Background: While clinical relapses are the defining feature of relapsing-remitting multiple sclerosis (RRMS), their characteristics vary widely from patient to patient. We sought to identify predictors of MS relapse location. Based on current literature, two potential predictors were identified: treatment with interferon beta (IFNB), and location of previous relapse.
Methods: RRMS patients were identified from the UCSF MS Center database who underwent at least 3 months of IFNB or glatiramer acetate (GA) treatment. The relapse immediately preceding the initiation of treatment (pre-treatment relapse), and the first relapse occurring after the initiation of treatment (on-treatment relapse) were coded as affecting the spinal cord (SC), optic nerve (ON), brainstem/cerebellum (BC), or cerebrum. Logistic regression was performed to identify independent predictors of on-treatment relapse location.
Results: The 134 IFNB and 56 GA patients did not differ in gender, race, age at symptom onset (30.3 years), or disease duration at treatment start (5.7 years). Patients with pre-treatment SC relapses had increased odds of having on-treatment SC compared to non-SC relapses (OR=2.31, p=0.013); the same tendency for localization occurred with BC (OR=3.05, p=0.013), and ON relapses (OR=3.63, p=0.011). Additionally, patients who relapsed on treatment had a higher SC (but not ON or BC) relapse risk when they were on IFNB compared to GA (OR 2.05, p=0.041), independent of pre-treatment relapse location.
Conclusion: Our results show a tendency for patients to have localized exacerbations, which could be mediated by genetic or immunological factors. In addition, and to be confirmed in subsequent studies, IFNB treatment may influence SC relapse risk.
- multiple sclerosis
- optic nerve
- spinal cord