The risk for multiple sclerosis in female nurse anaesthetists: a register based study.

BACKGROUND Previous studies have suggested that exposure to organic solvents, including volatile anaesthetic agents, may be a risk factor for multiple sclerosis (MS), possibly in combination with genetic and other environmental factors. AIMS To further investigate the role of volatile anaesthetic agents having similar acute toxic effects to other organic solvents. METHODS Female nurse anaesthetists, other female nurses, and female teachers from middle and upper compulsory school levels were identified and retrieved from the 1985 census, Statistics Sweden. By means of the unique personal identity number in Sweden, these individuals were linked with the disability pension registers at The National Social Insurance Board and also with data on hospital care 1985-2000 at The National Board of Health and Welfare. RESULTS The cumulative incidence rate ratio of MS was found to be increased in female nurse anaesthetists in relation to other nurses (statistically not significant) and teachers (statistically significant), respectively. CONCLUSIONS These findings give some support to previous findings of an increased risk for MS in nurse anaesthetists. This is interesting in the context of previous observations of organic solvents in general as a potential risk factor in MS.