Socioeconomic status trajectories across the life course, daily discrimination, and inflammation among Black and white adults.

Objective: This study replicates and expands Surachman et al.'s (2020) findings documenting socioeconomic status (SES) trajectories across the life course in an independent sample of Black (majority recruited from Milwaukee, WI) and white adults in the United States. We extend this work by examining whether SES trajectories and daily discrimination are independently associated with markers of inflammation.

Method: Data were from 215 Black adults (188 recruited from Milwaukee, WI; 27 recruited from across the continental US) and 985 white adults (7 recruited from Milwaukee, WI; 978 recruited from across the continental US) who completed the baseline interview and biomarker assessment during the second wave of the Midlife in the United States (MIDUS) Study (ages = 34-84). SES life course trajectories were examined using latent class analysis based on objective (e.g., income and education) and subjective (e.g., social status and financial strain) indicators of SES. The association between life course SES trajectories and daily discrimination with markers of inflammation (IL-6, CRP, fibrinogen) were examined using multiple linear regression analyses, controlling for demographic, psychological, behavioral, and health-related covariates.

Results: Black and white participants showed different patterns of life course SES trajectories. Among Black participants, the trajectories were Objectively Stable Low (45.16%), Downwardly Mobile (18.05%), and Upwardly Mobile (36.79%). Compared to the Upwardly Mobile, the Objectively Stable Low class showed elevated IL-6 after controlling for all covariates. Further, daily discrimination, but not SES trajectories, was significantly associated with CRP and fibrinogen after controlling for demographic, psychological, and behavioral covariates. White participants' experiences of life course SES trajectories were characterized as Objectively Stable Low (7.02%), Subjectively Downward (12.48%), Upwardly Mobile (39.99%), and Stable High (40.51%). Among white participants, SES trajectories, but not daily discrimination, were associated with all markers of inflammation (controlling for age and sex).

Discussion: Consistent with the fundamental cause theory, multiple independent pathways link SES trajectories across the life course and daily discrimination to racial disparities in IL-6, CRP, and fibrinogen.