LONDON, United Kingdom — Smoking and obesity have again been implicated as key predictors of poor response to treatment in patients with early rheumatoid arthritis, especially women, new research shows.
"Patients come in all the time and ask, 'What can I do differently? How can I get back to being normal?'" investigator Susan Bartlett, PhD, associate professor of medicine at McGill University in Montreal, said during a news conference here at the European League Against Rheumatism Congress 2016.
"First of all, they need to take their medication and get the disease under control," she said.
"But the second thing is that patients must stop smoking if they smoke, especially if they are female. The same goes for weight. If patients are overweight, they are overloading their joints, but being obese also affects the way medications work. They just don't work as well in heavier people or in people who smoke," she explained.
With this study, "I've got a clear message that I can give my patients when they ask what they can do: They can stop smoking and lose weight," Dr Bartlett said.
The study relied on data from the Canadian Early Arthritis Cohort (CATCH), a multicenter prospective cohort study in which more than 1000 patients with a rheumatoid arthritis duration of less than 12 months were evaluated.
A patient with a body mass index (BMI) from 18.5 to 24.9 kg/m² was considered healthy, from 25.0 to 29.9 kg/m² was considered overweight, and 30.0 kg/m² or higher was considered obese.
"About one-third of the group was obese; this was true for both men and women. These are higher rates than you would expect in the general population," Dr Bartlett pointed out.
More men than women in the cohort were overweight (47% vs 30%).
"Patients were getting really great treatment when they were diagnosed," Dr Bartlett reported. Almost three-quarters of the patients were taking methotrexate after their initial diagnosis, and more than half were taking steroids.
Sustained remission was defined as a disease activity score in 28 joints (DAS28) below 2.6 on two consecutive visits.
"The proportion of sustained remission rates rose steadily," said Dr Bartlett. At 3 years, 38% of the overall cohort met the criteria for sustained remission.
Median time to sustained remission in the overall cohort was 11.3 months.
On a Cox survival analysis, BMI class was shown to be significantly associated with sustained remission (P = .003), as were smoking (P = .046) and sex (P = .02).
On the basis of these results, the researchers calculated probabilities of sustained remission for a "prototypical" patient: 53 years of age, white, some postsecondary education, symptom duration of 5 months, two comorbidities, and a DAS28 of 5. In addition, the prototypical patient would be taking both methotrexate and steroids.
Using these criteria, the probability of sustained remission 3 years after the initiation of treatment is 10% for an obese woman who smokes. In contrast, the probability for a nonsmoking woman with a healthy body mass index (BMI) is 27%.
For an obese man who smokes, the probability of sustained remission at 3 years is 15%, whereas for a nonsmoking man with a healthy BMI, it is 41%.
"Stopping smoking and losing weight are tough behaviors for patients to change," Dr Bartlett acknowledged. "But I think understanding that smoking and obesity really can make a difference, not only in how you feel, but also in how your medications will work, may motivate patients."
"People are very concerned about how much medication they need to take, so anything we can do to help them reduce the amount of medication or the number of medications they need to take is important to communicate," she told Medscape Medical News.
Poor Response to Methotrexate
In a separate study of a long list of lifestyle, clinical, and psychosocial predictors, BMI and smoking at baseline were significant predictors of nonresponse to methotrexate 6 months after treatment initiation.
In the final predictive model, smoking was associated with an almost 60% greater risk for a poor response to methotrexate, report Suzanne Verstappen, PhD, from the University of Manchester in the United Kingdom, and her colleagues.
A higher BMI was associated with a much smaller likelihood of a poor response to methotrexate, although it was still significant.
"Being able to predict which of our rheumatoid arthritis patients are likely to not respond to methotrexate would enable us to provide earlier access to alternative drugs, with the hope of avoiding disease progression," Dr Verstappen said in a statement.
It is important that the public be aware that they should stop smoking and lose weight if they have rheumatoid arthritis, said João Fonseca, MD, PhD, from the Instituto de Medicina Molecular in Lisbon, Portugal.
"If you are a healthy person but you smoke and are obese, you are at greater risk for rheumatoid arthritis," he added.
Dr Bartlett said she agrees, adding that people are probably unaware that smoking and obesity are strong risk factors for the development of rheumatoid arthritis.
"If there is a history of rheumatoid arthritis in your family and you smoke, you are pouring gasoline on a dangerous situation," she said. "The fact that weight is a risk factor for rheumatoid arthritis is relatively new."
"I'm not suggesting that smoking and weight are easy to change, but changing them will make a difference," Dr Bartlett said. Patients will have much better control of their disease "if they reduce these two risk factors quickly."
Dr Bartlett and Dr Verstappen have disclosed no relevant financial relationships.
European League Against Rheumatism (EULAR) Congress 2016: Abstract OP0173 presented June 10, 2016; Abstract OP0013, presented June 8, 2016.
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Cite this: Smoking, Weight Gain Barriers to Remission in Early RA - Medscape - Jun 11, 2016.