The authors have declared that no competing interests exist.
Conceived and designed the experiments: RM AM. Performed the experiments: RM JT DF. Analyzed the data: AM AS SPH EM. Contributed reagents/materials/analysis tools: AS. Wrote the paper: RM AM DF.
To analyze alcohol use, clinical data and laboratory parameters that may affect FIB-4, an index for measuring liver fibrosis, in HCV-monoinfected and HCV/HIV-coinfected drug users.
Patients admitted for substance abuse treatment between 1994 and 2006 were studied. Socio-demographic data, alcohol and drug use characteristics and clinical variables were obtained through hospital records. Blood samples for biochemistry, liver function tests, CD4 cell count, and serology of HIV and HCV infection were collected at admission. Multivariate linear regression was used to analyze the predictors of FIB-4 increase.
A total of 472 (83% M, 17% F) patients were eligible. The median age at admission was 31 years (Interquartile range (IQR) 27–35 years), and the median duration of drug use was 10 years (IQR 5.5–15 years). Unhealthy drinking (>50 grams/day) was reported in 32% of the patients. The FIB-4 scores were significantly greater in the HCV/HIV-coinfected patients (1.14, IQR 0.76–1.87) than in the HCV-monoinfected patients (0.75, IQR 0.56–1.11) (p<0.001). In the multivariate analysis, unhealthy drinking (p = 0.034), lower total cholesterol (p = 0.042), serum albumin (p<0.001), higher GGT (p<0.001) and a longer duration of addiction (p = 0.005) were independently associated with higher FIB-4 scores in the HCV-monoinfected drug users. The effect of unhealthy drinking on FIB-4 scores disappeared in the HCV/HIV-coinfected patients, whereas lower serum albumin (p<0.001), a lower CD4 cell count (p = 0.006), higher total bilirubin (p<0.001) and a longer drug addiction duration (p<0.001) were significantly associated with higher FIB-4 values.
Unhealthy alcohol use in the HCV-monoinfected patients and HIV-related immunodeficiency in the HCV/HIV-coinfected patients are important risk factors associated with liver fibrosis in the respective populations
Liver fibrosis is the main predictor of whether chronic hepatitis C will progress to cirrhosis and end-stage liver disease
The cofactors associated with chronic hepatitis C progression differ among studies; alcohol abuse, male gender, age at infection, body mass index, and coinfection with human immunodeficiency virus infection (HIV) and Hepatitis B virus infection (HBV) have been related to more rapid disease progression
In HIV-negative patients, it is well established that alcohol abuse and HCV infection have a synergistic effect on liver fibrosis. However, there are conflicting results regarding the independent effect of alcohol on liver damage in HCV/HIV-coinfected patients
Liver biopsy is the gold standard for assessing fibrosis
Several non-invasive markers of liver fibrosis have been proposed as alternatives to liver biopsy. Some of these markers reflect the modified extracellular matrix turnover that occurs during fibrogenesis
Although abuse of alcohol and illegal drugs is frequent in patients with HIV infection and HCV infection, it is unclear how non-invasive liver fibrosis tests may reflect disease progression. In this study, we hypothesize that certain clinical and laboratory characteristics may influence a simple index of fibrosis and that the cofactors associated with elevated FIB-4 scores may differ between HCV-monoinfected patients and HCV/HIV-coinfected patients. Hence, the primary objective of the study was to characterize the putative differences in risk factors for elevated liver function biomarkers between HCV-monoinfected and HCV/HIV-coinfected patients.
This was a cross-sectional study of patients admitted for substance abuse treatment between 1994 and 2006. The demographic and drug use characteristics were recorded through a structured questionnaire administered by a physician the day of admission. Questions related to drug and alcohol abuse included: (i) the main drug of abuse (type of drug, age at first use, duration of drug use and route of administration), (ii) poly-drug use (yes/no) (iii) alcohol consumption: do you regularly drink alcohol? (yes/no); if yes, do you drink 5 or more standard drinks per day?. A standard drink unit contains 12–14 grams of alcohol and unhealthy alcohol consumption was defined as a daily alcohol intake ≥50 grams (g)
Routine laboratory parameters, including liver function tests and serology for HIV infection and HCV infection, were analyzed at admission. Other characteristics of admission for substance abuse treatment have been described elsewhere
The liver function tests and biochemical parameters were assessed using an Olympus 5200 Multichannel chemistry analyzer. The procedure, which remained the same throughout the study, was based on the reference method recommended by the International Federation of Clinical Chemistry.
HIV infection was identified by an enzyme-linked immunosorbent assay. Repeatedly reactive samples were confirmed by the Western immunoblot technique.
HCV infection was assessed prior to or during admission by a second- or later-generation enzyme immunoassay (Ortho Diagnostics, Raritan, NJ). The positive samples were confirmed by either a recombinant immunoblot assay (RIBA HCV 2 SIA, Chiron Corporation, Emeryville, CA) or a qualitative/quantitative assay (COBAS AMPLICOR, Roche Diagnostic Systems, Branchburg, NJ).
The primary outcome was the FIB-4 score, which was calculated as
FIB-4 scores lower than 1.45 indicate lack of liver fibrosis with a negative predictive value of 90% and a sensitivity of 70%
All of the analyses were conducted separately for the HCV-monoinfected (N = 228) and the HCV/HIV-coinfected (N = 244) individuals. We used medians and interquartile ranges (IQRs) to describe the quantitative variables and absolute frequencies and percentages to describe the qualitative variables.
The distribution of FIB-4 score was strongly skewed to the right (i.e., there were several very high values); we therefore normalized it for analysis purposes using a logarithmic transformation.
We used multiple linear regression models to determine the FIB-4 predictive values of the variables. There were three types of predictors: (1) binary, which included sex, alcohol use, and HBsAg; (2) continuous on a natural (additive) scale, which included body mass index (BMI), CD4 cell count, total cholesterol, alkaline phosphatase, and duration of drug use; and (3) continuous on a logarithmic (multiplicative) scale, which included total bilirubin, serum albumin, and GGT. The decision to analyze a variable using a logarithmic scale was based on the need to reduce the undue influence of high values in predictors with strong right skewness.
The interpretation of the regression coefficients differed among the three types of predictors. Specifically, the regression coefficients of the binary variables represented the percentage FIB-4 difference between those with and without the condition; the regression coefficients of the additive continuous variables represented the percentage FIB-4 difference associated with an unitary increase or decrease in the variables, and the regression coefficients of the multiplicative continuous variables represented the percentage FIB-4 difference associated with an increment or decrement in the variables.
The intercept represented the expected FIB-4 score in an individual with zero values for all of the predictors.
The test results were considered to be statistically significant if the resulting P-
Patients were eligible for this study if they had chronic HCV infection (N = 544). Patients with aminotransferase levels 10 times greater than the upper limit of the normal range (N = 5,1.0%), patients who had received HCV antiviral therapy (N = 6,1.1%) and patients with antecedent of decompensated liver cirrhosis (N = 10,1.8%) were excluded. In addition, patients with an HCV-RNA level below the limit of detection (<50 IU/mL) were excluded (N = 9, 1.7%). Finally, patients with outlier laboratory values and those with incomplete data for calculating FIB-4 score were also excluded (N = 42, 7.7%). After these exclusions, the study population consisted of 472 patients and 244 patients (52%) were coinfected with HIV.
HCV | HCV/HIV | Total | ||
N = 228 | N = 244 | p_value |
N = 472 | |
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35 (15.4%) | 45 (18.4%) | 0.371 | 80 (16.9%) |
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30 |
31.5 [28, 35] | 0.008 | 31 [27, 35] |
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22.3 [20.7, 24.6] | 21.6 [19.6, 23.6] | 0.000 | 21.9 [20.2, 23.9] |
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62 (28.2%) | 79 (35.9%) | 0.082 | 141 (32.0%) |
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7.6 [3.5, 12.0] | 12.0 [7.6, 16.0] | 0.000 | 10.0 [5.5, 15.0] |
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9 (4.2%) | 15 (6.7%) | 0.243 | 24 (5.5%) |
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162 [143, 178] | 149 [128, 170] | 0.001 | 155 [135, 174] |
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70 [55, 82] | 70 [59, 86] | 2.664 | 70 [56, 84] |
|
0.4 [0.3, 0.6] | 0.4 [0.3, 0.6] | 0.297 | 0.4 [0.3, 0.6] |
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39 [36, 42] | 38 [35, 41] | 0.013 | 39 [36, 41] |
|
33 [19, 62] | 44.5 [24, 93] | 0.052 | 38 [22, 76] |
1225 [933, 1428] | 383 [204, 661] | 0.000 | 742 [350, 1225] | |
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||||
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197 [166, 243] | 163 [127, 196] | 0.000 | 180 [146, 224] |
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33.5 [21.0, 61.0] | 37.5 [24.2, 61.0] | 0.907 | 35.0 [23.0, 61.0] |
|
54.0 [23.0, 98.0] | 43.0 [25.0, 71.0] | 0.001 | 47.0 [24.0, 84.0] |
p value for the comparison between HCV-monoinfected and HCV/HIV-coinfected patients; p values correspond to χ square test in categorical variables and t test for differences of mean values in continuous variables.
Thirty-one percent of the HIV-positive patients were receiving antiretroviral therapy at admission, and 48% had never received antiretroviral therapy.
The median FIB-4 score at admission was 0.93 (IQR 0.65–1.46); it was significantly higher in the HCV/HIV-coinfected patients (1.14, IQR 0.76–1.87) than in the HCV-monoinfected patients (0.75, IQR 0.56–1.11).
We conducted univariate regressions of the variables shown in
HCV-monoinfected | HCV/HIV-coinfected | |||
N = 228 | N = 244 | |||
Univariate | Multivariate | Univariate | Multivariate | |
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NA | 0.778 |
NA | 0.875 |
(95% CI : 0.705, 0.861) | (95% CI: 0.762, 1.005) | |||
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−11.6% (0.266) | +11.5% (0.343) | ||
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+3.9% (0.695) | |
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+25.1% (0.268) | +31.3% (0.155) | ||
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+2.2% (0.069) | +0.8% (0.609) | |
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+2.4% (0.318) |
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+2.7% (0.108) |
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+0.9% (0.618) | |
NA | NA |
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|
|
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+5.7% (0.097) |
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+7.3% (0.061) |
Expected value of FIB-4 for individuals with predictors at BMI = 22 kg/m2, no alcohol consumption, total cholesterol = 155 mg/100 mL, Total bilirubin = 0.4 mg/dL, albumin = 39 g/L, GGT = 38 U/L, and duration of IDU = 10 years.
Expected value of FIB-4 for individuals with predictors at CD4 = 900 cells/µL, total cholesterol = 155 mg/100 mL, total bilirubin = 0.4 mg/dL, albumin = 39 g/L, Alkaline Phosphatase = 70 U/L, GGT = 38 U/L, and duration of IDU = 10 years.
In the univariate models for the HCV-monoinfected patients, unhealthy alcohol use, higher BMI, longer duration of drug use, lower cholesterol, higher bilirubin, lower albumin, and higher GGT were significantly associated (p<0.05) with higher FIB-4 scores. In the coinfected patients, higher FIB-4 scores were found to be significantly associated (p<0.05) with a longer drug use duration, lower cholesterol, higher alkaline phosphatase, lower CD4 cell count, higher bilirubin, lower albumin, and higher GGT.
For each group, the variables that showed significant relationships in the univariate analyses were used in a multivariate model. In the multivariate model for the HCV-monoinfected patients, unhealthy alcohol use (p = 0.034), longer drug use duration (p = 0.005), lower cholesterol (p = 0.042), lower albumin (p<0.001), and higher GGT (p = 0.001) continued to be significantly associated with higher FIB-4 scores.
In the coinfected patients, longer drug use duration (p<0.001), lower CD4 cell count (p = 0.007), higher bilirubin (p<0.001), and lower albumin (p<0.001) were significantly associated with higher FIB-4 scores.
Longer drug use duration and lower albumin levels were significantly associated with increased FIB-4 scores in both groups. By contrast, unhealthy alcohol use was strongly predictive of high FIB-4 scores only in the HCV-monoinfected group; similarly, high total bilirubin levels were associated with higher FIB-4 scores only in the coinfected patients.
Although the primary aim of the study was the characterization of the variables that were associated with FIB-4 increase in HCV-monoinfected and HCV/HIV-coinfected, the intercepts of the multivariate models provide a means of comparing a hypothetical HCV-monoinfected individual with a hypothetical HCV/HIV-coinfected individual, assuming that both have 900 CD4 cells/µL and that all of the other variables are equal. The slightly increased FIB-4 intercept value (0.778 in the monoinfected and 0.875 in the coinfected patients) was not statistically significant (p = 0.218). However, for each decline of 100 CD4 cells/µL among the coinfected patients, there was a significant FIB-4 increase of 3.6% (p = 0.007) (
To further characterize the differential effect of unhealthy alcohol use on FIB-4 scores,
Individuals with histories of drug use account for the majority of new hepatitis C infections in Western countries. This population is at risk for liver fibrosis, and a number of disease progression cofactors highlight the relevance of medical assessment. Evaluating liver fibrosis via non-invasive tests early in the course of drug addiction may increase the proportion of patients who are eligible for treatment. This study of young adults with chronic hepatitis C shows that the factors associated with higher FIB-4 scores clearly differed between the HCV-monoinfected and HCV/HIV-coinfected individuals.
The main contribution of the study is related to the fact that unhealthy alcohol use had a differential effect on FIB-4 values if patients have hepatitis C alone or HCV/HIV coinfection. Unhealthy alcohol drinking has been regarded as a major contributor to the progression of liver disease in the setting of chronic hepatitis C
In coinfected patients with unhealthy alcohol consumption, the FIB-4 does not reflect the negative impact of alcohol intake on liver fibrosis. Therefore, clinicians may not be able to assess the impact of ethanol nor can advise the patient on the risk of disease progression. On the contrary, unhealthy alcohol use is reflected in the FIB-4 of the monoinfected patients thus making possible preventive interventions to reduce harm.
Unhealthy alcohol use in the HCV-monoinfected patients and HIV-related immunodeficiency in the HCV/HIV-coinfected patients are the most important cofactors associated with fibrosis progression in the respective populations. In addition, we found that drug use duration and serum albumin were correlated with the FIB-4 scores of both the monoinfected and coinfected patients, whereas unhealthy alcohol use, GGT and total cholesterol were associated with higher FIB-4 scores only in the monoinfected patients. The effect of HIV-related immunodeficiency in the coinfected patients was strong (an increase of 3.5% in the FIB-4 score for every 100 CD4 cells/µL decrease). Furthermore, we did not observe differing FIB-4 values between the HCV-monoinfected and coinfected individuals with CD4 cell counts above 900 cells/µL. This observation suggests that FIB-4 elevation is associated with immunoactivation and the resulting decrease of CD4 cell counts in HCV/HIV-coinfected drug users.
The relationship between HIV-related immunodeficiency and liver fibrosis progression has been described in coinfected patients
In this study, decreased serum albumin and increased total bilirubin were associated with elevated FIB-4 scores. This finding may facilitate identifying a subpopulation of patients at increased risk for cirrhosis. It is well known that albumin and bilirubin are key components of the Child-Turcotte-Pugh score that clinicians use to assess decompensated liver cirrhosis.
In individuals with history of injection drug use, the duration of injection use is a surrogate for the duration of HCV infection
It has been reported that HCV infection itself lowers both low-density lipoprotein (LDL) and total cholesterol and that patients treated for chronic hepatitis C had larger increases in LDL and total cholesterol from baseline
This study has a number of limitations that should be mentioned. First, the alcohol intake assessment was limited to one categorical variable (>50 g/day, ≤50 g/day in the 6-month period before admission), and there was no information on the history and complications of alcohol consumption. In previous studies, however, recent alcohol consumption has been treated as a dichotomous variable using a threshold of 40–50 grams of ethanol per day or using the definition of heavy alcohol intake provided by the US National Institute on Alcohol Abuse and Alcoholism (NIAAA)
In summary, this study shows that unhealthy alcohol use strongly influence FIB-4 in HCV- monoinfected patients, whereas in the context of HCV/HIV coinfection, HIV-related immune depression exerts a major negative role on FIB-4 results, with no significant worsening by alcohol intake.