MADRID – A considerable number of patients with psoriatic arthritis starting their first biologic treatment report unacceptable pain throughout the first year of treatment, even when their inflammation is controlled, according to Swedish researchers.
Mitchel L. Zoler/MDedge News
Dr. Tor Olofsson
“Despite this often efficient therapy, 40% of patients still had unacceptable pain after 1 year, and pain with features indicative of a noninflammatory mechanism accounted for more than 60% of this pain load,” senior study author Tor Olofsson, MD, a rheumatologist and doctoral student at Lund (Sweden) University, said in an interview in advance of his presentation at the European Congress of Rheumatology.
“Within rheumatology, today we are generally very good at treating inflammation in many of the arthritides, but we have a lot of patients with persistent pain despite being well treated for their inflammation,” Dr. Olofsson said. “In psoriatic arthritis patients, this remaining pain seems to be even more frequent than in rheumatoid arthritis with the capturing instruments we use here.”
Dr. Olofsson and his colleagues studied prospectively collected records from 352 psoriatic arthritis patients (48% women) participating in the South Swedish Arthritis Group register who started a first anti–tumor necrosis factor (anti-TNF) therapy during 2004-2010. Participants had a mean age of 47 years and a mean disease duration of 10 years. At the start of anti-TNF therapy, 63% of patients were taking methotrexate, and 68% were taking any conventional disease-modifying antirheumatic drug (DMARD).
Based on the Patient Acceptable Symptom State, unacceptable pain was defined as greater than 40 mm on a 0-100 mm Visual Analog Scale (VAS). Inflammation control was captured through C-reactive protein level less than 10 mg/L in combination with one or no swollen joints. Assessments were performed at baseline, 1.5, 3, 6, and 12 months after the start of the first anti-TNF agent. Analyses were also conducted in relation to European League Against Rheumatism (EULAR)–defined treatment response after 3 months (good, moderate, or no response).
At the start of anti-TNF therapy, 85% of patients reported unacceptable pain, which declined to 43% after 3 months and then remained stable, reaching 39% at 12 months. The fraction of patients who had unacceptable pain despite inflammation control was largely unchanged over the study period (24% at treatment start, 27% at 3 months, and 26% at 12 months). Unacceptable pain at 3 months was strongly related to EULAR 3-month response (24% of good responders vs. 79% of nonresponders; P less than .001). This relationship was less pronounced among patients with unacceptable pain despite inflammation control (19% of good responders vs. 37% of nonresponders; P = .016). Among EULAR good responders, unacceptable pain despite inflammation control constituted 81% of all unacceptable pain at 3 months.
Dr. Olofsson said he was surprised by the high levels of pain despite inflammation control reported by these patients. A similar study he and others conducted in rheumatoid arthritis patients a year ago, soon to be published, found that only 12% had unacceptable pain despite inflammation control 1 year after start of a first anti-TNF agent, “so captured by the same instruments, it looks like this problem might be even bigger among patients with psoriatic arthritis.”
There is a possibility that psoriatic arthritis patients may have ongoing pain from low-grade inflammation, he said, but another hypothesis is that many psoriatic arthritis patients develop a more generalized pain condition in line with fibromyalgia. It could be that, if inflammation isn’t treated quickly enough in the beginning of the disease, it could sensitize the central pain system, he said, and it may not be reversible after it has developed.
Alternative treatment strategies are often needed in affected patients, Dr. Olofsson added. This could include regular painkillers or medicines used for more generalized, noninflammatory pain states, such as amitriptyline or duloxetine, as well as nonpharmacologic treatment options.
“The bottom line here is that, if patients are treated aggressively early enough, we might be able to prevent development of this sensitization process,” Dr. Olofsson said. “If we can also do predictive studies to describe which patients have a higher risk of developing this, then maybe we can be even more focused in the initial management before they become centrally sensitized.”
Dr. Olofsson had no financial conflicts to disclose. Two of his coauthors reported relationships with AbbVie, Eli Lilly, Celgene, Novartis, UCB, and Sandoz.
Mitchel L. Zoler contributed to this report.
SOURCE: Roseman C et al. Ann Rheum Dis. 2019 Jun;78(Suppl 2):129-30. Abstract OP0112, doi: 10.1136/annrheumdis-2019-eular.1839.