Dr. Kingsley said that the trial had some limitations, such as a smaller size and not being powered to study specific PsA subtypes, and that large doses of 20 to 25 mg a week of methotrexate may be needed for stronger results. She also said the NOR-DMARD study is limited because it is observational and does not have a control group.
Methotrexate may be effective in RA patients but not PsA patients because of different pathological processes involved, Dr. Kingsley said. “We still don’t know how methotrexate works, but we know the different things it can do chemically,” she said.
Tracking Reactive Arthritis
Rheumatologists should be ever vigilant for reactive arthritis, said John Carter, MD, associate professor of medicine at the University of South Florida in Tampa. Dr. Carter focused his presentation on reactive arthritis. Postdysentery reactive arthritis occurs in 1.5% to 30% of cases with exposure to Salmonella, Shigella, Campylobacter, and Yersinia bacteria, Dr. Carter said. There is also a postvenereal (Chlamydia-related) attack rate of about 4%.
With an estimated 3-million Chlamydia cases in the United States each year, there should be about 123,000 cases of reactive arthritis annually, just for postvenereal cases, Dr. Carter said. “When you compare [the numbers] to rheumatoid arthritis, they really should rival each other,” he said. Tracking the frequency of reactive arthritis becomes more complicated because many cases don’t present with classic symptoms. It is even likely that some cases of undifferentiated spondyloarthritis are secondary to Chlamydia, Dr. Carter said.
He discussed various treatment options for reactive arthritis. Many patients are still given NSAIDs or DMARDs. Corticosteroids can be a treatment option, “but reactive patients tend to not respond as do [patients with] some other types of inflammatory arthritis,” Dr. Carter said. There is also research into the use of antibiotics to treat reactive arthritis. Early research in this area found mostly negative results, likely because postdysentery and post-Chlamydia patients were grouped together.
Subsequent research has taken a closer look at combination antibiotic therapy, such as one study by Dr. Carter and colleagues that tested doxycycline versus doxycycline and rifampin.2 The six variables studied in the investigation, such as back pain and tender joint count, improved in the patients receiving combination therapy versus the ones receiving doxycycline only.
A more recent double-blind, placebo-controlled, prospective study by Dr. Carter and colleagues that had 42 participants randomized for treatment found that 63% of those on antibiotic combination therapy were responders versus only 20% on placebo.3 That study compared azithromycin and rifampin plus placebo instead of doxycycline; doxycycline and rifampin and placebo instead of azithromycin; and placebo only.
