Fine Particulate Matter Related to Multiple Sclerosis Relapse in Young Patients.

Objective

Particulate matter (PM) of aerodynamic diameter smaller than 10 μm (PM10) has been associated with multiple sclerosis (MS) relapse. However, the impact of smaller PM with a greater ability to penetrate human organism has never been assessed. We evaluated the impact of PM smaller than 2.5 μm (PM2.5) on the risk of MS relapse. Material and

Methods

In a case-crossover study, we included 2,109 consecutive hospitalizations likely due to MS relapse in day hospital in 5 MS centers in the Paris area from January 2009 to December 2013. For each hospitalization, the natural logarithm of the average weekly PM2.5 concentrations (μg/m3) at the patient's residence address during each of the 6 weeks (week[0] to week[-5]) preceding admission was compared with the concentration during the previous week, using a conditional logistic regression adjusted on temperature, flu-like syndrome rate, pollen count, and holiday period.

Results

PM2.5 average concentration during week[-3] was significantly associated with the risk of hospitalization for MS relapse [OR = 1.21 (CI 1.01;1.46)]. The association was stronger in patients younger than 30 years [OR=1.77 (CI 1.10; 2.83)].

Conclusion

Our study demonstrates an association between exposure to PM2.5 and MS relapse, particularly in young people.