Parental smoking, socioeconomic factors, and risk of invasive meningococcal disease in children: a population based case-control study.

AIMS To investigate the effects of parental smoking, socioeconomic characteristics, and indoor environment on the risk of invasive meningococcal disease in children. METHODS Population based case-control study. A total of 68 incident cases of invasive meningococcal disease in children less than 15 years old were compared with 135 controls selected from the same school and matched for year of birth, sex, and place of residence. Information on exposures was obtained in interviews with parents. RESULTS Invasive meningococcal disease was strongly associated with parental smoking; rate ratios adjusted for socioeconomic factors were 3.5 (95% confidence interval 1.4-8.7) for smoking of mother, 3.2 (1.5-6.9) for smoking of father, and 2.7 (1.3-5.4) for every 20 cigarettes smoked at home on an average day. The risk of the disease was strongly inversely related to maternal education and, less strongly, to ownership of a car and of a weekend house, father's education, crowding, and the number of siblings, but these associations were reduced or eliminated in multivariate models. The type of heating and cooking (used as proxies for indoor air pollution) were not associated with the disease. CONCLUSION The risk of invasive meningococcal disease in children is strongly influenced by parental smoking and unfavourable socioeconomic circumstances.