Some of the same factors that predict patients’ discontinuation of disease-modifying antirheumatic drugs for rheumatoid arthritis also appear to predict their initiation, such as use of oral glucocorticoids and Hispanic ethnicity, according to findings from a longitudinal cohort study.
It was "surprising" to lead investigator Dr. Daniel H. Solomon of Brigham and Women’s Hospital, Boston, and his associates that some of the same variables predicted both starting and stopping RA medication. "These factors may correlate with frequent treatment switches," they wrote. The fact that Hispanics were significantly more likely to start and to stop medication than non-Hispanics might reflect disparities in insurance coverage, differences in the availability of new treatments, or impaired communication about side effects because of language barriers, they added in their report published in Arthritis Care and Research.
Dr. Daniel H. Solomon
Dr. Solomon and his colleagues based their analysis on data from the University of California, San Francisco, RA Panel study, a longitudinal cohort of 1,507 persons with rheumatoid arthritis (RA) who were randomly sampled from rheumatology practices in Northern California (Arthritis Care Res. 2014;66:1152-8). The study used a paired-years analysis to calculate percentages of patients who were on or off RA medications for a year and then either stopped or started medication the next year, the investigators said.
Of 1,974 pairs of years in which people were not on RA medication in year 1, they started medication the next year in 313 (15.9%) of the pairs. And of 7,595 pairs of years in which patients were taking medication in year 1, patients stopped all RA medications the next year in 423 (5.6%) of the pairs, the researchers reported.
In regression analyses, subjects were more likely to start medication when they were younger (odds ratio, 1.30; 95% confidence interval, 1.13-1.50/10-year decrease), Hispanic (OR, 1.88; 95% CI, 1.06-3.33), had RA for a shorter time (OR, 1.11; 95% CI, 1.01-1.22/5-year decrease), or were taking oral glucocorticoids (OR, 1.91; 95% CI, 1.36-2.67), the researchers said. Predictors of stopping RA drugs also included being younger (OR, 0.88; 95% CI, 0.80-0.98/decade decrease) or Hispanic (OR, 1.52; 95% CI, 1.02-2.30) and having the lowest annual income, compared with the highest income (OR, 1.83; 95% CI, 1.13-2.96), according to Dr. Solomon and his associates.
The "noteworthy" drop in RA drug discontinuation during the 23-year course of the study from 9% in 1986 to 3% in 2008 "may correlate with the increasing range of treatment options since the latter half of the 1990s. It may also be that rheumatologists have become less concerned about slightly abnormal laboratory results that occur occasionally by chance, for example, liver function tests among methotrexate users," the investigators suggested.
In contrast, no strong trends could be found for starting disease-modifying antirheumatic drugs during the study period.
"As health systems currently evolve with Medicaid expansions and a greater emphasis on primary care, reducing these barriers to appropriate care for patients with rheumatic disease will be an important goal," they concluded.
The study was funded by grants from the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Some of the investigators reported receiving financial support from Amgen, the Consortium of Rheumatology Researchers of North America, Eli Lilly, and Pfizer.