The influence of HBV infection status on such a risk has never been estimated accurately; the results of published studies may have been influenced by concomitant hepatotoxic pharmacotherapy, underlying disease, and other patient characteristics. [...]this study reflects the precise risk of ALT elevation in HBV-infected patients because most were prescribed anti-TNF agents before formal risk management guidelines were issued in Taiwan and, therefore, received no prior antiviral prophylaxis [28]. Furthermore, it is likely that studies from different countries used different treatment strategies and doses of hepatotoxic immunosuppressants [30-32]. [...]analysis of the risk of hepatitis in HBsAg+ subjects must take into account many potential risk factors, including sex, age, their underlying immune-mediated disease, and concomitant use of hepatotoxic drugs. First and foremost, ALT elevation does not necessarily reflect HBV reactivation, and lack of viral load data in most cases with elevated ALT is a major limitation to interpreting its clinical significance; for example, chronic liver cirrhosis is another possible cause of ALT elevation in HBsAg+ versus uninfected subjects. [...]although we investigated the effects of HBV serostatus and immunosuppressants as risk factors, we did not specifically evaluate the risk of immunosuppressant use in HBsAg+ patients, which is known to increase the risk of HBV reactivation [5].