Page 221 - SAHCS HIVMed Journal Vol 20 No 1 2019

Page 2 of 6 Original Research

unavailability of routine, non-invasive and affordable Infections Clinic, Harare, Zimbabwe. All our participants
screening methods. Liver fibrosis gives rise to liver disease were HIV-infected and on ART for at least six months. Non-
owing to the excessive deposition of extracellular matrix ambulatory patients, tuberculosis co-infected patients and
8
(ECM) on the hepatocytes. The process is gradual and not pregnant women were excluded from the study. On
life-threatening until very late stages of the disease. enrolment, a questionnaire was administered to obtain
medico-demographic data from each participant. Five
The invasive liver biopsy (LB) is the gold standard method millilitres (mL) of blood were collected from each participant
for assessing liver fibrosis but lacks a standard interpretation into plain tubes and samples were centrifuged and had
protocol. This makes interpretation of results subjective and serum aliquoted within 2 h of bleeding.
often inaccurate. 9,10,11 Furthermore, liver histology gives a
limited picture of only that portion of the liver from which One aliquot of serum was immediately analysed for ALT,
the biopsy is derived. In contrast, the less invasive serum or AST, g-glutamyl transferase (GGT), total bilirubin (TBil) and
plasma biomarkers of liver function, such as enzymes, HBV, whilst another aliquot was immediately frozen and
provide a preview of the entire status of the liver. 12,13 kept at −80 °C for six weeks before measurement of
Consequently, serum biomarkers are thought to offer a better haptoglobin, apolipoprotein A-1 (Apo A-1) and alpha-2
alternative, as there are simple tests that are readily available, macroglobulin (A-2M) concentrations. Another 5 mL of blood
reproducible, easy to apply and, if well validated, can be were collected in ethylenediaminetetraacetic acid (EDTA)
effectively used to follow up and monitor patients. 9,14 tubes and analysed for platelet count within 3 h of
However, individual biomarkers of liver damage are limited phlebotomy.
predictors of hepatic fibrosis, 15,16 hence mathematical models
that combine routinely available individual biomarkers and Laboratory analysis
patient parameters into scores have been developed to Platelet count was determined using a Sysmex XT-4000i
improve the sensitivity and specificity of detection of fibrosis. automated Hematology analyser (Sysmex Corporation,
8
These models form algorithms such as the FibroTest, Kobe, Japan). Haptoglobin, Apo A-1 and A-2M concen-
Fibrosis-4 (FIB-4) index, aspartate aminotransferase to trations were determined using the sandwich enzyme-
alanine aminotransferase (AST: ALT) ratio and aspartate linked immunosorbent assay (ELISA) method (Elabscience
aminotransferase to platelet ratio index (APRI) test. 8,17
Biotechnology Co., Ltd, Wuhan, China). The serum activities
of ALT, AST, GGT and TBil concentration were determined
FibroTest is a patented, non-invasive algorithm that has been using the Beckman Coulter AU680 Chemistry analyser
shown to accurately predict liver fibrosis in different (Beckman Coulter, Inc., Mishima, Japan). Hepatitis B virus
aetiologies of liver disease. 10,18 FibroTest results have been status was determined using the Hightop one step rapid
shown to be comparable to the LB findings and have been HBV (5-in-1) test kit (Qingdao Hightop Biotech Co., Ltd,
used as an alternative diagnostic method in predicting liver Shandong, China). All assays were performed following the
fibrosis in several countries since 2002. 19,20 Not so much the manufacturer’s instructions.
other algorithms despite their potential to improve access to
diagnosis of liver fibrosis. Furthermore, these algorithms
have not been validated in non-Caucasian populations, and Algorithms for detection of fibrosis
their utility in African populations is sparsely reported in The specific formulae used to determine the algorithm scores
literature. are shown in Table 1.

Transient elastography also referred to as the Fibroscan is Statistical analysis
another non-invasive, highly acceptable, rapid and painless
method of assessing liver fibrosis. 21,22 The technique is not The Mann-Whitney test was used to compare non-parametric
serum or plasma based, but it uses both ultrasound and low- continuous variables between participants with significant
frequency elastic waves to quantify liver fibrosis. The method fibrosis and those without. Kappa test was used to assess
has been validated for liver fibrosis staging in patients with degree of agreement between algorithms. Cut-off values for
chronic liver diseases. The method is increasingly used in significant hepatic fibrosis were as follows: APRI test > 0.5,
21
Europe; however, there are limited data on its utility in FIB-4 index ≥ 1.45, FibroTest ≥ 0.32 and AST:ALT ratio > 1.
22
African populations. The present study aimed to determine
the prevalence of significant liver fibrosis in ART-experienced TABLE 1: Formulae of non-invasive algorithms for detection of fibrosis used in
the study.
individuals using four serum-based algorithms and Formula Equation
comparing their performance. FibroTest 4.467 × log[A-2M (g/L)] – 1.357 × log[Haptoglobin (g/L)] + 1.017 ×
log[GGT (IU/L)] + 0.0281 × [Age (years)] + 1.737 × log[TBil
(µmol/L)] – 1.184 × [Apo A-1 (g/L)] + 0.301 × Gender
Materials and methods (Female = 0, Male = 1) – 5.540 (www.biopredictive.com)
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Study participants and sample collection FIB-4 index [Age (years) × AST (IU/L)]/[Platelets (× 10 /L) × √ALT (IU/L)]
APRI test
[(AST (IU/L)/ ULN)/Platelet count (× 10 / L)] × 100
9
Between June and September 2014, we prospectively AST: ALT ratio AST/ALT
recruited 79 consecutive individuals from Harare Central ULN, upper limit of normal, ULN of AST: 42 IU/L (according to the local laboratory standards);
Hospital and Parirenyatwa Group of Hospitals Opportunistic APRI, aminotransferase to platelet ratio index; FIB-4, Fibrosis-4 index; AST, aspartate
aminotransferase; ALT, alanine aminotransferase.
http://www.sajhivmed.org.za 214 Open Access