Abstract
BackgroundIn Canada, targeted vaccination of at risk groups for hepatitis A (HA) is done since the mid 1990s resulting in declining incidence. This study estimated the year and age specific hospitalization rates and distribution of risk factors for HA in Quebec, Canada, between 1990 and 2003.MethodsRecords of patients hospitalized with HA-related diagnostic codes were retrieved from the provincial database. Hospital charts of all deceased cases and a random sample of all other records were reviewed.ResultsFrom 1503 hospitalization records, 573 charts were reviewed including 49 (91%) of the 54 deceased patients. Confirmed acute HA was present in 79% of records where HA was the primary diagnosis, and in 3%–8% of records where HA was a secondary diagnosis. From the total estimated number of hospitalizations, 96% had HA as the primary diagnosis. The hospitalization rate decreased from 1.06 per 100 000 person-years between 1990 and 1997 to 0.36 between 1998 and 2003. During the study period, 54% HA hospitalizations were in 20–39 year-olds. The overall case fatality ratio among hospitalized patients was 1.4%, increasing from 0.4% in those < 40 years old to 12.5% in those ≥60 years. By decreasing order, reported risk factors were travel to HA endemic countries (30%), MSM (18%) and household contacts (11%).ConclusionHA hospitalization rates have been low since 1998 but the cause of this is unclear given the cyclical pattern of HA. Travel to endemic countries remains the most important risk factor and improved control of HA will require better strategies to vaccinate travelers.
Highlights
In Canada, targeted vaccination of at risk groups for hepatitis A (HA) is done since the mid 1990s resulting in declining incidence
We reviewed a sample of medical charts of patients recorded in an administrative database as having been hospitalized with a diagnosis of HA between 1990 and 2003 in the province of Quebec, Canada, to validate the accuracy of the diagnosis
The median age was similar in patients whose charts were reviewed and the other patients (P = 0.55) when the diagnosis was in primary position but it was 4 years younger when the diagnosis was in any secondary position (P = 0.002)
Summary
In Canada, targeted vaccination of at risk groups for hepatitis A (HA) is done since the mid 1990s resulting in declining incidence. Hepatitis A exhibited a cyclical pattern with peaks in 1984, 1991 and 1996. Since 1990, incidence has been more similar to that of the country and displayed a synchrony regarding the peak years (Figure 1). These peak years occurred when two large outbreaks affected men who have sex with men (MSM) in Montreal [5,6]. After these outbreaks, the incidence declined substantially. It is hard to know if this was attributable to a larger use of the vaccine of if it is part of the normal HA cyclical pattern
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