; however, initial hepatitis B virus (HBV) DNA and alanine aminotransferase (ALT) elevations are almost certain after treatment interruption. We aimed to analyze off-treatment outcomes beyond 12 months after NA cessation. METHODS: Patients with well-suppressed chronic hepatitis B who were hepatitis B e antigen-negative at NA cessation and remained off treatment without hepatitis B surface antigen (HBsAg) loss at 12 months were included (n = 945). HBV DNA and ALT fluctuations were allowed within the first 12 months. We used Kaplan-Meier methods to analyze outcomes beyond 12 months. Sustained remission was defined as HBV DNA <2,000 IU/mL and ALT <2× upper limit of normal (ULN) and an ALT flare as ALT ≥5× ULN. RESULTS: Cumulative probability of sustained remission was 29.7%, virological relapse was 65.2% with a mean peak HBV DNA of 5.0 ± 1.5 log 10 IU/mL, an ALT flare was 15.6% with a median peak ALT × ULN of 8.3 (5.7-11.3), HBsAg loss was 9.9% and retreatment was 34.9% at 48 months after NA cessation. A single occurrence of virological relapse or an ALT flare within the first 12 months off-treatment were associated with significantly lower rates of sustained remission beyond 12 months. DISCUSSION: Despite allowing for HBV DNA and ALT fluctuations within the first 12 months off-treatment, most patients without HBsAg loss did not maintain a sustained response thereafter. The best candidates for NA withdrawal are patients with low HBsAg levels at NA cessation, and those without profound or recurrent virological and biochemical relapses in the first off-treatment year.

Serum PRO-C3 is useful for risk prediction and fibrosis assessment in MAFLD with chronic kidney disease in an Asian cohort.

BACKGROUND: Metabolic dysfunction-associated fatty liver disease (MAFLD) is an emerging risk factor for chronic kidney disease (CKD). N-terminal propeptide of collagen type 3 (PRO-C3) is a biomarker of advanced fibrosis in MAFLD and PRO-C3 may be involved in renal fibrosis. We aimed to use PRO-C3 measurements to generate a new algorithmic score to test the prediction of MAFLD with chronic kidney disease (MAFLD-CKD). METHODS: A derivation and independent validation cohort of 750 and 129 Asian patients with biopsy-confirmed MAFLD were included. Serum PRO-C3 concentration was measured and regression analyses were performed to examine associations with MAFLD-CKD. A derivative algorithm for MAFLD-CKD risk prediction was evaluated with receiver operator characteristic (ROC) curve analysis. RESULTS: The study included two Asian cohorts (n = 180 with MAFLD-CKD; mean-eGFR: 94.93 mL/min/1.73 m2; median-urinary albumin-to-creatinine ratio: 6.58 mg/mmol). PRO-C3 was associated with the severity of MAFLD-CKD and independently associated with MAFLD-CKD (adjusted odds ratio = 1.16, 95% confidence interval [CI]: 1.08-1.23, p < .001). A new non-invasive score (termed PERIOD) including PRO-C3 efficiently predicted MAFLD-CKD (AUROC = .842, 95% CI: .805-.875). Accuracy, specificity and negative predictive values were 80.2%, 85.1% and 88.4%, respectively. In the validation cohort, the PERIOD score had good diagnostic performance (AUROC = .807, 95% CI: .691-.893) with similar results in all patient subgroups. In the MAFLD-CKD subgroup, the accuracy for identifying advanced fibrosis was further improved by combining the PRO-C3-based ADAPT with the Agile 3+ scores (AUROC = .90, 95% CI: .836-.964). CONCLUSIONS: The PERIOD score is helpful for accurately predicting the risk of MAFLD-CKD. PRO-C3 can also be used to assess liver fibrosis in people with MAFLD-CKD.

Chronic hepatitis B baseline viral load and on-treatment liver cancer risk: A multinational cohort study of HBeAg-positive patients.

BACKGROUND AND AIMS: A single-nation study reported that pretreatment HBV viral load is associated with on-treatment risk of HCC in patients who are HBeAg-positive without cirrhosis and with chronic hepatitis B initiating antiviral treatment. We aimed to validate the association between baseline HBV viral load and on-treatment HCC risk in a larger, multinational cohort. APPROACH AND RESULTS: Using a multinational cohort from Korea, Hong Kong, and Taiwan involving 7545 adult patients with HBeAg-positive, without cirrhosis and with chronic hepatitis B who started entecavir or tenofovir treatment with baseline HBV viral load ≥5.00 log 10 IU/mL, HCC risk was estimated by baseline viral load. HBV viral load was analyzed as a categorical variable. During continuous antiviral treatment (median, 4.28 y), HCC developed in 200 patients (incidence rate, 0.61 per 100 person-years). Baseline HBV DNA level was independently associated with on-treatment HCC risk in a nonlinear pattern. HCC risk was lowest with the highest baseline viral load (≥8.00 log 10 IU/mL; incidence rate, 0.10 per 100 person-years), but increased sharply as baseline viral load decreased. The adjusted HCC risk was 8.05 times higher (95% CI, 3.34-19.35) with baseline viral load ≥6.00 and <7.00 log 10 IU/mL (incidence rate, 1.38 per 100 person-years) compared with high (≥8.00 log 10 IU/mL) baseline viral load ( p <0.001). CONCLUSIONS: In a multinational cohort of adult patients with HBeAg-positive without cirrhosis and with chronic hepatitis B, baseline HBV viral load was significantly associated with HCC risk despite antiviral treatment. Patients with the highest viral load who initiated treatment had the lowest long-term risk of HCC development.

CAMP-B score predicts the risk of hepatocellular carcinoma in patients with chronic hepatitis B after HBsAg seroclearance.

BACKGROUND: Risk of hepatocellular carcinoma (HCC) persists after hepatitis B surface antigen (HBsAg) seroclearance in patients with chronic hepatitis B (CHB). AIMS: To identify risk factors and construct a predictive model for HCC development. METHODS: We retrospectively analysed patients with CHB with HBsAg seroclearance. Primary outcome was HCC development. Factors identified from a multivariate Cox model in the training cohort, consisting of 3476 patients from two Korean hospitals, were used to construct the prediction model. External validation was performed using data from 5255 patients in Hong Kong. RESULTS: In the training cohort, HCC occurred in 102 patients during 24,019 person-years of observation (0.43%/year). Risk scores were assigned to cirrhosis (C:3), age ≥50 years (A:2), male sex (M:3) and platelet count <150,000/mm3 (P:1); all were independently associated with an increased risk of HCC in multivariate analysis The time-dependent area under receiver operating characteristic curves for 5, 10 and 15 years in the training and validation cohorts were 0.782, 0.817 and 0.825 and 0.785, 0.771 and 0.796, respectively. In the validation cohort, 85 patients developed HCC (0.24%/year). The corresponding incidence of HCC in the low-, intermediate- and high-risk groups were 0.07%, 0.37% and 0.90%, respectively. CONCLUSIONS: The CAMP-B score (cirrhosis, age ≥50 years, male sex and platelet count <150,000/mm3/L) was significantly associated with HCC development after HBsAg seroclearance. CAMP-B score can be easily implemented in real-world clinical practice and helps stratify HCC risk in patients with CHB following HBsAg seroclearance.

Vibration-Controlled Transient Elastography Scores to Predict Liver-Related Events in Steatotic Liver Disease.

Importance: Metabolic dysfunction-associated steatotic liver disease (MASLD) is currently the most common chronic liver disease worldwide. It is important to develop noninvasive tests to assess the disease severity and prognosis. Objective: To study the prognostic implications of baseline levels and dynamic changes of the vibration-controlled transient elastography (VCTE)-based scores developed for the diagnosis of advanced fibrosis (Agile 3+) and cirrhosis (Agile 4) in patients with MASLD. Design, Setting, and Participants: This cohort study included data from a natural history cohort of patients with MASLD who underwent VCTE examination at 16 tertiary referral centers in the US, Europe, and Asia from February 2004 to January 2023, of which the data were collected prospectively at 14 centers. Eligible patients were adults aged at least 18 years with hepatic steatosis diagnosed by histologic methods (steatosis in ≥5% of hepatocytes) or imaging studies (ultrasonography, computed tomography or magnetic resonance imaging, or controlled attenuation parameter ≥248 dB/m by VCTE). Main Outcomes and Measures: The primary outcome was liver-related events (LREs), defined as hepatocellular carcinoma or hepatic decompensation (ascites, variceal hemorrhage, hepatic encephalopathy, or hepatorenal syndrome), liver transplant, and liver-related deaths. The Agile scores were compared with histologic and 8 other noninvasive tests. Results: A total of 16 603 patients underwent VCTE examination at baseline (mean [SD] age, 52.5 [13.7] years; 9600 [57.8%] were male). At a median follow-up of 51.7 (IQR, 25.2-85.2) months, 316 patients (1.9%) developed LREs. Both Agile 3+ and Agile 4 scores classified fewer patients between the low and high cutoffs than most fibrosis scores and achieved the highest discriminatory power in predicting LREs (integrated area under the time-dependent receiver-operating characteristic curve, 0.89). A total of 10 920 patients (65.8%) had repeated VCTE examination at a median interval of 15 (IQR, 11.3-27.7) months and were included in the serial analysis. A total of 81.9% of patients (7208 of 8810) had stable Agile 3+ scores and 92.6% of patients (8163 of 8810) had stable Agile 4 scores (same risk categories at both assessments). The incidence of LREs was 0.6 per 1000 person-years in patients with persistently low Agile 3+ scores and 30.1 per 1000 person-years in patients with persistently high Agile 3+ scores. In patients with high Agile 3+ score at baseline, a decrease in the score by more than 20% was associated with substantial reduction in the risk of LREs. A similar trend was observed for the Agile 4 score, although it missed more LREs in the low-risk group. Conclusions and Relevance: Findings of this study suggest that single or serial Agile scores are highly accurate in predicting LREs in patients with MASLD, making them suitable alternatives to liver biopsy in routine clinical practice and in phase 2b and 3 clinical trials for steatohepatitis.

Genomic origin, fragmentomics, and transcriptional properties of long cell-free DNA molecules in human plasma.

Recent studies have revealed an unexplored population of long cell-free DNA (cfDNA) molecules in human plasma using long-read sequencing technologies. However, the biological properties of long cfDNA molecules (>500 bp) remain largely unknown. To this end, we have investigated the origins of long cfDNA molecules from different genomic elements. Analysis of plasma cfDNA using long-read sequencing reveals an uneven distribution of long molecules from across the genome. Long cfDNA molecules show overrepresentation in euchromatic regions of the genome, in sharp contrast to short DNA molecules. We observe a stronger relationship between the abundance of long molecules and mRNA gene expression levels, compared with short molecules (Pearson's r = 0.71 vs. -0.14). Moreover, long and short molecules show distinct fragmentation patterns surrounding CpG sites. Leveraging the cleavage preferences surrounding CpG sites, the combined cleavage ratios of long and short molecules can differentiate patients with hepatocellular carcinoma (HCC) from non-HCC subjects (AUC = 0.87). We also investigated knockout mice in which selected nuclease genes had been inactivated in comparison with wild-type mice. The proportion of long molecules originating from transcription start sites are lower in Dffb-deficient mice but higher in Dnase1l3-deficient mice compared with that of wild-type mice. This work thus provides new insights into the biological properties and potential clinical applications of long cfDNA molecules.

Reply to Allaire, M.; Thabut, D. Comment on "Wu et al. Baveno VII Criteria Is an Accurate Risk Stratification Tool to Predict High-Risk Varices Requiring Intervention and Hepatic Events in Patients with Advanced Hepatocellular Carcinoma. Cancers 2023, 15, 2480".

We thank Allaire et al [...].

Performance of continuous controlled attenuation parameter and liver stiffness measurement by the novel SmartExam in metabolic dysfunction-associated steatotic liver disease.

BACKGROUND & AIMS: FibroScan® Expert 630 and FibroScan® Mini+430 are novel vibration-controlled transient elastography devices equipped with the same SmartExam software, which allows continuous measurement of controlled attenuation parameter (CAP) during the entire examination. This study aims to compare the CAP variabilities and the quantification for liver fibrosis and steatosis between the conventional FibroScan and the SmartExam-equipped machines in patients with metabolic dysfunction-associated steatotic liver disease (MASLD). METHODS: This retrospective study included 118 patients with biopsy-proven MASLD who underwent liver biopsy at two tertiary centres between 2021 and 2023. Liver stiffness and steatosis measurements were performed using both FibroScan machines and M and XL probes for each individual. Liver histology was used as the reference standard for liver fibrosis and steatosis staging. RESULTS: Standard deviations of continuous CAP (cCAP) were significantly lower than those of CAP for all probes (p < .0001). CAP variability was significantly associated with body mass index (p < .01), probe selection (p < .001) as well as the random effect of centre. Only the effect of probe selection (p < .001) was significantly associated with cCAP variability. No significant difference was found in the performance of staging liver fibrosis and steatosis between two types of machines at the same cut-offs. CONCLUSIONS: The SmartExam-based VCTE reduces the variability of CAP measurement and achieves a similar accuracy as the FibroScan 502 device for the estimation of both hepatic steatosis and fibrosis. Future studies should determine if cCAP is a better tool to monitor changes in steatosis than the original CAP.

Machine learning improves the prediction of significant fibrosis in Asian patients with metabolic dysfunction-associated steatotic liver disease - The Gut and Obesity in Asia (GO-ASIA) Study.

BACKGROUND: The precise estimation of cases with significant fibrosis (SF) is an unmet goal in non-alcoholic fatty liver disease (NAFLD/MASLD). AIMS: We evaluated the performance of machine learning (ML) and non-patented scores for ruling out SF among NAFLD/MASLD patients. METHODS: Twenty-one ML models were trained (N = 1153), tested (N = 283), and validated (N = 220) on clinical and biochemical parameters of histologically-proven NAFLD/MASLD patients (N = 1656) collected across 14 centres in 8 Asian countries. Their performance for detecting histological-SF (≥F2fibrosis) were evaluated with APRI, FIB4, NFS, BARD, and SAFE (NPV/F1-score as model-selection criteria). RESULTS: Patients aged 47 years (median), 54.6% males, 73.7% with metabolic syndrome, and 32.9% with histological-SF were included in the study. Patients with SFvs.no-SF had higher age, aminotransferases, fasting plasma glucose, metabolic syndrome, uncontrolled diabetes, and NAFLD activity score (p < 0.001, each). ML models showed 7%-12% better discrimination than FIB-4 to detect SF. Optimised random forest (RF) yielded best NPV/F1 in overall set (0.947/0.754), test set (0.798/0.588) and validation set (0.852/0.559), as compared to FIB4 in overall set (0.744/0.499), test set (0.722/0.456), and validation set (0.806/0.507). Compared to FIB-4, RF could pick 10 times more patients with SF, reduce unnecessary referrals by 28%, and prevent missed referrals by 78%. Age, AST, ALT fasting plasma glucose, and platelet count were top features determining the SF. Sequential use of SAFE < 140 and FIB4 < 1.2 (when SAFE > 140) was next best in ruling out SF (NPV of 0.757, 0.724 and 0.827 in overall, test and validation set). CONCLUSIONS: ML with clinical, anthropometric data and simple blood investigations perform better than FIB-4 for ruling out SF in biopsy-proven Asian NAFLD/MASLD patients.

Clinical Management of Gastrointestinal and Liver Toxicities of Immune Checkpoint Inhibitors.

Immune checkpoint inhibitors have transformed the treatment paradigm for various types of cancer. Nonetheless, with the utilization of these groundbreaking treatments, immune-related adverse events (irAEs) are increasingly encountered. Colonic and hepatic involvement are among the most frequently encountered irAEs. Drug-induced side effects, infectious causes, and tumor-related symptoms are the key differentials for irAE complications. Potential risk factors for the development of irAEs include combination use of immune checkpoint inhibitors, past development of irAEs with other immunotherapy treatments, certain concomitant drugs, and a pre-existing personal or family history of autoimmune illness such as inflammatory bowel disease. The importance of early recognition, timely and proper management cannot be understated, as there are profound clinical implications on the overall cancer treatment plan and prognosis once these adverse events occur. Herein, we cover the clinical management of the well-established gastrointestinal irAEs of enterocolitis and hepatitis, and also provide an overview of several other emerging entities.

Bacterial infections in patients with COVID-19: the impact of procalcitonin testing on antibiotics prescription in the real world.

BACKGROUND: Bacterial infections are not prevalent among patients hospitalized with COVID-19, while unnecessary prescription of antibiotics was commonly observed. This study aimed to determine the impact of procalcitonin testing on antibiotics prescription in the real-world setting. METHODS: We performed a territory-wide retrospective cohort study involving all laboratory-confirmed patients hospitalized in public hospitals in Hong Kong in 2020 with COVID-19. We determined the prevalence of bacterial co-infections (documented infections within 72 h of admission) and secondary bacterial infections (infections after 72 h of admission) and antibiotics consumption, and the correlation between procalcitonin testing and antibiotics prescription. RESULTS: The cohort included 8666 patients, with mean age 45.3 ± 19.9 years, 48.5% male, and comorbidities in 26.9%. Among 2688 patients with bacterial cultures performed, 147 (5.5%) had bacterial co-infections, and 222 (8.3%) had secondary bacterial infections. Antibiotics were prescribed for 2773 (32.0%) patients during the hospital admission. Procalcitonin tests were performed for 2543 (29.3%) patients. More patients with procalcitonin testing received antibiotics (65.9% vs. 17.9%, p < 0.001). Procalcitonin testing was associated with 5-fold increased risk of antibiotics prescription after adjusting for confounding variables. At hospital level, procalcitonin testing correlated with antibiotics prescription. Patients with procalcitonin level < 0.5 ng/mL had a lower probability of antibiotics initiation and shorter duration of antibiotics therapy. CONCLUSIONS: Procalcitonin testing was not associated with lower prescription of antibiotics. Patients with low procalcitonin level had lower antibiotics exposure, supporting the use of procalcitonin to exclude bacterial infections aiding early stopping of antibiotics among patients hospitalized with COVID-19.

Atherosclerotic cardiovascular disease risk profile of patients with chronic hepatitis B treated with tenofovir alafenamide or tenofovir disoproxil fumarate for 96 weeks.

BACKGROUND: Patients with chronic hepatitis B (CHB) who switch from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide (TAF) show changes in lipid profiles. AIM: To evaluate how these changes affect cardiovascular risk. METHODS: This pooled analysis, based on two large prospective studies, evaluated fasting lipid profiles of patients with CHB who were treated with TAF 25 mg/day or TDF 300 mg/day for 96 weeks. Patients who fulfilled the American College of Cardiology criteria (age 40-79 years, high-density lipoprotein [HDL] 20-100 mg/dL, total cholesterol [TC] 130-320 mg/dL and systolic blood pressure 90-200 mmHg) required to assess 10-year atherosclerotic cardiovascular disease (ASCVD) risk with baseline lipid data and at least one post-baseline measurement were included in the ASCVD-risk population. The 10-year ASCVD risk was calculated for patients in this population, and changes from baseline to Week 96 were assessed using intermediate- (≥7.5%) and high-risk (≥20%) cut-offs. RESULTS: Among 1632 patients, 620 (38%) met the criteria for the ASCVD-risk population. At Week 96, fasting levels of all lipids, except TC:HDL ratio, were lower with TDF than TAF. No significant increase was observed in overall ASCVD risk or in any ASCVD-risk categories during the 96-week treatment period compared with baseline. A similar proportion of patients in the TAF and TDF treatment groups (1.3% and 2.3%, respectively; p = 0.34) reported cardiovascular events. CONCLUSION: Despite on-treatment differences in lipid profiles with TAF and TDF, predicted cardiovascular risk and clinical events were similar for both groups after 96 weeks.

A Liver Stiffness-Based Etiology-Independent Machine Learning Algorithm to Predict Hepatocellular Carcinoma.

BACKGROUND & AIMS: The existing hepatocellular carcinoma (HCC) risk scores have modest accuracy, and most are specific to chronic hepatitis B infection. In this study, we developed and validated a liver stiffness-based machine learning algorithm (ML) for prediction and risk stratification of HCC in various chronic liver diseases (CLDs). METHODS: MLs were trained for prediction of HCC in 5155 adult patients with various CLDs in Korea and further tested in 2 prospective cohorts from Hong Kong (HK) (N = 2732) and Europe (N = 2384). Model performance was assessed according to Harrell's C-index and time-dependent receiver operating characteristic (ROC) curve. RESULTS: We developed the SMART-HCC score, a liver stiffness-based ML HCC risk score, with liver stiffness measurement ranked as the most important among 9 clinical features. The Harrell's C-index of the SMART-HCC score in HK and Europe validation cohorts were 0.89 (95% confidence interval, 0.85-0.92) and 0.91 (95% confidence interval, 0.87-0.95), respectively. The area under ROC curves of the SMART-HCC score for HCC in 5 years was ≥0.89 in both validation cohorts. The performance of SMART-HCC score was significantly better than existing HCC risk scores including aMAP score, Toronto HCC risk index, and 7 hepatitis B-related risk scores. Using dual cutoffs of 0.043 and 0.080, the annual HCC incidence was 0.09%-0.11% for low-risk group and 2.54%-4.64% for high-risk group in the HK and Europe validation cohorts. CONCLUSIONS: The SMART-HCC score is a useful machine learning-based tool for clinicians to stratify HCC risk in patients with CLDs.

Diagnostic and prognostic performance of the SAFE score in non-alcoholic fatty liver disease.

BACKGROUND & AIMS: The steatosis-associated fibrosis estimator (SAFE) score was developed to detect clinically significant liver fibrosis in patients with NAFLD in the United States. We compare the performance of the SAFE score and other non-invasive tests to diagnose liver fibrosis and to correlate the scores with liver-related outcomes in patients with NAFLD in Hong Kong. METHODS: This was a retrospective cohort study involving two data sets. The first cohort was a biopsy cohort of NAFLD patients (n = 279), and the second was a territory-wide cohort of NAFLD patients (n = 4603) retrieved from a territory-wide electronic healthcare database in Hong Kong. RESULTS: In detecting significant fibrosis, liver stiffness measured by transient elastography had the highest area under the receiver operating characteristic curve (AUROC) (.844), followed by SAFE score (.773). SAFE score had the highest AUROC among blood-based algorithms (.773 vs. .746 for FIB-4, .697 for APRI). Based on cut-off values of SAFE score (0 and 100 points), 854 (18.6%), 1596 (34.6%) and 2153 (46.8%) were in the low-, intermediate- and high-risk groups, respectively, in the territory-wide cohort. Six (.7%), 15 (.9%) and 59 (2.7%) developed liver-related events in those three groups respectively. Among patients who had liver-related events at 5 years, using the high cut-off, SAFE score could predict 84.9% of patients accurately, compared to 40.9% for FIB-4 and 27.2% for APRI. CONCLUSION: The SAFE score performed well and better than other blood-based markers in diagnosing significant fibrosis and predicting liver-related events in Asian patients with NAFLD.

Neglect, online invasive exploitation, and childhood sexual abuse in Hong Kong: Breaking the links.

BACKGROUND: Childhood sexual abuse (CSA) is a form of maltreatment that involves a child in sexual activity that she or he cannot fully comprehend or is unable to give informed consent to. The empirical link between child neglect and contact child sexual abuse is well established but little research examines mediators that explain this link. OBJECTIVE: This study tests online risk behaviors and unwanted sexual experiences online as sequential mediators of the neglect - CSA relationship. PARTICIPANT AND SETTING: The study uses a representative cross-sectional sample of 1097 Hong Kong adolescents. METHODS: Preacher and Hayes' (2008) non-parametric bootstrap approach was used to test three mediation hypotheses. RESULTS: Baseline logistic regression models showed neglected children had 11.2 times higher odds of reporting contact CSA (p < .001). Similarly, neglect was associated with 3.5 times higher odds of more online risk behavior (p < .001), which in turn was associated with 2.7 times higher odds of more online invasive exploitation (p < .001). Online invasive exploitation was associated with 2.7 times higher odds of reporting offline contact CSA (p < .001). The study found online risk behaviors to be a significant mediator of the relationship between neglect and online invasive exploitation (unwanted online sexual experiences). Online invasive exploitation, in turn, mediated the relationship between online risk behaviors and offline contact CSA. CONCLUSION: The findings highlight the importance of intervening against neglect as it appears to play a vital role in the etiology of contact CSA in Hong Kong.