Full Papers
Serological clusters in inflammatory myositis and its clinical and prognostic implications: a longitudinal cohort study
S. Abdellaoui1, M. Gharnaout2, S. Nouioua3, S. Lefkir-Tafiani4
- Department of Rheumatology, Issad Hassani Beni Messous Hospital, Algiers, Algeria. sante76@hotmail.fr
- Department of Pneumology, Issad Hassani Beni Messous Hospital, Algiers, Algeria.
- Department of Neurology, EHS Cherchell Hospital, Algiers, Algeria.
- Department of Rheumatology, Issad Hassani Beni Messous Hospital, Algiers, Algeria.
CER24
Full Papers
Received: 28/01/2026
Accepted : 18/05/2026
In Press: 22/05/2026
Abstract
OBJECTIVES:
Clinicoserologic inflammatory myopathies (IM) classification has revolutionised the diagnostic approach to this heterogeneous disease entity. The objective of this study was to determine the subgroups predictive prognostic factors that formed after a population cluster analysis.
METHODS:
Prospective multicentre study of 108 subjects with myositis. An ascending hierarchical classification (AHC) was carried out on the axes of a multiple correspondence analysis (MCA) to group individuals into homogeneous clusters. Prognostic predictors were identified using binary logistic regression. “R” software was used in the statistical analysis.
RESULTS:
82 patients were women (75.9%), aged 50.4±14.7. Patients were split according to clinical and immunological data of those with: antisynthetase syndrome (ASS) 34 (38.6%), dermatomyositis (DM) 31 (28.7%), overlap myositis (OM) 27(30.7%), seronegative myositis 8 (7.4%), immune-mediated necrotising myositis (IMNM) 6 (6.8%) and inclusion body myositis (IBM) 2 (2.3%). MCA analysis differentiates three clusters: Cluster 1 (n=27) including OM patients characterised by dysphagia, creatine kinase (CK) level >225 with very few men. Cluster 2 (n=34) included ASS patients, mainly men (<50 years), smokers, with arthritis and cytoplasmic ANA. Cluster 3 (n=31) included DM patients aged ≥50 years having strength limitation (MMT8 ≤3) contrasting with low CK level with typical skin involvement. Second line IS use (OR=4.3; 95% CI 1.55–12.49) and cytoplasmic ANA (OR=4 .4; 95% CI 1.64–12.61) was ASS predictive; MMT8 ≤3 (OR=4.5; 95% CI 1.58–14.46) was DM predictive and dysphagia (OR=3.55; 95% CI 1.13–12.17), diagnostic delay (OR=3.41; 95% CI 1.17–10.32) were OM predictive.
CONCLUSIONS:
Antibodies in myositis has a double diagnostic and prognostic interest and each cluster is fairly well defined by specific prognosis predictive factors.
