Socioeconomic Status Impairs Patients with Rheumatoid Arthritis

Research from the University of California observed that patients with rheumatoid arthritis with a lower socioeconomic status (SES) had worse functional status (FS) and faster declines in functioning over time.

A cohort study was conducted due to the lack of information on the association of poverty with functional status in patients with RA who use rheumatology care. What little information that existed on the subject was culled from single-center studies, which Patricia Katz, MD, and colleagues felt were limited.

The investigators utilized a national, EHR-enabled registry that passively collected data on all patients seen by participating practices to examine the association between SES and functional status among individuals with RA across the United States and the implications over time.

The Study

Katz and colleagues used the American College of Rheumatology’s Rheumatology Informatics System for Effectiveness (RISE) to collect data from 1113 clinicians in 226 practices that represented approximately 32% of the US clinical rheumatology workforce.

A total of 83,965 patients with RA were included in the cross-sectional analysis.

Patients were aged 18 years or older and had at least 2 visits with RA International Classification of Diseases, Ninth Revision and Tenth Revision codes that were at least 30 days apart, with and 1 FS measure documented between January 1, 2016, and December 31, 2018.

The investigators used the Area Deprivation Index (ADI) as a proxy for patient’s SES, which incorporated neighborhood income, education, employment, and housing quality domains.

From there, they incorporated functional status measures such as the Health Assessment Questionnaire Disability index (HAQ),Health Assessment Questionnaire–II (HAQ-II),and Multidimensional Health Assessment Questionnaire (MDHAQ).

Finally, cross sectional and longitudinal analyses were conducted to assess the association between SES and functional status and functional decline over time. The association was then evaluated based on disease activity among a subgroup of participants for whom Clinical Disease Activity Index (CDAI) scores were available.

Results

Though age and sex distributions were comparable across ADI quintiles in both the cross-sectional and longitudinal cohorts, the racial/ethnic distribution varied significantly across SES levels in both cohorts.

A higher proportion of non-Hispanic White and Asian patients in the first ADI quintile were recorded compared to the fifth quintile, and more African American and Hispanic patients in the fifth ADI quintile compared with the first quintile.

A total of 35,385 patients were included in the pooled adjusted longitudinal analysis, with the data indicating that functional decline was higher at higher ADI quintiles.

The MDHAQ was the most reported functional status measure, representing 68% of the total study population, followed by HAQ (24%) and HAQ-II (8%). In all 3 measures, the mean functional status score was higher at higher ADI quintiles, which indicated greater disability.

Katz and colleagues mentioned future investigations could improve upon the disparities referenced by understanding the reasons for higher disease activity among patients in lower SES groups and managing delays in diagnosis and treatment

The team recommended continued research on the subject.

“We provide a framework for monitoring disparities in RA in rheumatology practices,” the team wrote. “Future qualitative research is important to further our understanding of factors that affect FS, including factors outside of medical care that can be intervened on.”

The study, "Socioeconomic Disparities in Functional Status in a National Sample of Patients With Rheumatoid Arthritis," was published online in JAMA Open Network.