Association between population prevalence of smoking and incidence of meningococcal disease in Norway, Sweden, Denmark and the Netherlands between 1975 and 2009: a population-based time series analysis

Objective To investigate the relationship between the prevalence of smoking in the population and incidence of invasive meningococcal disease (IMD) among children under 5 years of age. Design Retrospective, longitudinal, observational study. Poisson regression controlled for confounding factors. Setting Norway, Sweden, Denmark and the Netherlands between 1975 and 2009. Population Total population of approximately 35 million people in these four countries. Data sources Data were collected from the Ministries of Health, National Statistics Bureaus and other relevant national institutes. Results In Norway, there was a significant positive relationship between the annual prevalence of daily smokers among individuals aged 25–49 years and the incidence of IMD in children under 5 years of age, unadjusted (RR=1.04–1.06, 95% CI 1.02 to 1.07, p