Study ties socioeconomic status to AS disease severity, disability
Differences remain despite access to DMARDs
Lower socioeconomic status is associated with more severe disease, longer diagnosis delays, and permanent disability in people with ankylosing spondylitis (AS), a Spanish study showed.
Even with similar access to disease-modifying anti-rheumatic drugs (DMARDs), socioeconomic status may be a significant factor for understanding health outcomes differences between AS patients, the scientists suggested.
The study, “The socioeconomic status of patients with ankylosing spondylitis and its association with the burden of the disease and permanent disability: a cross-sectional cluster analysis” was published in Therapeutic Advances in Musculoskeletal Disease.
AS is a type of arthritis that primarily affects the spine’s joints. As the disease progresses, mobility, quality of life, psychological status, and work productivity may deteriorate. The sooner a patient receives diagnosis and treatment, the more effectively the disease can be controlled.
Studies have shown that physical functioning and structural damage to the body are associated with work disability in AS. However, “no studies have been conducted to examine the socioeconomic profile of patients with a greater probability of permanent disability,” the researchers wrote.
Spanish registry keeps tabs on patients
In Spain, DMARDs are free of charge, regardless of patient income or employment status, making the Spanish Registry of Spondyloarthritis, or REGISPONSER, “an excellent registry for evaluating different socioeconomic profiles of patients with AS and their associations with disease severity and permanent disability,” the team wrote.
The study analyzed 866 AS patients treated in 21 Spanish hospitals between March 2004 and March 2007. Most of the patients were male (74.7%), and their mean age was 48.4.
After a statistical analysis considering different demographical and socioeconomic variables, two clusters emerged based on socioeconomic status (SES): 476 patients were grouped as low SES and 390 as high SES.
Most low SES patients (91.6%) were classified as lower middle class or “underclass,” while nearly all high SES patients (99.5%) fell into the upper, upper middle, or middle class, according to the study. There were more married people among low SES patients (81.5%) than in the high SES group (71%). Some 73.1% of high SES patients reported university education, compared with 4.4% in the low SES group.
Almost half of the low SES group were unemployed or housekeepers (48.9%), whereas 67.4% of the high SES group were employed or retired. Nearly three-quarters (72.1%) of the low SES group lived in housing conditions described as good, deficient, or inadequate. In comparison, “luxury/optimal” described the housing of about two-thirds (65.9%) of high SES patients.
Low SES patients, with a mean age of 51.6, were significantly older than high SES patients, who were about 44.5. Mean age at diagnosis was 37 for the low-SES group and 32.7 for high SES patients. Body mass index, a measure of body fat, was significantly higher in low SES patients (27.6 vs 25.9), who also had longer disease duration (14.6 years vs 11.6 years).
The low SES group had a mean diagnosis delay of 7.8 years, longer than the 6.8 years reported for high SES patients. The percentage of those who had smoked was also higher in low SES participants (34.4% vs. 26.4%).
Mental health, disease activity
The mental health component of SF-12 and the Bath axial spondylitis radiology index, which evaluates structural damage to bone, indicated poorer mental health and worse disease activity in the low SES group when compared to the high SES patients.
The prevalence of permanent disability among all patients in the study was 23.1%. However, permanent disability was significantly more common in low than in high SES patients (30.8% vs. 13.2%). Low SES participants were 2.4 times more likely to be in permanent disability when considering disease duration, diagnosis delay, and disease activity.
“Socioeconomic status may independently influence the severity of the disease and work participation,” as access to DMARDs was similar for both groups, the researchers wrote.
Low SES patients and those with manual jobs are more likely to receive a chronic pain diagnosis, delaying their AS diagnosis, the study found. “Considering the greater structural damage, greater prevalence of obesity and greater frequency of ‘blue collar’ jobs in [the low SES group], we can establish the assumption that patients in [that group] are unable to continue their jobs after several years of having the disease,” the scientists wrote.
They also noted that, according to previous research, low education levels and unemployment are linked to unfavorable therapy self-management and less knowledge about AS.
The study design does not allow for the direct establishment of SES as the cause of disability, and disease severity criteria were limited to those used in the mid-2000s, the researchers noted. However, “several associations were demonstrated, which can be confirmed through future prospective studies,” they added.
About the Author
