The impact of socioeconomic status on subsequent neurological outcomes in multiple sclerosis

Abstract

BACKGROUND: To examine whether lower neighborhood-level and individual-level indicators of socioeconomic status (SES) are associated with subsequently worse neurological disability in people with MS (pwMS). METHODS: In a multi-center study using prospectively collected data from discovery cohorts (University of Pittsburgh, N=1316) and replication cohorts (Columbia University, N=488), we calculated a neighborhood SES indicator, area deprivation index (ADI), based on participants' residence at enrollment, and we derived an individual SES indicator based on participants' household income. Patient-reported neurological outcomes included the Multiple Sclerosis Rating Scale-Revised (MSRS-R), Patient-Determined Disease Steps (PDDS), and Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function scores from 2018 to 2020. We performed covariate-adjusted regression analyses in each cohort and then random-effects meta-analyses. RESULTS: Higher ADI (lower SES) in 2015 was associated with subsequently worse neurological outcomes during 2018-2020 (discovery: MSRS-R, β=0.62, 95%CI [0.36,0.89], p<0.001; PDDS, β=0.11, 95%CI [0.02,0.20], p=0.02 | replication: MSRS-R, β=0.46, 95%CI [0.21,0.72], p<0.001; PDDS, β=0.12, 95%CI [0.03,0.21], p=0.009, PROMIS, β=-0.60, 95%CI [-1.12,-0.08], p=0.025). Lower neighborhood percent with college education (MSRS-R, β=-7.31, 95%CI [-8.99,-5.64], p<0.001; PDDS, β=-1.62, 95%CI [-2.20,-1.05], p<0.001; PROMIS, β=9.31, 95%CI [5.73,12.89], p<0.001), neighborhood median household income (MSRS-R, β=-3.80e-05, 95%CI [-5.05e-05,-2.56e-05], p<0.001; PDDS, β=-8.58e-06, 95%CI [-1.28e-05,-4.32e-06], p<0.001; PROMIS, β=2.55e-05, 95%CI [5.96e-07,5.05e-05], p=0.045), and neighborhood median home value (MSRS-R, β=-6.50e-06, 95%CI [-8.16e-06,-4.84e-06], p<0.001; PDDS, β=-1.54e-06, 95%CI [-2.11e-06,-9.65e-07], p<0.001; PROMIS, β=4.98e-06, 95%CI [1.81e-06,8.14e-06], p=0.002) drove the association between higher ADI and subsequently worse neurological disability (in joint analyses). Neighborhood percent of population with Medicaid, but not private insurance, significantly mediated the observed covariate-adjusted associations. Higher individual-level household income bracket was associated with better neurological outcomes in joint analyses (MSRS-R: R=-0.39, p<0.001; PDDS: R=-0.35, p<0.001; PROMIS: R=0.37, p<0.001), independent of ADI. CONCLUSIONS: Lower neighborhood SES is associated with subsequently worse neurological outcomes in pwMS. Future testing of targeted intervention through public policies that improve SES are warranted.