Respiratory tract rather than cutaneous atopic allergy inversely associate with multiple sclerosis: A case-control study

Background It has been previously shown that genetic or environmental factors, which promote susceptibility to allergic conditions, prevent the development of Th1-mediated inflammatory disease of multiple sclerosis (MS). To investigate the prediction value of lifetime atopic allergy in development of the future MS, a case-control study was designed. Methods Cases and controls were interviewed between December 2007 and April 2008 and they were asked if they had symptoms or diagnosis of allergies (including respiratory tract allergy, RTA; coetaneous allergy, CA; food/drug allergy, FDA) before MS diagnosis. Results Of 390 participants (195 controls and 195 cases), 125 healthy controls (64.1%) and 105 cases (53.8%) reported history of at least one type of atopic allergy (P = 0.04). A positive history of RTA (OR 0.43; 95% CI 0.28-0.66) or FDA (OR 0.24; 95% CI 0.13-0.43) was inversely associated with the risk of MS. No statistically significant association was found between the history of CA and MS. Conclusions There is a significant inverse association between RTA and MS that is compatible with a Th1/Th2 imbalance. History of RTA can be considered as a clinically useful risk reducing factor of MS.