Background/Purpose: Sarcoidosis is a disease with heterogeneous clinical presentation and course. The objective of this study is the identification of clinical phenotypes using cluster analysis.

Methods: A model-based clustering relaying on 19 clinical variables was performed in a retrospective cohort of 342 sarcoidosis patients, diagnosed and follow-up from 1999 to 2019 in a hospital at Northern Spain. Chi-square test and ANOVA were used to compare categorical and continuous variables among groups. Two-sample t-tests and the partition of Pearson’s chi-square statistic were used in pairwise comparisons. The Wasfi severity score was calculated and compared among clusters.

Results: Cluster analysis identified five groups: C1: erythema nodosum and articular involvement (n=55; 16.1%), C2: miscellaneous extrapulmonary sarcoidosis (n=49; 14.3%), C3: ocular and/or neurological involvement (n=83; 24.3%), C4: isolated hiliar adenopathy (n=17; 5.0%), and C5: parenchymal lung involvement with dyspnea (n=138; 40.4%). Lung involvement was predominant in all clusters, ranging from 89.9% (C5) to 100% (C1 and C4), except for C2 (55.1%). Extrapulmonary involvement was significantly higher in C2 (96.4%) and C3 (98.0%). Demographic and clinical characteristics are shown in Table 1. A significant low mean FEV1 was detected in C5 (90.5±21.8) versus C1 (102.0±22.9), C3 (102.3±17.6) and C4 (105.8±20.8). The cluster 5 had a significantly lower mean FVC (96.6±18.9) than the other clusters, ranging from 108.1±18.0 (C3) to 111.5±21.7 (C4). The prescription of systemic steroids and non-corticosteroid immunosuppressants was significantly higher in the clusters 1, 3 and 5. Chronicity rates were significantly higher in C3 (31.3%) and C5 (32.6%) compared to C1 (9.1%) and C4 (0%). The clusters 3 and 5 also showed significantly higher severity score values. According to the clusters identified in the present study, we proposed an individualized “treat to target” schedule by subgroups (Figure 1).

Conclusion: Five phenotypes of sarcoidosis with different clinical and prognostic characteristics are proposed in our study. Cluster analysis can be a useful tool for identifying clinical patterns in a disease as heterogeneous as sarcoidosis and facilitating its management.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/identification-of-clinical-phenotypes-in-sarcoidosis-using-a-cluster-analysis/