In patients with rheumatoid arthritis (RA), knowing the features of progressive hand deformity may permit rheumatologist to more easily implement practical interventions and establish functional prognosis, thus providing them with a clearer understanding of impaired activities of daily living experienced by these patients. Findings from a cohort study of patients with RA and hand deformities were published in the journal Arthritis Research & Therapy.

Recognizing the challenges in treating patients with RA whose hands have 3 major deformities—thumb deformities, finger deformities, and ulnar drift­—the researchers sought to determine a simple composite method for understanding the alterations in and pathophysiology of hand deformities among these individuals. In 2004, they established a rheumatoid hand cohort, in which a total of 134 hands in 67 patients were evaluated. The assessments were repeated in 2009, this time in 100 hands in 52 patients, and again in 2015 in 63 hands in 37 patients.

Hand deformities were evaluated at each visit, as well as functional assessments. Pharmacologic therapies were prescribed to all participants in accordance with European League Against Rheumatism and American College of Rheumatology guidelines/recommendations. Thumb deformities, finger deformities (ie, swan neck and boutonnière), and ulnar drift were entered as parameters for the 2004 data.

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Results of the study demonstrated that 5 clusters most appropriately defined hand deformity, with the features of each of the clusters as follows: cluster 1: minimal deformity (ie, minimal finger deformities, and ulnar drift without thumb deformity);

 cluster 2: thumb type 1 deformity (ie, type 1 thumb deformity and minimal finger deformities with ulnar drift); cluster 3: thumb and boutonnière deformity (ie, type 1 or 6 thumb deformity and severe boutonnière deformity with ulnar drift); cluster 4: thumb type 2 or 3 and ulnar drift deformity (ie, type 2 or 3 thumb deformity with severe ulnar drift); and cluster 5: thumb deformity and severe swan-neck deformity (ie, various types of thumb deformity and severe swan-neck deformity with ulnar drift).

Patients in clusters 1 and 2 had higher function than did those in cluster 5; participants in cluster 3 exhibited moderate function. In addition, participants in clusters 1 through 4 reported similar durations of disease but different paths of deformity progression from onset of RA. Findings showed that clusters 1 and 2 exemplified conservative deformity parameters, whereas clusters 3, 4, and 5 represented progressive deformity parameters. With time, thumb deformities evolved into other types of hand deformities. Further, swan-neck deformity worsened significantly.

Multiple comparisons were conducted, with a significant main effect of cluster (P < .001) and evaluation point (P <.001) reported. Cluster 5 differed significantly from all of the other clusters. Significant differences were observed from 2004 to 2015, as well as from 2009 to 2015. A significant main effect of the cluster was observed for the boutonnière score (P < .001).

A major limitation of the study is that the investigators were unable to demonstrate how deformities developed in each subset of participants, as the cohorts were not followed from the onset of developing RA.

The researchers concluded that this comprehensive evaluation of rheumatoid hand features could serve as a useful tool for rheumatologists and other clinicians, to better understand the needs and symptoms of their individual patients.


Toyama S, Tokunaga D, Tsuchida S, et al. Comprehensive assessment of alterations in hand deformities over 11 years in patients with rheumatoid arthritis using cluster analysis and analysis of covariance. Arthritis Res Ther. 2021;23(1):66. doi:10.1186/s13075-021-02448-4