Examining the association between neighbourhood characteristics and gonorrhea rates among women aged 15 to 24 years in Montreal, Canada.

OBJECTIVE The reported incidence rate of gonorrhea has more than doubled from 2000 to 2010 in Montréal, increasing in both sexes and all age groups; however, the increase was particularly high in females aged 15 to 24 years. As the reasons for this increase among young women are not fully understood, we wanted to determine whether neighbourhood-level population characteristics were associated with incidence rates in this group, to help target intervention strategies. METHODS Incident gonorrhea cases were female residents of Montréal aged 15 to 24 years who met Québec's gonorrhea surveillance definition, with a notification date from 2002 to 2009. Adjusted incidence rate ratios (IRR) were estimated by negative binomial regression and show the change in the incidence of gonorrhea for each unit increase in neighbourhood-level independent variables, which included material and social deprivation indices (plus the latter's combination and components) and ethnic origin. In the final model, independent variables were normalized to facilitate comparison of their respective IRRs. RESULTS A total of 837 cases were reported (cumulative incidence rate 5.6 per 100,000). Higher proportions of persons of African, Aboriginal and Caribbean ethnicity were associated with higher rates of gonorrhea, even after adjustment for deprivation indices. CONCLUSION Customary methods for gonorrhea surveillance consider individual characteristics of cases as risk factors for disease. However, our results show that gonorrhea is clustered in neighbourhoods that have high proportions of three ethnic origin groups. Findings from this ecological approach suggest that although ethnicity may be strongly correlated with socio-economic status, there are factors in ethnicity that transcend poverty.