Whether patients with rheumatoid arthritis receive appropriate antirheumatic medications varies widely and depends on their age, sex, race, income, the neighborhood and area of the country where they reside, and their health care plan, according to a study in the Feb. 2 issue of JAMA.
"Although RA was once an inevitably deforming and disabling condition, the development of new DMARDs [disease-modifying antirheumatic drugs] and support for their early use has dramatically improved clinical outcomes for many patients. This study suggests that one mechanism for the sociodemographic disparities in RA outcomes in the United States may relate to differences in DMARD receipt," wrote Dr. Gabriela Schmajuk of Stanford (Calif.) University and her associates.
Recent population-based studies have shown consistently low rates of DMARD use, even though evidence-based guidelines recommend early and aggressive treatment. Dr. Schmajuk and her colleagues assessed medication use in a cohort of 93,143 RA patients enrolled in Medicare managed care plans during a recent 4-year period; the cohort comprises a nationally representative sample of the managed care population aged 65 years and older.
Overall, 37% of patients were not receiving DMARDs. These include abatacept, adalimumab, anakinra, azathioprine, cyclophosphamide, cyclosporine, etanercept, gold, hydroxychloroquine, infliximab, leflunomide, methotrexate, minocycline, penicillamine, rituximab, staphylococcal protein A, and sulfasalazine.
In some cases, patients may have declined DMARD treatment, may have had quiescent disease that didn't require treatment, or may have had contraindications to all 17 of these drugs.
The greatest variation in the rate of DMARD use occurred by patient age: Only 42% of patients aged 85 years or older received DMARDs, compared with 72% of those aged 65-69 years. While it is possible that older patients had more comorbidities limiting their ability to use these drugs, it also is possible that age bias played a role in this result, the investigators said.
Men had slightly lower rates of use than women, and patients self-identified as black or "other" had lower rates of use (57% and 58%, respectively) than white patients (64%).
The rate of DMARD use was 55% among patients with a low personal income, compared with 64% among those with higher incomes. Similarly, patients who lived in neighborhoods of low socioeconomic status were less likely to be taking DMARDs than patients living in neighborhoods with higher socioeconomic status. It is possible that some of these patients don’t get DMARDs because they are unable to afford copayments or other forms of cost sharing, the investigators said.
Patients living in the South Atlantic and Middle Atlantic regions of the country had rates of use that were 10% lower than those living in other regions.
The use of DMARDs was 6% lower among patients enrolled in for-profit health plans than among those enrolled in not-for-profit plans, a difference that was small but statistically significant.
However, variability by health plan was much greater than that statistic alone would convey. Rates of use of DMARDs varied from a low of 16% in one health plan to a high of 87% in another, even after the data had been adjusted to account for differences in case mix. This finding is "concerning," Dr. Schmajuk and her associates said (JAMA 2011;305:480-86).
It is unknown whether this 70-point difference is due to differences in the availability or accessibility of specialty care within some health plans or differences in allowances on prescription drug benefits between health plans. It may even reflect in part inaccurate reporting on the forms used to collect the data, they added.
Whatever the explanations, the large variations in DMARD use are "unacceptable," the researchers said.
"Targeting educational and quality improvement interventions to patients who are underusing DMARDs and their clinicians will be important to eliminate these disparities," they said.
This study was supported by the American College of Rheumatology, National Center for Research Resources, Rosalind Russell Medical Research Centers for Arthritis, National Institutes of Health, State of California Lupus Fund, Arthritis Foundation, Agency for Healthcare Research and Quality, and National Institute of Arthritis and Musculoskeletal and Skin Diseases. An associate of Dr. Schmajuk reported financial ties to Merck and the Pfizer Foundation.