Our algorithm is designed to minimize these sources of false positives by excluding patients with prior positive hepatitis B tests or an ICD9 code for chronic infection in their electronic medical records. These exclusion criteria combined with the rarity of cholestasis in severe flares of chronic hepatitis B likely account for the high specificity of our algorithm despite case reports of jaundice in flares of chronic infection. It is unlikely that the physician chart reviewer��s subjective judgment of acute versus chronic disease influenced the relative performance of the algorithms. Serial hepatitis B surface antigen tests were Oxytocin (Syntocinon) available for 82% of patients; the patterns of change in surface antigenemia over time confirmed the physician reviewer��s clinical impression in all cases in which serial tests were available. These confirmatory changes in surface antigenemia decrease the likelihood that acute cases of anicteric disease were misclassified as chronic infections. Previous studies suggest that some cases of acute hepatitis B are clinically silent. These patients were likely missed by this analysis since by definition it was limited to patients who Neohesperidin presented for clinical evaluation. Our algorithms do incorporate a strategy for seeking clinically silent acute cases of disease but this strategy is still contingent upon patients with silent disease presenting for clinical care and eliciting sufficient clinical suspicion to prompt serial surface antigen testing. These are admittedly rare circumstances. The poor positive predictive value of ICD9 code 070.30 for acute hepatitis B is likely an artefact of the text description given to this code in our practice��s electronic medical record. It is labelled as ����hepatitis B���� alone rather than ����acute hepatitis B���� and hence is commonly used by clinicians for asymptomatic patients found to have evidence of remote exposure to hepatitis B or ongoing chronic disease despite the presence of a specific alternative code for chronic disease.These false positives are consistent with previous studies in which patients with flares of chronic hepatitis B occasionally present with very high transaminases and bilirubin. Davis and Hoofnagle, for example, prospectively followed 150patients with chronichepatitisB and found that two developed clinical jaundice from flares of their hepatitis B.