Liver enzyme and hepatitis B 'e' antigen test results are sufficient to determine which people with hepatitis B need antiviral treatment for the infection in sub-Saharan Africa, a study carried out in West Africa has shown.
The findings, published in advance online by the Journal of Hepatology, show that expensive laboratory tests or Fibroscan equipment are not needed to determine which people are at higher risk of progressive liver disease and in need of treatment. Instead, blood tests costing less than $20 identified 85% of people in need of treatment.
Hepatitis B is endemic in many lower-income countries, especially in West Africa, and viral hepatitis now kills more people worldwide than either tuberculosis or HIV.
Glossary
- FibroScan
A non-invasive test, used instead of a biopsy, to measure the stiffness
or elasticity of the liver using an ultrasound probe.
- regression
Improvement in a tumour. Also, a mathematical model that allows us to measure the degree to which one of more factors influence an outcome.
Treatment of hepatitis B is now feasible using generic versions of antiviral drugs costing less than $50 a year. One of the major barriers to treatment is determining treatment eligibility. Not everyone with hepatitis B needs immediate treatment so, to test who is eligible, international guidelines recommend the use of hepatitis B virus (HBV) DNA tests to confirm viraemia and either liver biopsy or Fibroscan to test liver fibrosis.
The World Health Organization has recommended treatment for anyone with persistently elevated liver enzymes (ALT) and an APRI score of 2 or above. The APRI score is the ratio of AST to platelets and has been shown to predict cirrhosis with a high degree of accuracy. However, the scoring system requires several blood samples and clinic visits and may be more difficult to calculate.
Researchers associated with the UK Medical Research Council’s Gambia Hepatitis Intervention Study and institutions in France, Burkina Faso, Gambia, Senegal and Berlin investigated whether basic laboratory tests that could be carried out in any health facility and interpreted by all grades of staff provided sufficient information to accurately select people in need of treatment.
The study looked at possible predictors of treatment need in a cohort of 804 people with chronic HBV infection in the Gambia, recruited through community screening for a study of hepatitis B treatment between 2011 and 2014.
Analysis of the cohort found that seven factors independently predicted treatment eligibility. Further analysis using a regression model found that a scoring system using the following test results predicted treatment eligibility in the cohort:
- Positive hepatitis B surface antigen – 1 point
- ALT score < 20 IU/L – 0 point
- ALT score 20-39 – 1 point
- ALT score 40-79 – 2 points
- ALT score > 80 – 3 points
A score of 2 points was associated with a 19.6% probability of meeting European Association for the Study of the Liver criteria for treatment, a score of 3 points a 65.2% probability and a score of 4 points a 93.5% probability. Sensitivity and specificity analysis showed that a score of 2 was associated with a sensitivity of 85% and a specificity of 77% for detecting people in need of treatment. In other words, the new diagnostic test, called TREAT-B, was found to accurately identify HBV-positive people who require treatment in 85% of cases and could accurately identify those who do not need treatment in 77% of cases.
The study investigators say that the scoring system may allow task-shifting of hepatitis B treatment initiation to non-specialist doctors or nurses in settings where healthcare staff are limited. However, they also note that the findings still need to be tested in other regions of the world and in populations co-infected with HIV or hepatitis C or D.