Risk of Hepatitis Flare in Patients With Previous Hepatitis B Virus Exposure Amongst Patients
Risk of Hepatitis Flare in Patients With Previous Hepatitis B Virus Exposure Amongst Patients
The purpose of this study is to study the risk of hepatitis flare in patients with previous
 hepatitis B virus exposure amongst patients on immunosuppressive and biological modifier
 therapies
Chronic hepatitis B infection remains a global health threat despite vaccination program.[1]
 Nearly 3 billion population are infected with chronic hepatitis B infection globally. In
 China, the pooled prevalence of chronic hepatitis B infection was around 7% in year 2018,
 making an estimated 84 millions of population living with chronic hepatitis B infection.
 Hepatitis B virus infection is the leading cause of liver cirrhosis and hepatocellular
 carcinoma, leading to significant morbidity and mortality. Patients with hepatitis B
 infection can present with a wide range of clinical presentation, ranging from inactive
 carrier to fulminant hepatitis, cirrhosis or development of hepatocellular carcinoma.
 Besides, a significant proportion of patients are suffering from occult hepatitis B infection
 (OBI), which is defined as a state of undetectable serum HBsAg yet detectable serum and/ or
 intrahepatic HBV DNA. Report from the European Association for the Study of the Liver (EASL)
 in 2008 has revealed that around one-third of the global population has serological evidence
 of past or present HBV infection. Disappearance of HBsAg, also known as HBsAg seroclearance,
 can occur either spontaneously or after anti-viral treatment. However, patients with past or
 resolved HBV infection are still at risk of development of hepatocellular carcinoma, liver
 cirrhosis and liver-related mortality.The reported prevalence of OBI amongst patients with
 non-alcoholic fatty liver disease in Hong Kong was 35% (submitted to American Journal of
 Gastroenterology, under review). It is well known that there is risk of HBV reactivation
 after chemotherapy or immunosuppressive therapy which can lead to fulminant liver failure or
 even death. Short course of high dose corticosteroid could increase the risk of hepatitis
 flare in patients with chronic hepatitis B infection. Even in patients with OBI, a high daily
 dose of corticosteroid (>40mg prednisolone equivalents) increased risks of hepatitis flare.
 It is thus important to know the hepatitis B virus status before start of chemotherapy,
 immunosuppressive therapy or corticosteroid.

 Biologics is one of the mainstay treatments for many autoimmune diseases, including
 inflammatory bowel disease (IBD), rheumatoid arthritis (RA) and systemic lupus erythematosus
 (SLE), psoriasis etc. The incidence of IBD has increased rapidly in Hong Kong over the past
 30 years. The age-adjusted incidence of IBD in Hong Kong has rose from 0.10 per 100,000
 individuals in 1985 to 3.12 per 100,000 individuals in 2014. The reported prevalence of RA in
 Hong Kong was 0.35% while the reported prevalence of SLE in Hong Kong was 0.1% with annual
 incidence of 6.7 per 100,000 individuals. It is well known that treatment with biological
 agent like anti-CD20 monoclonal antibody (rituximab) in patients with OBI can lead to
 fulminant hepatitis B flare. Recently, anti-tumor necrosis factor alpha (TNF α) has been
 widely used in patients with inflammatory bowel disease and various rheumatological diseases.
 Risk of hepatitis B reactivation after anti-TNF α has been reported, but actual risk remains
 controversial. In a report from Japan including 135 rheumatoid arthritis patients with
 previous HBV infections, 17/135 (12.6%) had HBV reactivation after receiving
 immunosuppressants and patients who were treated with biologics were more frequent to develop
 HBV reactivation compared to those who were not on biologics. In another study, 9/168 (5%)
 anti-HBc positive patients developed HBV reactivation after receiving anti-TNF α and one
 patient died due to fulminant liver failure.However, another three studies revealed low rates
 of HBV reactivation (0-2%) amongst rheumatology patients with previous HBV infections
 receiving anti-TNF α. The European Crohn's and Colitis Organisation (ECCO) suggested routine
 antiviral prophylaxis for patients with previous HBV infection starting biologics is not
 recommended. Instead, regular monitoring of ALT/ AST, change in HBV serology and HBV DNA
 every 1 to 3 months should be performed. In 2015, the American Gastroenterology Association
 (AGA) has developed guideline on the prevention and treatment of hepatitis B virus
 reactivation during immunosuppressive therapy. It classifies patients receiving anti-TNF α as
 moderate risk of developing HBV reactivation and antiviral prophylaxis is preferred over
 monitoring alone, but it is a weak recommendation. Therefore, it is now still uncertain
 whether prophylactic anti-viral should be given for patients with previous HBV exposure
 before starting anti-TNF α.

 With the advancement of technology, there are now more biological agents and small molecules
 for the treatment of IBD and various rheumatological conditions. These include anti-integrin,
 cytokine inhibitors, and small molecules e.g. JAK inhibitors. Cytokine inhibitor, ustekinumab
 (anti-IL12/23), has been reported to be leading to hepatitis reactivation in a psoriasis
 patient who has past HBV infection.[26] Whether these agents can lead to hepatitis flare in
 patients with past HBV exposure remains largely unknown.

 Based on the compelling data, the investigators hypothesize that use of biologic modifier
 therapies in patients with occult hepatitis B infection will lead to hepatitis flare. The
 investigators aim to assess the rate of hepatitis flare while on biological modifier
 therapies in both retrospective population-based database and prospectively in patients who
 are on biological modifier therapies.
Inclusion Criteria:

 -  Age ≥ 18 years old at the time of starting biological modifier therapies or at the
 time of recruitment

 -  Positive for anti-HBc OR

 -  Positive for anti-HBs and born before year 1988

 Exclusion Criteria:

 -  Known HBV carrier with HBsAg positive

 -  Concomitant HCV and/ or HIV infection

 -  Already on HBV anti-viral

 -  Refuse to consent

 -  Baseline ALT > 80 IU/ml