OBJECTIVE

The study objective was to identify subgroups of patients with rheumatoid arthritis (RA) based on their health status 3 years after diagnosis and to assess potential associations to clinical presentation at diagnosis.

METHODS

This observational study included patients with RA with 3-year follow-up data from the Swedish Epidemiological Investigation of RA study, collected from 2011 to 2018. Hierarchical agglomerative cluster analysis, based on symptoms of pain, fatigue, sleep quality, mood disturbances, and overall health-related quality of life (HRQoL), was used to identify subgroups 3 years after diagnosis. Modified Poisson regression was used to estimate risk ratios (RRs) and 95% confidence intervals (CIs) for the associations between the subgroups and patient characteristics at diagnosis.

RESULTS

A total of 1055 individuals constituted the study population, of whom 1011 had complete data on the clustering variables and were therefore eligible for analysis (73% women, median age 58 years). The following three clusters were identified: cluster 1 (466 patients with good health status), cluster 2 (398 patients in an intermediate group), and cluster 3 (147 patients with high levels of pain and fatigue together with markedly impaired HRQoL). Cluster 3 was associated to higher baseline pain (RR: 3.71 [95% CI: 2.14-6.41]), global health (RR: 6.60 [95% CI: 3.53-12.33]), and the Stanford Health Assessment Questionnaire (RR: 4.40 [95% CI: 2.46-7.87]), compared with cluster 1 (highest compared with lowest quartiles). An inverse association was seen for baseline swollen joint count (RR: 0.51 [95% CI: 0.34-0.85]).

CONCLUSION

A subgroup of patients with RA experience high levels of pain, fatigue, and psychosocial distress 3 years after diagnosis. This subgroup already displayed pronounced pain and functional disabilities at diagnosis.