Background/Purpose: Among the symptoms of Rheumatoid Arthritis (RA), pain is often regarded as a critical factor related to quality of life (QoL) by patients, and the fact of having pain confers subjects with RA a 5 year mortality twice as high when compared with RA patients without pain (1,2). There are different causes of pain in RA patients, and the level of compromise in the  QoL may vary among them too (3). The aim of this study is to identify different pain profiles in association to the QoL in Colombian RA patients.

Methods: This was a cross-sectional study involving 1395 patients with diagnosis of RA, all of whom had a registered EuroQoL, MDHAQ, CDAI and DAS-28 at the time of their involvement to a rheumatology specialized center, and a complete patient inclusion form which included data on disease characteristics, comorbid conditions and current treatment. A mixed-cluster analysis based on multivariate descriptive methods such as multiple factor analysis and k-means cluster analysis was done to summarize sets of related variables with strong associations and common clinical context. The variables used for the cluster analysis were the five dimensions of the EuroQoL, the Visual Analog Scale of the EuroQoL and the EuroQoL result (4).

Results: Four clusters were identified with varying degrees of pain and compromise on QoL (see figure 1). Due to the fact that cluster 2 was characterized by more severe pain and discomfort without severe compromise in the other dimensions, it was used as the reference group.  When compared with the patients with the least compromise of their QoL as well as pain (cluster 4) this patients were identified to be older, whit a higher proportion of females, and they had a lower education level. Regarding treatment, this patients used significantly less methotrexate, and significantly more glucocorticoids and biologic therapy. When evaluating comorbid conditions, Cluster 2 had significantly more Fibromyalgia, Cardiovascular Disease and Diabetes, and they also had a higher CDAI and DAS-28. Finally, regarding disability, we identified that cluster 2, in spite of its association with severe pain, was the one with the second best disability profile according to the MDHAQ. All the results mentioned above were statistically significant.

Conclusion: In spite of the fact that the results of a study come from a single population, they underlie the importance of identifying different pain profiles in RA patients which may benefit from specific therapies. These findings also highlight the importance of personalized medicine, which may translate into better outcomes for our patients. Figure 1. Profile of each group with respect to the original variables used to build the groups. Red bars represent the percentage of individuals in each cluster with no compromise for the given dimension, green the percentage of subjects with moderate compromise and blue the percentage of subjects with severe compromise. References: 1.           Pincus T, Castrejón I, Yazici Y. Documenting the value of care for rheumatoid arthritis, analogous to hypertension, diabetes, and hyperlipidemia: Is control of individual patient self-report measures of global estimate and physical function more valuable than laboratory tests, radiograph. J Rheumatol. 2013;40(9):1469–74. 2.           Sokka T, Pincus T. Poor physical function, pain and limited exercise: risk factors for premature mortality in the range of smoking or hypertension, identified on a simple patient self-report questionnaire for usual care. BMJ Open [Internet]. 2011;1(1):e000070. Available from: http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3191419&tool=pmcentrez&rendertype=abstract

3.           Walsh DA, McWilliams DF. Mechanisms, impact and management of pain in rheumatoid arthritis. Nat Rev Rheumatol [Internet]. 2014;10(10):581–92. Available from: http://www.nature.com/nrrheum/journal/v10/n10/full/nrrheum.2014.64.html

4.           van Reenen M, Janssen B. EQ-5D-5L User Guide – Basic information on how to use the EQ-5D-5L instrument. Version 21. 2015;(October).