medwireNews: Study findings suggest that approximately one-third of patients with rheumatoid arthritis (RA) have long-term unacceptable pain, despite control of inflammation in the majority of these people.
“This points to substantial unmet needs regarding pain management beyond anti-rheumatic treatment and highlights the importance of improved management of these patients,” say Anna Eberhard (Lund University, Malmö, Sweden) and co-authors.
The researchers evaluated pain outcomes in 232 people with early RA (median symptom duration 7 months) who attended a rheumatology clinic at Malmö University Hospital in 1995–2005. A total of 179 participants remained in the study for 5 years of follow-up.
As reported in Arthritis Research & Therapy, average VAS pain score decreased significantly from 41.2 mm at baseline to 32.3 mm at the 6-month follow-up, but then “remained more or less unchanged” for the rest of the 5-year follow-up period.
Accordingly, the proportion of individuals with unacceptable pain – defined as VAS pain score of more than 40 mm based on the patient acceptable symptom state – was 49.1% at baseline and decreased to 30.1% after 1 year, but remained consistent for the remainder of the study.
Eberhard and team note that the majority of people with long-lasting unacceptable pain had low levels of inflammation. For instance, at the 5-year follow-up, 34% of the cohort had unacceptable pain, and approximately 23% had unacceptable pain and C-reactive protein levels below 10 mg/L.
The study authors also carried out a multivariate analysis to identify predictors of unacceptable pain, finding that women had a 2.57-fold increased risk at 2 years compared with men, while each standard deviation increase in VAS pain at baseline was associated with a 1.56-fold increased risk at this timepoint. Women did not have a significantly increased risk for unacceptable pain at 5 years, but higher baseline VAS patient global assessment, along with lower baseline swollen joint count (SJC) – indicating less inflammatory disease – were significant predictors.
The association between lower baseline SJC and unacceptable pain at 5 years “may be explained by the positive effects of treatment on pain related to inflammation,” write Eberhard and colleagues. They note that low baseline inflammatory parameters and anti-cyclic citrullinated peptide negativity were predictors of unacceptable pain with low inflammation.
“These results all indicate that pain in RA is multifactorial and might include central pain mechanisms, encompassing an increased risk of secondary fibromyalgia and persistent nociplastic pain, presumably sharing common mechanisms of disease development, such as central sensitisation,” say the investigators.
They add: “Health care workers should be aware of the uncoupling between pain and inflammation, and in cases of severe pain despite inflammation control consider initiation of targeted multimodal pain interventions.”
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