Evaluating Liver Fibrosis Progression and the Impact of Antiretroviral Therapy in HIV and Hepatitis C Coinfection Using a Noninvasive Marker

The effects of highly active antiretroviral therapy (HAART) on progression of hepatic fibrosis in hepatitis C virus (HCV) coinfection with HIV are not well understood and are difficult to measure because of the need for repeated liver biopsy. We evaluated the evolution of a noninvasive measure of liver fibrosis, the alanine aspartyl transferase (AST)-to-platelet ratio index (APRI), longitudinally and determined its predictive value for hepatic outcomes in HIV-positive patients with and without HCV coinfection. A total of 673 HIV-positive patients without liver complications at baseline (540 with HIV only, 133 with HIV-HCV coinfection) were followed between 1991 and 2004 for a median of 4.6 years (3524 person-years). At baseline, HIV-HCV coinfection had a higher median APRI compared with HIV infection alone (0.59 vs. 0.33; P < 0.0001). The natural logarithm of the APRI [ln(APRI)] changed significantly over time, particularly among patients with HIV-HCV coinfection. The baseline ln(APRI) was predictive of liver complications (hazard ratio [HR] = 4.0, 95% confidence interval [CI]: 2.5 to 6.4 per log), as was HCV (HR = 4.5, 95% CI: 1.5 to 14). Cumulative HAART did not protect against liver complications, although it was significantly associated with progression of APRI scores in HIV-HCV coinfection and in HIV alone. In conclusion, the APRI may be a useful marker for longitudinal evaluation of the progression of liver disease in HIV-HCV coinfection.

Validation of a simple model for predicting liver fibrosis in HIV/hepatitis C virus-coinfected patients

OBJECTIVES

Recently, several models incorporating laboratory measurements have been validated for use as surrogate markers for liver fibrosis in hepatitis C virus (HCV) mono-infection, the simplest of these being the aspartate aminotransferase (AST) to platelet ratio index (APRI). We evaluated how well the APRI predicts significant hepatic fibrosis in patients with HIV/HCV coinfection.

METHODS

Forty-six HIV/HCV-coinfected patients who underwent liver biopsy and had concomitant laboratory measurements (+/-3 months) were included in the study. Significant fibrosis was defined as F2-F4 using Batt and Ludwig scoring (=3 Ishak). APRI=[(AST/upper limit of normal)/platelet count (10(9)/L)] x 100. We used sas proc logistic (SAS Institute, Cary, NC) to calculate the area under the receiver operating curve (ROC) (AUC). Sensitivities, specificities, positive predictive value (PPV) and negative predictive value (NPV) were compared using cut-offs previously identified in the literature.

RESULTS

Thirty-three of 46 patients (72%) had significant fibrosis on biopsy. For significant fibrosis, the area under the ROC for the APRI was 0.847+/-0.057. APRI scores >1.5 (the higher cut-off) were 100% specific and 52% sensitive; PPV was 100% and NPV 45%. Scores <0.5 (the lower cut-off) were 82% sensitive and 46% specific in ruling out significant fibrosis (PPV 79%; NPV 50%).

CONCLUSIONS

A simple model incorporating readily available laboratory data is highly predictive of significant fibrosis in HIV/HCV coinfection and could serve as a biopsy-sparing measure, thus making treatment more accessible for this population.