An exploratory analysis of individuals with multiple episodes of different reportable diseases, Montreal, 1990–2012

Abstract Objectives Studies of public health reporting have only examined multiple episodes of the same communicable disease within an individual. We aimed to characterize Montreal residents with multiple reportable disease episodes from 1990 to 2012, while accounting for all types of reportable diseases. Study design Retrospective cohort study. Methods We performed an exploratory analysis using descriptive statistics, contingency tables, and logistic regression. Results There were 157,839 individuals with at least one disease report and a total of 179,455 disease reports. The 9.8% of subjects with more than one episode accounted for 20.7% of all reported episodes. Among subjects with four or fewer episodes, 54.0% were women, while 74.3% of subjects with five or more episodes were men. Subjects with multiple episodes were more likely to be reported for sexually transmitted infections than were persons with a single episode [difference of proportions: 10.4% (95% CI: 10.0%–10.9%)] and to reside in the neighbourhood encompassing Montreal's gay village. Conclusions Individuals with multiple communicable disease reports place a large burden on public health officials. These results may help guide investigation and prevention efforts to reduce the number of excess episodes.