Abstrak: In a national cohort comprising 1.5 million Danes born from 1966 to 1992, we studied the association between childhood socioeconomic status (SES) and the risk of multiple sclerosis (MS) from 1981 to 2007 using information about household income and parental educational levels at the person's 15th birthday. The association between childhood SES and MS was evaluated using MS incidence rate ratios with 95% confidence intervals obtained in log-linear Poisson regression analyses. We found no strong association between childhood SES and MS but did observe a tendency toward a reduced risk of MS among children from households with more highly educated parents, particularly mothers. Children whose mothers had a secondary (rate ratio = 0.95, 95% confidence interval: 0.86, 1.04) or higher (rate ratio = 0.86, 95% confidence interval: 0.76, 0.97) education had reduced risks of MS (5% and 14%, respectively) compared with children of mothers with a basic education (P for trend = 0.02). Results were practically unchanged in an analysis restricted to persons aged 15-29 years, among whom the possible effect of own SES on MS risk is considered limited. Overall, SES in childhood seems of no major importance for the subsequent risk of MS; however, offspring of well-educated mothers may be at a slightly reduced risk of MS.

Abstrak: Inconsistent evidence exists regarding the association between work-related factors and risk of multiple sclerosis (MS). We examined the association between occupational exposures and risk of a first clinical diagnosis of central nervous system demyelination (FCD), which is strongly associated with progression to MS, in a matched case-control study of 276 FCD cases and 538 controls conducted in Australia (2003-2006). Using a personal residence and work calendar, information on occupational history and exposure to chemicals and animals was collected through face-to-face interviews. Few case-control differences were noted. Fewer cases had worked as professionals (≥6 years) than controls (adjusted odds ratio (AOR) = 0.60, 95% confidence interval (CI): 0.37, 0.96). After further adjustment for number of children, cases were more likely to have ever been exposed to livestock than controls (AOR = 1.54, 95% CI: 1.03, 2.29). Among women, there was an increase in FCD risk associated with 10 or more years of exposure to livestock (AOR = 2.78, 95% CI: 1.22, 6.33) or 6 or more years of farming (AOR = 2.00, 95% CI: 1.23, 3.25; also adjusted for number of children). Similar findings were not evident among men. Thus, farming and exposure to livestock may be important factors in the development of FCD among women, with this finding further revealed after the confounding effect of parity or number of children is considered.

Abstrak: In this study, we describe the geospatial variation in the incidence of multiple sclerosis (MS) in Manitoba, Canada, and the sociodemographic characteristics associated with MS incidence. By using administrative health data, we identified all incident cases of MS in Manitoba from 1990 to 2006 (n = 2,290) and geocoded them to 230 neighborhoods in the City of Winnipeg and 268 municipalities in rural Manitoba. Age-standardized incidence rates for 1990–2006 (combined) were calculated for each region. By using the spatial scan statistic, we identified high-rate clusters in southwestern (incidence rate ratio (IRR) = 1.48) and central Winnipeg (IRR = 1.54) and low-rate clusters in north-central Winnipeg (IRR = 0.52) and northern Manitoba (IRR = 0.48). Multivariable Poisson regression showed a positive association between MS incidence rates and socioeconomic status. Despite our finding that MS incidence varied geographically and by socioeconomic status, the low Gini coefficient of 0.152 for MS incidence identified in this study suggests that the causes of MS are pervasive across all population groups. Searching for local-level causes of the disease may therefore not be as productive as investigating etiological factors operating at the population level. This may require an examination of macro-level differences in environmental exposures between high- and low-incidence regions of the world.