The Effect of Comorbid Allergies on the Physical and Psychosocial Outcomes of Multiple Sclerosis Patients – a Th1/Th2 Paradigm of Autoimmune Disease
Multiple sclerosis (MS) is an autoimmune disease characterized by an abnormal response of T helper cell type 1 (Th1) against myelin self-antigen; allergies and asthma are known to be mediated by a Th2 response. Several authors have proposed that an imbalance in the response of Th1/Th2 may be associated with a decrease in the prevalence or severity of MS. This is likely an oversimplification; however, the protective effect of comorbid Th2 disease on MS has been investigated with conflicting results.
To compare the disability status assessed by Kurtzke Expanded Disability Status Scale (EDSS) score and quality of life as measured by psychosocial questionnaire (Lifeware) between MS patients with and without allergies at enrollment and after a 5-year follow up.
A retrospective matched case-control study comparing MS patients with and without allergies and/or asthma was designed using 5,096 subjects extracted from the New York State MS Consortium. Presence of allergies or asthma was determined through a self-reported questionnaire at study enrollment. The groups were matched 1:1 on sex, age, and disease duration. Chi-square tests and independent samples t-tests were used to analyze differences in measures between the two groups. A subsample of 1,310 subjects was analyzed to investigate group differences at 5 years after study enrollment.
At enrollment, the allergies/asthma group had a higher proportion of Relapsing Remitting MS (RRMS) (73.2% vs 65.6%, p<0.001) compared to subjects not reporting comorbid allergies or asthma, despite having the same disease duration (mean 10.2 [SD=9.6] vs 10.3 [SD=9.7] respectively). This difference persisted at 5 years but lost significance (p<0.07). At enrollment, the allergy/asthma group had lower EDSS scores (3.3 vs 3.6 p<0.001) but were more likely to report pain (53.8% vs 47.2% p<0.001) and overall psychosocial impairment. At 5-year follow up, the difference in EDSS scores persisted (4.0 vs 4.2 p=0.17) but was no longer significant and only the difference in perceived pain remained significant (56.5% vs 48.2% p=0.003).
We observed a small but significant association between reporting comorbid allergies/asthma and a higher number of RRMS after 10 years and a trend after 15 years of disease duration, lower EDSS scores and a stronger association with psychosocial impairment at enrollment. More studies are required to examine the role of Th2 co-morbid disorders associated with MS for more individualized appropriate therapies.