[Case-control study of risk factors for cedar pollinosis among parents of 3-year-old children].

PURPOSE: To identify risk factors associated with cedar pollinosis among parents of three-year-old children. METHODS: The subjects were parents whose children underwent health examination at the age of three years in September and October 1997 in Tochigi prefecture. We distributed questionnaires to the examinees beforehand with the request that they be filled in and brought to the examination site. Information on parents' environmental factors (place of residence, type and structure of housing, and distance from roads with heavy traffic), and mothers' past history and family history of allergic diseases was obtained. We defined cedar pollinosis in terms of three symptoms, sneezing, nasal discharge, and nasal obstruction, between February and May. Controls were those who did not have any of the three symptoms. Environmental factors were assessed with univariate and multivariate analyses using unconditional logistic models. Maternal genetic factors were also analyzed with odds ratios and 95% confidence intervals calculated for each. We also compared odds ratios of environmental factors between groups with and without genetic factors. RESULTS: Of the parents of children taking the health examination, 90.2% took part (2,968 of 3,291 couples). Information was obtained from 2,846 mothers and 2,905 fathers. Mother and father cases were 312 and 229, and controls were 1,857 and 1,934, respectively. For the univariate analysis of environmental factors, place of residence (residential area/agricultural area), type of housing (apartment complex/solitary house), structure (reinforced concrete building/wooden house), and distance from heavy traffic (< 100 m/100 m+) were positively related to cedar pollinosis. For the multivariate analysis using unconditional logistic models, the odds ratio was significantly high for distance from heavy traffic (< 100 m/100 m+) among fathers. Mothers' past history and family history of allergic diseases showed high odds ratios for cedar pollinosis. We classified groups with and without past and family histories of allergic diseases (group with and without genetic factors) for assessment with multivariate analyses. Odds ratios for the group with an allergic history were higher than for those without such a history, but difference for factors such as, distance from heavy traffic type of housing, and structure were not statistically significant. CONCLUSION: Risk of cedar pollinosis increases with distance from heavy traffic among fathers. Mothers with histories of allergy show slightly elevated odds ratios for environmental factors, but without statistic significance.