Background/Purpose: Measures of socioeconomic status (SES) have been shown to be associated with increased OA and disability. However, it is unknown whether changes in SES measures over time can predict death. We therefore examined whether SES measured over time was associated with death among those with radiographic OA (rOA).

Methods:   We analyzed data from 2,605 participants in a community-based cohort of African American (AA) and Caucasian men and women aged ≥45 years. Participants completed assessments at baseline and up to 3 follow-ups and all had rOA, defined as Kellgren-Lawrence grade ≥2 in at least one knee/hip. SES measures were 1) high school (HS) education (<HS diploma vs. ≥HS diploma), 2) professional occupation (PRO) (non-PRO vs. PRO, and 3) block group poverty (BGP) (≥20% BGP vs. <20% BGP). Date of death was assessed through December 31, 2015. Comorbidities and demographic characteristics were considered as covariates (see Table legend). Multiple imputation was used to impute missing values of covariates. Follow-up time was calculated from baseline until death or censoring which took place when a participant was lost to follow-up or reached the end of study period.

Cox proportional hazards regression with time-varying covariates (TVC) changing at irregular intervals was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for all-cause mortality. In the TVC analysis, SES and covariates were allowed to change from “unexposed” to “exposed” from prior assessments to ensure HRs accurately represent the risk of mortality as one’s SES and covariate status changed. Additional analyses stratified by sex, race and age were carried out.

Results: Mean age at baseline was 65.4 years, with 64.0% women and 34.1% AA. Overall, 37.7% had <HS education, 41.3% lived in areas with ≥20% BGP, and 61.0% had a non-PRO occupation. Through 2015 there were 1,154 deaths (44.0%), and median follow-up time was 10.2 years.

In covariate adjusted models where individual SES measures were considered, we observed an increased risk of all-cause mortality in participants with <HS education (HR=1.30, 95% CI=1.15-1.48) and non-PRO occupation (HR=1.21, 95% CI=1.06-1.39) (Table). However, when all SES measures were considered simultaneously, only <HS education remained associated with death (HR=1.25, 95% CI=1.09-1.43).  In stratified analyses, the observed association with education was restricted to women. Living in an area with high BGP appeared to be a predictor of mortality among Caucasians only.

Conclusion: As noted in other chronic conditions, we demonstrated increased mortality among individuals with knee or hip OA with low education, particularly among women. Our results were independent of other comorbidities and demographic measures linked to increased mortality. Individuals with OA and lower education may represent a high risk group in need of more focused clinical care and resource allocation.