Dr. Rubin applauds the British study because he says it tried to answer a difficult clinical question – but he notes that the study has flaws. He says one of the major problems is that it “took all-comers” with psoriatic arthritis when in fact the disease is highly variable. “There are very different subsets of psoriatic arthritis. Some have just a few joints involved, some have disease resembling something like rheumatoid arthritis,” he says. Dr. Rubin has found methotrexate does provide symptomatic relief to some of his patients with multiple joint involvement and psoriasis.

Eric Matteson, MD, chair of rheumatology at the Mayo Clinic in Rochester, Minn, says he has had similar experiences. “In my view and experience, methotrexate does work for individual patients with peripheral joint disease, especially in the hands and feet,” he says.

The study results mirror that of another, similar – though much smaller – trial involving methotrexate and placebo from nearly 30 years ago. Thirty-seven patients participated in that 1984 study, which was published in Arthritis & Rheumatism. It found improved physician assessments of arthritis (and in the amount of skin surface affected by psoriasis) but nothing else.

As for this study, Dr. Rubin asks, “Is it going to change most clinically practicing rheumatologists treatment of people with psoriatic arthritis? No. Is it intriguing? Yes. Does it mean there may be better drugs for the disease? Probably yes.”

Dr. Matteson agrees. “I do think that anti-TNF [tumor necrosis factor] agents are the best choice especially for patients with multiple involved joints,” Dr. Matteson says, referring to biologic agents such as etanercept, or Enbrel, infliximab, or Remicade, and adalimumab, or Humira. “[But] it is important to recognize that psoriatic arthritis is a spectrum of very mild to very severe disease, and that there are patients who do not require biologics for management of their disease.”

It’s also important to note, as the study authors did, that British medical authorities recommend using methotrexate before moving on to more expensive, anti-TNF therapies. In the United States, the American College of Rheumatology recommends that treatment of PsA be related to the severity of the condition and the level of pain. Nonsteroidal anti-inflammatory drugs, such as ibuprofen or naproxen; traditional disease-modifying antirheumatic drugs including methotrexate, leflunomide and sulfasalazine; and anti-TNFs are all deemed appropriate.

Dr. Rubin suspects that, given the length of time it took to set up the study, the researchers may have had some trouble recruiting patients for ethical reasons. “This was an almost 10-year project for a six-month study,” Rubin says. “There are a lot of physicians who probably said, ‘I don’t know whether it’s ethical to put a patient with psoriatic arthritis on placebo for six months.’”