The Relationship Between Socioeconomic Status and Disability in MS Is Linked to Diet
Ilana Katz Sand1, Kathryn Fitzgerald2, Sammita Satyanarayan3, Michelle Fabian4, James Sumowski5
1Corinne Goldsmith Dickinson Center for MS, 2Johns Hopkins University, 3Mount Sinai Medical Center, 4Mount Sinai Hospital, 5Icahn School of Medicine At Mount Sinai
Objective:
Evaluate whether the association between socioeconomic status (SES) and disability in multiple sclerosis (MS) is mediated by diet.
Background:
A recent publication concluded lifestyle factors (e.g., smoking, alcohol, BMI) help explain the link between SES and incident MS. Lower SES is also associated with worse MS disability. Investigators hypothesize a role for modifiable lifestyle factors in explaining this association; here we evaluated the contribution of diet.
Design/Methods:
Persons with MS (n=563; 71% women; aged 44.2±11.3 years) completed the MS Functional Composite (MSFC) to assess MS-related disability. An SES index was derived from educational attainment (self/parental), literacy, and neighborhood deprivation (AHRQ formula utilizing zip code socioeconomic indicators). Participants completed the Mediterranean Diet Adherence Screener (MEDAS) to assess diet. After confirming intercorrelations among SES, MEDAS, and MEDAS, the PROCESS macro for SPSS (version 4.2, model 4) tested whether MEDAS mediates the relationship between SES and MSFC, first with variables adjusted for demographics (age, sex, race/ethnicity), then additionally adjusted for health factors (BMI, exercise, sleep disturbance, histories of smoking, diabetes, hypertension, hyperlipidemia).
Results:
Adjusting for demographics, MSFC correlated with SES (r=0.28) and MEDAS (r=0.26), and SES correlated with MEDAS (r=0.23, Ps<0.001). Mediation analysis: MEDAS partially mediated the link between SES and MSFC; MEDAS explained 18.8% of that relationship (meditation: 0.003 [0.001, 0.004]; total: 0.016 [0.011, 0.020]; direct: 0.013 [0.009, 0.017]). Additionally adjusting for relevant health factors, MSFC still correlated with SES (r=0.27) and MEDAS (r=0.24), and SES correlated with MEDAS (r=0.19, Ps<0.001). MEDAS continued to partially mediate the link between SES and MSFC, explaining 13.3% of that relationship (mediation: 0.002 [0.001, 0.003]; total: 0.015 [0.011, 0.020]); direct: 0.013 [0.009, 0.018].
Conclusions:
The relationship between SES and MS-related disability is partially explained by dietary habits, highlighting the particular need for healthcare initiatives focused on modifiable lifestyle factors that are available and accessible to those from socially disadvantaged backgrounds.