Socioeconomic Status Is Protective Against Obesity, But Less So for Black Knee OA Patients

Socioeconomic status may be less protective against obesity for black patients with osteoarthritis of the knee (OA) compared to white knee OA patients, a study found.

“Although the protective effect of socioeconomic status (SES) against risk of overweight/obesity is well established, such effects may not be equal across diverse racial and ethnic groups, as suggested by the marginalization-related diminished returns (MDR) theory,” the researchers wrote. “Built on the MDR theory, this study explored racial variation in the protective effect of income against overweight/obesity of Whites and Blacks with knee osteoarthritis (OA).”

The study authors evaluated baseline data from the Osteoarthritis Initiative encompassing 4,664 adults with knee OA; 3,790 patients were white, and 874 were black. The independent and dependent variables were annual income and overweight/obesity status, defined as body mass index >25 kg/m², respectively, and the moderator was race.

A correlation was observed between higher income and a decreased likelihood of being overweight/obese. Race and income had a statistically significant relationship with overweight/obesity; however, income had a smaller protective effect for black patients compared to white patients with knee OA. Upon race-stratified regression models, the researchers observed an inverse relationship between income and overweight/obesity in white patients, but this was not observed in black patients.

The study authors concluded that while higher income may shield white patients with knee OA from overweight/obesity, the same cannot be said for black patients with knee OA; they cautioned that clinicians should be aware that high-income black knee OA patients may have different—and greater unmet—needs compared to white knee OA patients, so these two patient groups may require different treatments. They recommended that racially tailored programs be implemented to address this disparity.

“The results are important given that elimination of racial disparities in obesity is a step toward eliminating racial gap in the burden of knee OA. This is particularly important given that overweight/obesity is not only a prognostic factor for OA but also a risk factor for cardiometabolic diseases and premature mortality,” the researchers concluded.

The study was published in the August issue of the Journal of Racial and Ethnic Health Disparities.